CNS Vasculitis

Autoimmune MONDO:0015374 Pathograph 13 Show in embeddings browser Autoimmune Disorder Neurological Disease Vascular disorder

CNS vasculitis is a rare vasculitic disorder affecting vessels of the brain and spinal cord. This entry focuses on primary angiitis of the central nervous system, an idiopathic vasculitis restricted to the CNS after secondary infectious, systemic autoimmune, malignant, and drug-related causes are excluded.

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3
Definitions
5
Pathophys.
4
Histopath.
34
Phenotypes
2
Gaps
13
Pathograph
7
Medical Actions
5
Subtypes
3
Differentials
1
Datasets
3
Trials
56
References
2
Deep Research
📘

Definitions

3
Orphanet disease definition
Orphanet defines primary angiitis of the CNS as focal or diffuse neurologic symptoms from documented arteritis in CNS medium or small vessels, without another infectious, systemic, or neurologic cause.
CASE_DEFINITION
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"A rare, medium or small vessel vasculitis characterized by focal and/or diffuse neurologic symptoms due to a documented arteritic process in the central nervous system, in the absence of other identified underlying cause (infectious, systemic, other neurologic diseases, etc.)."
Orphanet provides the rare-disease definition and exclusion of secondary causes.
Calabrese-Mallek diagnostic criteria
Classic PACNS criteria require an unexplained neurologic deficit, CNS angiographic or tissue evidence of arteritis, and exclusion of systemic vasculitis or secondary mimics.
DIAGNOSTIC_CRITERIA
Classic PACNS criteria
Unexplained neurologic deficit plus angiographic or tissue evidence of CNS arteritis, with no systemic or secondary cause.
Minimum required: 3
Inclusion criteria
  • Acquired otherwise unexplained neurologic deficit
  • Angiographic or histopathological evidence of CNS angiitis
  • No systemic vasculitis or other cause of the findings
Show evidence (2 references)
PMID:3275856 SUPPORT DIRECT REVIEW SYNTHESIS Other
"This study proposes to establish diagnostic criteria for PACNS which would include 1) the presence of an unexplained neurologic deficit after thorough clinical and laboratory evaluation; 2) documentation by cerebral angiography and/or tissue examination of an arteritic process within the central..."
The abstract states the classic diagnostic criteria used to separate primary CNS vasculitis from mimics.
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"PACNS is a rare disease whose diagnostic criteria are commonly used but poorly validated with knock-on effects on how the diagnosis is reached and the therapeutic choices made in clinical practice."
The guideline distinguishes widespread use from established diagnostic validity.
Notes: These widely used criteria are historical and incompletely validated. Angiographic abnormalities alone are nonspecific; modern evaluation integrates clinical, CSF, vascular imaging and tissue findings with exclusion of mimics.
Birnbaum-Hellmann diagnostic certainty
The 2009 framework, used in the ESO guideline, separates histologically definite disease from probable disease supported by a high-probability angiogram, abnormal brain MRI and compatible CSF. These categories do not eliminate the need to exclude mimics.
DIAGNOSTIC_CRITERIA
Show evidence (1 reference)
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"A “definite” diagnosis of PACNS requires histopathological confirmation of vasculitis on cerebral biopsy or autopsy. A “probable” diagnosis requires a high-probability angiogram with abnormal findings on magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) profile consistent with PACNS."
The guideline explicitly states the different evidentiary requirements for definite and probable PACNS.
◆

Subtypes

5
Angiography-positive large/medium-vessel PCNSV
Angiographic ascertainment generally identifies large/medium-vessel disease. In the Mayo cohort this group had more hemiparesis, infarcts and mortality; angiographic abnormalities are nonspecific and require exclusion of mimics. Diagnostic modality and vessel size do not correspond perfectly.
Show evidence (2 references)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The patients diagnosed by angiograms more frequently had at presentation hemiparesis or a persistent neurologic deficit or stroke, more frequent infarcts on MRI and an increased mortality."
The cohort describes the angiography-positive subgroup and its clinical severity.
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Biopsy-proven PACNS underlines mainly the involvement of small vessels, substantially under the resolution of catheter angiography, but there is not a perfect correspondence, being theoretically possible a medium vessel involvement and a positive biopsy."
Diagnostic ascertainment is an imperfect proxy for the size of the affected vessels.
Biopsy-positive small-vessel PCNSV
Histologically confirmed disease is often small-vessel predominant and can coexist with angiographic abnormalities. The Mayo cohort found more cognitive dysfunction, CSF protein elevation and leptomeningeal enhancement in this group. Lower disability and mortality in that cohort should not be generalized to every biopsy-positive patient.
Show evidence (2 references)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The patients diagnosed by biopsy more frequently had at presentation cognitive dysfunction, greater cerebrospinal fluid total protein concentrations, less frequent cerebral infarcts, and more frequent leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging (MRI), along with less..."
The Mayo cohort distinguishes biopsy-diagnosed small-vessel disease from angiography-diagnosed disease.
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Biopsy-proven PACNS underlines mainly the involvement of small vessels, substantially under the resolution of catheter angiography, but there is not a perfect correspondence, being theoretically possible a medium vessel involvement and a positive biopsy."
Diagnostic ascertainment is an imperfect proxy for the size of the affected vessels.
Prominent leptomeningeal-enhancing PCNSV
An overlapping imaging phenotype, described in a small Mayo series, with prominent gadolinium meningeal enhancement, abnormal CSF, normal angiography in many cases, and prompt treatment response. It can coexist with amyloid-associated disease and does not define a mutually exclusive subtype.
Show evidence (1 reference)
PMID:18240248 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Prominent gadolinium leptomeningeal enhancement on MRI may point to a distinct subtype of PCNSV with small leptomeningeal artery vasculitis and rapid response to therapy."
This study defines a small-vessel leptomeningeal-enhancing subtype.
PCNSV with spinal cord involvement
Rare subset with spinal cord vasculitis, usually with concurrent cerebral involvement, thoracic or cervical cord abnormalities, and increased relapse risk.
Show evidence (2 references)
PMID:40110603 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Of 216 patients, 10 (4.6%) had spinal cord involvement, with cerebral involvement in 9 cases. One patient (0.5%) had isolated spinal cord vasculitis."
The updated Mayo cohort quantifies spinal cord involvement in PCNSV.
PMID:40110603 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Spinal cord involvement defines a distinct subset of patients with PCNSV."
The authors explicitly identify spinal involvement as a distinct subset.
?

Discussions and Knowledge Gaps

2
Does localized complement activation contribute to primary CNS vascular injury?
KNOWLEDGE GAP OPEN complement-activation
CSF proteomics in eight biopsy-confirmed cases found altered complement-protein abundance, but a subsequent 20-patient study found no increased CSF or serum complement activation products. Protein abundance and activation are different measurements. A local endothelial mechanism remains unresolved; these studies do not establish a complement-targeted treatment for PACNS.
Show evidence (3 references)
PMID:31270218 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Compared to noninflammatory controls, 283 proteins were differentially expressed in the CSF of patients with PACNS, with significant enrichment of the complement cascade pathway (C4-binding protein, CD55, CD59, properdin, complement C5, complement C8, and complement C9) and neural cell adhesion..."
Exploratory proteomics identified complement-associated protein changes.
PMID:34066885 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"While we did not find any evidence for enhanced complement activation in the CSF of patients with PACNS, our study has limitations which should be accounted for when interpreting the results."
The later study did not reproduce the proposed activation signal.
PMID:34066885 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Our study does not formally exclude that complement activation in PACNS occurs on the endothelium in situ without being detectable in the CSF."
The authors distinguish absence of a fluid activation signal from exclusion of localized vascular activation.
Do exploratory plasma metabolic signatures reliably identify PACNS or its activity?
KNOWLEDGE GAP OPEN metabolic-biomarker-validation
A 35-patient plasma metabolomics study reported energy, amino-acid and lipid pathway associations and reused five lymphocytic PACNS and four control brain transcriptomes from GSE213907. External validation is lacking. Metabolite abundance and pathway enrichment do not directly measure metabolic flux or establish a causal metabolic driver of vasculitis.
Show evidence (2 references)
PMID:40026305 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Additionally, external validation is lacking for the applicability of the biomarkers for clinical diagnosis."
The study explicitly identifies the translational validation gap.
PMID:40026305 SUPPORT DIRECT PRIMARY RESULT Computational
"In Cohort 2, we evaluated brain tissue transcriptomic information from five patients with PACNS and four control patients, and 844 differentially expressed genes were detected, with 741 upregulated and 103 and downregulated genes."
The transcriptomic comparison is small and reuses a subset of the existing dataset.
⚙

Pathophysiology

5
CNS Vessel Wall Inflammation
Mechanism confidence: Established
Inflammatory cells infiltrate CNS vessel walls. Adult biopsy specimens show transmural lymphocytic, granulomatous or necrotizing patterns. Pediatric small-vessel disease is predominantly lymphocytic; its histological criteria remain under validation.
T cell CL:0000084 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T cell (CL:0000084). CL:0000084 is a cell type from the Cell Ontology. macrophage CL:0000235 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves macrophage (CL:0000235). CL:0000235 is a cell type from the Cell Ontology. endothelial cell CL:0000115 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves endothelial cell (CL:0000115). CL:0000115 is a cell type from the Cell Ontology.
inflammatory response GO:0006954 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased inflammatory response (GO:0006954). GO:0006954 is a biological process from the Gene Ontology.
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology. spinal cord UBERON:0002240 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in spinal cord (UBERON:0002240). UBERON:0002240 is an anatomical location from the Uberon multi-species anatomy ontology. blood vessel UBERON:0001981 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in blood vessel (UBERON:0001981). UBERON:0001981 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Vascular Luminal Occlusion Mural inflammation can obliterate the vascular lumen.
Necrotizing Vessel Wall Injury A subset of inflammatory lesions develops fibrinoid vessel-wall necrosis.
Show evidence (2 references)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Transmural lymphoplasmacytic inflammation involving small-sized and medium-sized vessels, predominantly in the meninges, causing obliteration of the vascular lumen in some vessels"
Biopsy demonstrates mural inflammatory infiltration and luminal obliteration in small-vessel PCNSV.
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Most of the inflammatory cells are T lymphocytes as highlighted by immunohistochemical stain for CD3."
Immunohistochemistry identifies T lymphocytes in the illustrated inflammatory lesion.
Vascular Luminal Occlusion
Mechanism confidence: Established
Inflammatory vascular lesions can markedly narrow or obliterate the lumen. This process occurs in biopsy-demonstrated small vessels as well as angiographically visible arteries; diagnostic modality is not itself a mechanism.
blood vessel UBERON:0001981 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in blood vessel (UBERON:0001981). UBERON:0001981 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Cerebral Ischemic Injury Luminal occlusion compromises cerebral perfusion and can cause infarction.
Show evidence (1 reference)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Transmural lymphoplasmacytic inflammation involving small-sized and medium-sized vessels, predominantly in the meninges, causing obliteration of the vascular lumen in some vessels"
Biopsy demonstrates mural inflammatory infiltration and luminal obliteration in small-vessel PCNSV.
Cerebral Ischemic Injury
Mechanism confidence: Established
Compromised cerebral blood supply produces ischemic tissue injury and infarction. Focal deficits depend on lesion distribution; this node does not attribute every cognitive symptom or seizure to infarction.
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Stroke Cerebral infarction can manifest as ischemic stroke.
Show evidence (1 reference)
PMID:30860105 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and cognitive dysfunction in 5 (11.1%) patients."
This independent cohort documents common neurologic presentations.
Necrotizing Vessel Wall Injury
Mechanism confidence: Established
Destructive transmural inflammation with fibrinoid necrosis weakens affected vessel walls. This is a histological subset of PACNS rather than a universal lesion.
blood vessel UBERON:0001981 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in blood vessel (UBERON:0001981). UBERON:0001981 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Intracranial Hemorrhage Wall weakening can permit vessel rupture and intracranial bleeding.
Show evidence (1 reference)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The destructive transmural vasculitic process with fibrinoid necrosis may cause severe vessel wall weakening, thus predisposing to blood vessel ruptures."
The cohort discussion interprets the association of necrotizing histology and hemorrhage as vessel-wall fragility.
Immune Transcriptomic Signature
Mechanism confidence: Provisional
Bulk RNA sequencing of 13 PCNSV brain specimens and four controls identified immune-associated expression signatures. Pathway analysis inferred increased antigen processing, dendritic-cell maturation and neuroinflammation with reduced oxidative-phosphorylation signaling. CIBERSORT inferred enrichment of several immune-cell populations. These analyses do not establish cell counts, functional pathway activation, mitochondrial failure, or temporal causation of vessel-wall injury.
natural killer cell CL:0000623 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves natural killer cell (CL:0000623). CL:0000623 is a cell type from the Cell Ontology. M1 macrophage CL:0000863 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves M1 macrophage (CL:0000863). CL:0000863 is a cell type from the Cell Ontology. memory B cell CL:0000787 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves memory B cell (CL:0000787). CL:0000787 is a cell type from the Cell Ontology. T follicular helper cell CL:0002038 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves T follicular helper cell (CL:0002038). CL:0002038 is a cell type from the Cell Ontology.
antigen processing and presentation GO:0019882 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased antigen processing and presentation (GO:0019882). GO:0019882 is a biological process from the Gene Ontology. neuroinflammatory response GO:0150076 ↑ INCREASED Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased neuroinflammatory response (GO:0150076). GO:0150076 is a biological process from the Gene Ontology.
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology. blood vessel UBERON:0001981 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in blood vessel (UBERON:0001981). UBERON:0001981 is an anatomical location from the Uberon multi-species anatomy ontology.
Show evidence (3 references)
PMID:36264136 SUPPORT DIRECT PRIMARY RESULT Computational
"Pathway analysis revealed the activation of dendritic cell maturation and antigen processing as well as neuroinflammation in PCNSV versus normal brain, whereas oxidative phosphorylation was inhibited."
Pathway enrichment is an inference from patient tissue RNA expression, not a functional assay of antigen presentation or oxidative phosphorylation.
PMID:36264136 SUPPORT DIRECT PRIMARY RESULT Computational
"CIBERSORT estimation of immune cell subsets suggested that activated NK cells, M1 macrophages, memory B cells, and follicular helper T cells were likely to be more prevalent in PCNSV samples."
CIBERSORT estimates cell composition from bulk RNA-seq; the reported cell types were not directly enumerated by this analysis.
PMID:36264136 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Brain specimens of 4 patients with granulomatous vasculitis (GV), 5 with lymphocytic vasculitis (LV), 4 with amyloid β-related angiitis (ABRA), and 4 normal controls were studied."
The exploratory study includes 13 cases across three histological groups and four controls; it does not establish inherited genetic causation.
✶

Histopathology

4
Granulomatous vascular inflammation
Granulomatous vascular inflammation is a recognized biopsy pattern, especially in CAA-associated and leptomeningeal-enhancing PCNSV subsets.
Show evidence (1 reference)
PMID:18753193 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Histologically, all had a granulomatous vascular inflammatory pattern."
The CAA-associated subset showed granulomatous vascular inflammation on biopsy.
Necrotizing vasculitis
Necrotizing vasculitis can be seen in biopsy-confirmed PCNSV, particularly in spinal-cord involvement cohorts.
Show evidence (1 reference)
PMID:40110603 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Histological evidence of vasculitis was found in all 10, with necrotizing vasculitis in 5 (50%)."
This cohort documents necrotizing vasculitis in spinal-cord PCNSV biopsies.
Lymphocytic vasculitis
Lymphocytic mural inflammation is a recognized adult pattern and predominates in childhood small-vessel disease. Its association with a more favorable prognosis in Mayo analyses was not reproduced in the German multicenter cohort.
Show evidence (2 references)
PMID:32062032 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Lymphocytic vasculitis on biopsy was associated with a more benign course with reduced disability and mortality."
Long-term follow-up links lymphocytic vasculitis histology to outcomes.
PMID:40546217 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"In our study, we found no relevant impact of the lymphocytic pattern on outcome, but we did find that a necrotizing pattern was associated with a decrease in overall survival."
The German study limits generalization of the favorable-prognosis association.
Pediatric angiocentric lymphocytic inflammation
In childhood small-vessel PACNS, moderate-to-severe angiocentric lymphocytic infiltrates and reactive endothelium are characteristic candidate histological features. Granulomas, necrosis and fibrin deposits were absent in the 31-case study. Isolated leptomeningeal inflammation was not discriminatory; the proposed composite criteria require external validation.
Show evidence (2 references)
PMID:39732702 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"CD3, CD4, CD8, and CD20 cells predominated the inflammatory infiltrate. Reactive endothelium was strongly associated with sv-cPACNS, with an OR of 8.93 (p = 0.001). Features reported in adult sv-PACNS, including granulomas, necrosis, or fibrin deposits, were absent in all biopsies."
Blinded evaluation distinguishes pediatric histological findings from adult necrotizing and granulomatous patterns.
PMID:39732702 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Moderate to severe angiocentric inflammatory infiltrates in cortex or white matter consisting of CD3, CD4 or CD8 together with reactive endothelium showed sensitivity of 20% and specificity of 95% with negative predictive value of 0.4 and positive predictive value of 0.8."
The proposed composite has low sensitivity despite high specificity within this study; it is not a validated exclusion test.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for CNS Vasculitis Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

34
Blood 1
Intracranial Hemorrhage OCCASIONAL HP:0002170 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intracranial hemorrhage (HP:0002170). HP:0002170 is a phenotype from the Human Phenotype Ontology.
The Orphanet frequency band and clinical hemorrhagic-stroke presentations are distinct from susceptibility-weighted MRI microbleeds. A selected biopsy-confirmed imaging cohort reported very frequent micro/macrohemorrhages; this does not imply that nearly all PACNS patients have symptomatic hemorrhagic stroke. The paper gives discordant counts in its abstract (54/56) and results (53/55).
Show evidence (4 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002170 | Intracranial hemorrhage | Occasional (29-5%)"
Orphanet lists intracranial hemorrhage as occasional.
DOI:10.1038/s41598-024-55222-2 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Microhemorrhages and/or macrohemorrhages were detected in 53 out of 55 patients (96.4%)."
The full-text results quantify SWI findings in a selected biopsy-positive cohort; these include microbleeds and are not a clinical stroke frequency estimate.
PMID:30860105 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and cognitive dysfunction in 5 (11.1%) patients."
The cohort reports hemorrhagic stroke as an initial presentation.
+ 1 more reference
Cardiovascular 3
Cerebral Vasculitis VERY_FREQUENT HP:0005318 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cerebral vasculitis (HP:0005318). HP:0005318 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0005318 | Cerebral vasculitis | Very frequent (99-80%)"
Orphanet lists cerebral vasculitis as a very frequent phenotype.
Stroke FREQUENT HP:0001297 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Stroke (HP:0001297). HP:0001297 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001297 | Stroke | Frequent (79-30%)"
Orphanet lists stroke as frequent.
PMID:30860105 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and cognitive dysfunction in 5 (11.1%) patients."
This clinical cohort reports ischemic and hemorrhagic stroke as presenting events.
Transient Ischemic Attack FREQUENT HP:0002326 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Transient ischemic attack (HP:0002326). HP:0002326 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002326 | Transient ischemic attack | Frequent (79-30%)"
Orphanet lists transient ischemic attack as frequent.
Digestive 1
Nausea and Vomiting FREQUENT HP:0002017 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Nausea and vomiting (HP:0002017). HP:0002017 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002017 | Nausea and vomiting | Frequent (79-30%)"
Orphanet lists nausea and vomiting as frequent.
Ear 1
Vertigo VERY_RARE HP:0002321 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Vertigo (HP:0002321). HP:0002321 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002321 | Vertigo | Very rare (<4-1%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Eye 7
Visual Disturbance Abnormality of vision HP:0000504 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormality of vision (HP:0000504). HP:0000504 is a phenotype from the Human Phenotype Ontology.
Coarse binding: source unspecified
Show evidence (1 reference)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Headache and cognitive dysfunction were the most common symptoms at presentation, followed by hemiparesis, persistent neurologic deficit or stroke, and visual symptoms. Each of the above-mentioned symptoms was present in more than one-third of the 163 patients."
The results support visual symptoms and their cohort-specific frequency without specifying a single visual phenotype.
Pseudopapilledema VERY_RARE HP:0000538 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Pseudopapilledema (HP:0000538). HP:0000538 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0000538 | Pseudopapilledema | Very rare (<4-1%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Blurred vision OCCASIONAL HP:0000622 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Blurred vision (HP:0000622). HP:0000622 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0000622 | Blurred vision | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Diplopia OCCASIONAL HP:0000651 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Diplopia (HP:0000651). HP:0000651 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0000651 | Diplopia | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Reduced visual acuity OCCASIONAL HP:0007663 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Reduced visual acuity (HP:0007663). HP:0007663 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0007663 | Reduced visual acuity | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Abnormal visual field test OCCASIONAL HP:0030588 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal visual field test (HP:0030588). HP:0030588 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0030588 | Abnormal visual field test | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Amaurosis fugax VERY_RARE HP:0100576 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Amaurosis fugax (HP:0100576). HP:0100576 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0100576 | Amaurosis fugax | Very rare (<4-1%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Metabolism 2
Abnormal CSF Protein Concentration FREQUENT HP:0025456 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal CSF protein concentration (HP:0025456). HP:0025456 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0025456 | Abnormal CSF protein level | Frequent (79-30%)"
Orphanet lists abnormal CSF protein as frequent.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The patients diagnosed by biopsy more frequently had at presentation cognitive dysfunction, greater cerebrospinal fluid total protein concentrations, less frequent cerebral infarcts, and more frequent leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging (MRI), along with less..."
The biopsy-positive subgroup had increased CSF protein.
Fever OCCASIONAL HP:0001945 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Fever (HP:0001945). HP:0001945 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001945 | Fever | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Nervous System 18
Headache FREQUENT HP:0002315 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Headache (HP:0002315). HP:0002315 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002315 | Headache | Frequent (79-30%)"
Orphanet lists headache as frequent.
PMID:3275856 SUPPORT DIRECT REVIEW SYNTHESIS Other
"headache was the most common symptom (58%)"
The original diagnostic-criteria review found headache was the most common symptom.
Hemiparesis FREQUENT HP:0001269 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hemiparesis (HP:0001269). HP:0001269 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001269 | Hemiparesis | Frequent (79-30%)"
Orphanet lists hemiparesis as frequent.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The patients diagnosed by angiograms more frequently had at presentation hemiparesis or a persistent neurologic deficit or stroke, more frequent infarcts on MRI and an increased mortality."
The Mayo cohort links hemiparesis to the angiography-positive subgroup.
Paralysis FREQUENT HP:0003470 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Paralysis (HP:0003470). HP:0003470 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0003470 | Paralysis | Frequent (79-30%)"
Orphanet lists paralysis as frequent, distinct from hemiparesis.
Cognitive Impairment FREQUENT HP:0100543 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cognitive impairment (HP:0100543). HP:0100543 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0100543 | Cognitive impairment | Frequent (79-30%)"
Orphanet lists cognitive impairment as frequent.
PMID:30860105 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and cognitive dysfunction in 5 (11.1%) patients."
This clinical cohort reports cognitive dysfunction at onset.
Aphasia FREQUENT HP:0002381 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Aphasia (HP:0002381). HP:0002381 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002381 | Aphasia | Frequent (79-30%)"
Orphanet lists aphasia as frequent.
Multifocal Cerebral White Matter Abnormalities FREQUENT HP:0007052 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Multifocal cerebral white matter abnormalities (HP:0007052). HP:0007052 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0007052 | Multifocal cerebral white matter abnormalities | Frequent (79-30%)"
Orphanet lists multifocal cerebral white matter abnormalities as frequent.
Recurrent Subcortical Infarcts FREQUENT HP:0007236 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Recurrent subcortical infarcts (HP:0007236). HP:0007236 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0007236 | Recurrent subcortical infarcts | Frequent (79-30%)"
Orphanet lists recurrent subcortical infarcts as frequent.
CSF Pleocytosis FREQUENT HP:0012229 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is CSF pleocytosis (HP:0012229). HP:0012229 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0012229 | CSF pleocytosis | Frequent (79-30%)"
Orphanet lists CSF pleocytosis as frequent.
Seizure OCCASIONAL HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Frequency varies substantially by ascertainment and cohort. The Orphanet band summarizes the disease generally; selected biopsy-confirmed small-vessel series report higher seizure frequencies.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001250 | Seizure | Occasional (29-5%)"
Orphanet lists seizures as occasional.
PMID:30860105 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and cognitive dysfunction in 5 (11.1%) patients."
This cohort reports seizures as an initial presentation.
Ataxia OCCASIONAL HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001251 | Ataxia | Occasional (29-5%)"
Orphanet lists ataxia as occasional.
Paraparesis OCCASIONAL HP:0002385 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Paraparesis (HP:0002385). HP:0002385 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002385 | Paraparesis | Occasional (29-5%)"
Orphanet lists paraparesis as occasional.
PMID:40110603 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Compared with the 206 patients without spinal cord involvement, those with spinal cord vasculitis were more likely to present with paraparesis/tetraparesis (P<0.001) and necrotizing vasculitis (P=0.01) and less likely with hemiparesis (P=0.006) and granulomatous vasculitis (P=0.03)."
Spinal cord PCNSV is enriched for paraparesis or tetraparesis.
Intellectual Disability in Childhood Disease HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:30762375 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Intellectual disability (FSIQ < 70) was more frequent in children with small-vessel disease (24% vs. 5%)."
Age-specific cohort evidence supports intellectual disability after childhood disease.
Dysarthria OCCASIONAL HP:0001260 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001260 | Dysarthria | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Parkinsonism VERY_RARE HP:0001300 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Parkinsonism (HP:0001300). HP:0001300 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0001300 | Parkinsonism | Very rare (<4-1%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Tetraparesis OCCASIONAL HP:0002273 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Tetraparesis (HP:0002273). HP:0002273 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0002273 | Tetraparesis | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Transient global amnesia OCCASIONAL HP:0010534 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Transient global amnesia (HP:0010534). HP:0010534 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0010534 | Transient global amnesia | Occasional (29-5%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
Gait Disturbance HP:0001288 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Chronic neurologic symptoms were common, including cognitive dysfunction (92.3%), chronic motor deficits (73.1%), inability to ambulate without assistance (38.5%), migraines (23.1%), and epilepsy (11.5%)."
The follow-up results document persistent ambulatory disability in this selected small-vessel cohort.
Encephalopathy HP:0001298 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Encephalopathy (HP:0001298). HP:0001298 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The most common symptoms at the time of the first clinical presentation were headache (76.9%), altered mental status (61.5%), seizures (38.5%), and focal weakness (34.6%, eTable 2)."
Altered mental status represents the encephalopathic clinical presentation in this small-vessel series.
Constitutional 1
Constitutional symptom VERY_RARE HP:0025142 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constitutional symptom (HP:0025142). HP:0025142 is a phenotype from the Human Phenotype Ontology.
Coarse binding: source unspecified
Show evidence (1 reference)
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"HP:0025142 | Constitutional symptom | Very rare (<4-1%)"
Orphanet reports this phenotype and frequency band for primary CNS angiitis.
💊

Medical Actions

7
Glucocorticoid therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: corticosteroid CHEBI:50858 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses corticosteroid (CHEBI:50858). CHEBI:50858 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
High-dose glucocorticoids are central to induction therapy, either alone in selected cases or combined with additional immunosuppression for higher-risk disease.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (2 references)
PMID:25708615 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"A favorable response was observed in 85% of patients treated with prednisone alone and in 80% of patients treated with prednisone and cyclophosphamide."
This cohort supports glucocorticoid-based treatment responses.
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"The group’s recommendations on induction and maintenance of treatment and for primary or secondary prevention of vascular events also reflect uncertainty due to lack of evidence."
The ESO guideline supports cautious interpretation of treatment evidence.
Glucocorticoid and cyclophosphamide induction
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: corticosteroid CHEBI:50858 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses corticosteroid (CHEBI:50858). CHEBI:50858 is a therapeutic agent from Chemical Entities of Biological Interest. cyclophosphamide CHEBI:4027 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses cyclophosphamide (CHEBI:4027). CHEBI:4027 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Glucocorticoids with cyclophosphamide are commonly used for induction, particularly in severe disease. Observational Mayo and German cohorts associate cyclophosphamide-based regimens with fewer relapses. A biopsy-proven small-vessel series associated earlier cyclophosphamide with faster remission, without demonstrating a statistically significant functional benefit. Confounding by treatment selection limits causal comparisons.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (4 references)
PMID:3275856 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Therapy of PACNS with a combination of cytotoxic drugs and high-dose corticosteroids has greatly improved the prognosis for this condition."
The original criteria review supports cytotoxic-drug plus high-dose corticosteroid therapy.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Relapses occurred in one-quarter of the patients and were less frequent in patients treated with prednisone and cyclophosphamide compared with those treated with prednisone alone."
The large cohort supports reduced relapse with combined prednisone and cyclophosphamide.
PMID:40546217 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Patients treated with cyclophosphamide alone or in combination with steroids had a lower incidence of relapse than untreated patients"
The German cohort reports an association with fewer relapses versus untreated periods; nonrandomized treatment and confounding by indication prevent a causal efficacy conclusion.
+ 1 more reference
Mycophenolate mofetil steroid-sparing therapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: mycophenolate mofetil CHEBI:8764 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses mycophenolate mofetil (CHEBI:8764). CHEBI:8764 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Mycophenolate mofetil is an induction alternative or maintenance immunosuppressant in observational PCNSV series. Favorable disability associations in the Mayo cohort do not establish superiority to cyclophosphamide; comparative safety and relapse evidence remain limited.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (3 references)
PMID:25800827 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"MMF in combination with GCs achieved a favorable response in most patients."
This PCNSV treatment cohort supports MMF with glucocorticoids.
PMID:32062032 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Mycophenolate mofetil may be an effective alternative to CYC."
Long-term follow-up supports MMF as a possible alternative to cyclophosphamide.
PMID:25800827 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"No statistically significant differences were observed regarding relapses and ability to discontinue therapy at last follow-up."
The Mayo comparison did not establish a relapse advantage for mycophenolate.
Azathioprine maintenance immunosuppression
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: azathioprine CHEBI:2948 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses azathioprine (CHEBI:2948). CHEBI:2948 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Azathioprine is used as a steroid-sparing maintenance immunosuppressant in CNS vasculitis cohorts after induction therapy, though drug-specific comparative efficacy remains limited.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (1 reference)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"19 received maintenance immunosuppression with azathioprine (n = 9), mycophenolate mofetil (MMF, n = 7), prednisone (n = 2), or methotrexate (n = 1)."
The biopsy-proven small-vessel PACNS series documents maintenance use; it does not compare the efficacy of individual maintenance drugs.
Rituximab for selected refractory PCNSV
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: rituximab NCIT:C1702 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses rituximab (NCIT:C1702). NCIT:C1702 is a therapeutic agent from the NCI Thesaurus.
Platform: Monoclonal antibody
Rituximab is supported only by small observational series and literature review data, so it is best represented as a selected refractory or individualized therapy rather than standard first-line treatment.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (2 references)
PMID:30743080 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Five of the 6 were refractory to high dose glucocorticoids (GCs) and/or conventional immunosuppressants (IS)."
This supports rituximab use mainly in refractory PCNSV cases.
PMID:30743080 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Our data support a potential role for RTX treatment in selected patients with PCNSV."
The authors conclude rituximab may have a selected role.
Methotrexate maintenance immunosuppression
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: methotrexate CHEBI:44185 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses methotrexate (CHEBI:44185). CHEBI:44185 is a therapeutic agent from Chemical Entities of Biological Interest.
Platform: Small molecule
Methotrexate is one steroid-sparing maintenance option after induction. PACNS-specific comparative efficacy is uncertain; its use is supported by observational experience and expert synthesis.
Mechanism Target:
CNS Vessel Wall Inflammation
Show evidence (1 reference)
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"19 received maintenance immunosuppression with azathioprine (n = 9), mycophenolate mofetil (MMF, n = 7), prednisone (n = 2), or methotrexate (n = 1)."
Methotrexate was used for maintenance in one patient in this biopsy-confirmed small-vessel cohort; this documents use, not comparative efficacy.
Infliximab in selected refractory disease
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: Infliximab NCIT:C1789 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses Infliximab (NCIT:C1789). NCIT:C1789 is a therapeutic agent from the NCI Thesaurus.
Platform: Monoclonal antibody
Infliximab has anecdotal rescue-use evidence. A child with biopsy-confirmed progressive PACNS improved after infliximab following deterioration despite glucocorticoids, intravenous immunoglobulin, cyclophosphamide and rituximab. A single sequentially treated case cannot establish efficacy, routine indications or an HLA-defined responsive subtype.
Mechanism Target:
INHIBITS CNS Vessel Wall Inflammation — Intended suppression of vascular inflammation in refractory disease; vessel-wall target engagement was not measured in the cited case.
Show evidence (1 reference)
PMID:41283854 SUPPORT INDIRECT PRIMARY RESULT Human Clinical
"Despite intravenous immunoglobulin, intravenous cyclophosphamide, and rituximab, the patient became comatose, and the brain MRI worsened. Following infliximab, clinical symptoms and brain MRI improved."
Improvement after rescue infliximab is consistent with its intended anti-inflammatory role; this uncontrolled case does not demonstrate a vessel-wall mechanism or establish efficacy.
Show evidence (1 reference)
PMID:41283854 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Despite intravenous immunoglobulin, intravenous cyclophosphamide, and rituximab, the patient became comatose, and the brain MRI worsened. Following infliximab, clinical symptoms and brain MRI improved."
This case reports clinical and imaging improvement after rescue treatment, with substantial confounding from preceding therapies.
🔬

Biochemical Markers

2
Circulating endothelial cells (Increased in active disease)
Show evidence (2 references)
PMID:32296382 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Patients with an active PACNS showed significantly higher CEC levels (480 CEC/ml, 304–1552) than PACNS patients in remission (54 CEC/ml, 4–100; p < 0.001, Figure 2) and also compared to healthy subjects (40 CEC/ml, 8–52; p < 0.001)."
The study measured increased CEC counts during active disease.
PMID:32296382 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"In patients with RCVS/MMD, CECs were also significantly elevated (288 CEC/ml, 184–352) compared to healthy controls (p < 0.001), but they were still significantly lower when compared to patients with an active PACNS (p = 0.017)."
Elevation also occurs in noninflammatory vasculopathies, limiting disease specificity.
IL-17 production by cultured CSF CD4 T cells (Increased after expansion and stimulation)
Show evidence (2 references)
PMID:27144213 SUPPORT DIRECT PRIMARY RESULT In Vitro
"Interestingly, all samples with CSF cells analyzed of patients with PACNS and SACNS groups showed high levels of IL-17-producing CD4+ cells (average 8.8%, range 7.3%–10.5%, for PACNS; average 10.4%, range 8.9%–11.9%, for SACNS)."
The primary-disease subgroup signal was measured in cultured CSF-derived cells.
PMID:27144213 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"We also assessed soluble IL-17 in the CSF of our patients using the highly sensitive MSD platform. All values were under detection levels, except for one patient where CSF was taken shortly before he died of a fulminant vasculitis"
Direct CSF cytokine measurement does not support generalized soluble IL-17 elevation.
🔬

Diagnosis

6
Cerebral angiography
Digital subtraction angiography assesses medium/large-vessel stenosis, dilation and occlusion. These findings support probable PACNS in the appropriate clinical setting but are not specific: RCVS and atherosclerosis can mimic them. Normal angiography does not exclude small-vessel disease.
angiography NCIT:C190556 NCI Thesaurus (NCIT)
Show evidence (3 references)
PMID:26020379 SUPPORT DIRECT BACKGROUND Other
"However, the accuracy of angiography remains uncertain because changes typical of vasculitis can also be seen in nonvasculitic disorders."
The cohort introduction explicitly cautions against treating an angiographic pattern as proof of inflammatory disease.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"A total of 105 patients were diagnosed by angiographic findings and 58 by biopsy results."
The Mayo cohort documents angiography-based diagnosis in most patients.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Angiograms were normal in 16 other patients who had positive brain biopsies suggesting in those that the involved vessels were too small to be visualized."
A normal angiogram did not exclude biopsy-confirmed small-vessel disease.
CNS biopsy
Brain or leptomeningeal biopsy can establish transmural vascular inflammation and identify mimics, especially in suspected small-vessel disease. Sampling error can produce a nondiagnostic result; targeting an abnormal region and including leptomeninges may improve yield. The decision requires individualized assessment of procedural risk and diagnostic value.
Show evidence (2 references)
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"In studies analyzing the precise site of the biopsy, the yield increased when the sample included leptomeninges, and/or when the biopsy was performed on a lesioned area."
The guideline synthesis supports lesion-directed sampling that includes leptomeninges.
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Six patients (23.1%) underwent repeat brain biopsy because of initial nondiagnostic findings."
Repeat sampling was needed in this selected biopsy-proven small-vessel cohort; an initially nondiagnostic biopsy is not an exclusion test.
Brain and spinal MRI
MRI helps identify infarcts, leptomeningeal enhancement, white-matter abnormalities, and spinal cord involvement, and helps stratify PCNSV subsets.
magnetic resonance imaging procedure NCIT:C16809 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The patients diagnosed by biopsy more frequently had at presentation cognitive dysfunction, greater cerebrospinal fluid total protein concentrations, less frequent cerebral infarcts, and more frequent leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging (MRI), along with less..."
MRI findings help distinguish PCNSV diagnostic subsets.
PMID:40110603 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Magnetic resonance imaging showed thoracic abnormalities in 8 patients, cervical spine involvement in 2, conus medullaris involvement in 3, and cauda equina enhancement in 4."
MRI identifies spinal cord involvement patterns.
Cerebrospinal fluid analysis
CSF cell count and protein can support the evaluation of inflammatory CNS disease but are nonspecific and can be normal in PACNS. CSF testing also helps identify infectious, malignant and other mimics; neither mild protein elevation nor pleocytosis establishes PACNS.
cerebrospinal fluid analysis NCIT:C173272 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:3275856 SUPPORT DIRECT REVIEW SYNTHESIS Other
"The diagnostic approach to PACNS should include a variety of laboratory tests and examination of the cerebral spinal fluid primarily to rule out mimicking conditions."
The diagnostic-criteria paper supports CSF examination as part of the diagnostic workup.
PMID:40334177 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Notably, 4 patients (17.4%) had a normal CSF profile on pretreatment testing, including a normal IgG index and no OCBs."
Normal pretreatment CSF occurred in a minority of this biopsy-proven small-vessel cohort.
Serum and CSF neurofilament light chain
Serum and CSF NfL are candidate markers of neuroaxonal injury. A small cross-sectional study associated higher levels with active PACNS, but age and recent ischemic stroke affect levels, and NfL is not specific for vasculitic inflammation. Longitudinal monitoring and diagnostic thresholds remain unvalidated.
Markers: Neurofilament light chain
Show evidence (3 references)
PMID:40643487 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Serum NfL was significantly elevated in aPACNS (median: 45.77 pg/mL) versus rPACNS (6.68 pg/mL; p < 0.001) and healthy controls (6.05 pg/mL; p < 0.001)."
The case-control study supports serum NfL elevation in active PACNS.
PMID:40643487 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"CONCLUSIONS: NfL holds potential as a biomarker for PACNS, in particular in younger patients."
The authors interpret NfL as a potential PACNS biomarker with age-dependent utility.
PMID:40643487 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Our study’s primary limitations include the small sample size, particularly for patients in remission, and the lack of multiple time points for NfL measurements."
Cross-sectional results cannot establish longitudinal monitoring performance.
High-resolution vessel wall MRI
Vessel wall MRI can show intense, concentric vessel-wall enhancement and can complement parenchymal MRI, MRA, DSA, and biopsy-oriented evaluation, but it is not a stand-alone diagnostic test.
magnetic resonance imaging procedure NCIT:C16809 NCI Thesaurus (NCIT)
Show evidence (2 references)
PMID:38732340 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"In HR-VW-MRI images, after the administration of the contrast agent, all six patients (100.0%) presented intense enhancement. In five patients (83.3%) the enhancement was concentric, and in one patient (16.7%) it was eccentric"
These results are restricted to the six primary cases in a mixed cohort of 14; none had histopathological confirmation.
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"Although the development of HRVWI-MRI is promising, it is not validated and has not been formally compared to other diagnostic techniques in patients with PACNS."
The guideline treats vessel-wall MRI as an adjunct with uncertain diagnostic accuracy, rather than a stand-alone test.
🩻

Imaging Findings

2
Vasogenic cerebral edema
MRI may show vasogenic edema surrounding inflammatory lesions, sometimes with local mass effect. This finding is nonspecific and does not establish vasculitis.
Mri
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON)
Show evidence (1 reference)
DOI:10.3389/fneur.2024.1363985 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Three patients demonstrated unilateral involvement with T2 hyperintensity and vasogenic edema surrounding the lesions, resulting in a local mass effect on fissures, gyrus, and ventricles"
The five-patient primary CNS vasculitis series documents edema and local mass effect on MRI.
Pseudotumoral inflammatory brain lesions
A minority of PACNS cases present with mass-like inflammatory lesions that can mimic neoplasm. The ESO synthesis reported a pseudotumoral pattern in 27 of 660 patients, while noting probable underreporting.
Mri
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON)
Show evidence (1 reference)
PMID:37903069 SUPPORT DIRECT REVIEW SYNTHESIS Other
"A pseudotumoral pattern was reported in a minority of patients (27/660 or 4.1%). This pattern was also likely to be underreported, but, in single institution case series, it was rare."
The guideline describes an uncommon tumor-like imaging presentation rather than a neoplastic diagnosis.
📈

Progression

3
Relapsing course
Relapse estimates differ by cohort, case definition and follow-up: approximately one-quarter to one-third in the overlapping Mayo cohorts and 50% in the independent German cohort. The German median observation time was 42 months. Associations between immunosuppressive regimens and fewer relapses are observational.
Show evidence (3 references)
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Relapses occurred in one-quarter of the patients and were less frequent in patients treated with prednisone and cyclophosphamide compared with those treated with prednisone alone."
The cohort links PCNSV to relapses and treatment-dependent relapse risk.
PMID:32062032 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"One or more relapses were observed in 30% of patients, 35% had discontinued therapy by last follow-up, and 21.5% maintained remission for at least 12 months after discontinuing therapy."
Long-term follow-up quantifies relapse, discontinuation, and sustained remission.
PMID:40546217 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Median time under observation for all patients was 42 months (range: 1–263) and median time to relapse in those with a relapse was 18 months (IQR: 4–55 months). Relapses occurred in 82 (50%) of all patients"
The independent German cohort had longer follow-up and a higher observed relapse proportion than the original Mayo series.
Poor-outcome risk
Mayo analyses associated infarcts, large-vessel involvement, angiographic diagnosis and older age with poorer outcomes. The German cohort instead found similar survival and relapse-free survival between ascertainment groups, and associated older age, diagnostic delay and necrotizing histology with mortality. Prognostic associations are cohort-dependent.
Show evidence (3 references)
PMID:25708615 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"diagnosis by angiography (HR 3.28), cerebral infarction (HR 4.44), and large vessel involvement (HR 4.98), while reduced mortality was associated with gadolinium-enhanced cerebral lesions or meninges (HR 0.20)."
This analysis identifies adverse prognostic factors in adult PCNSV.
PMID:40546217 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Poorer survival was associated with patient age (hazard ratio [HR], 1.96 [95% confidence interval (CI), 1.41-2.74] per 10 years), longer time between initial manifestation and diagnosis (HR, 1.01 [95% CI, 1.00-1.01] per month), and necrotizing subtype (HR, 10.2 [95% CI, 2.18-48.2])."
The complete result supports all three prognostic associations; the wide confidence interval limits precision for necrotizing histology.
PMID:40546217 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Overall survival and relapse‐free survival time did not differ significantly between biopsy‐confirmed and angiogram‐confirmed patients"
The German cohort does not reproduce a simple survival ranking by diagnostic modality.
Long-term functional and cognitive burden
Persistent disability can remain after treatment. The long-term questionnaire study had substantial nonresponse, limiting generalization. Anxiety and depression were distinct measured outcomes; most respondents had minimal or no depression. Childhood small-vessel disease was associated with poorer intellectual outcomes than large-vessel disease in a separate pediatric cohort.
Show evidence (3 references)
PMID:30789149 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Seventy-eight patients met the inclusion criteria, of which 27 responded to the questionnaire (34.6%). Mean follow-up of those who responded was 5.5 years (± 4.7). Nineteen of 27 patients (70.4%) had mild disability; meanwhile, 5 (18.5%) had severe disability."
Long-term disability was measured in 27 questionnaire respondents, not the entire 78-patient cohort.
PMID:30789149 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Approximately 70% of patients had minimal or no depression."
Most questionnaire respondents had minimal or no depression.
PMID:30762375 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Children with small-vessel CNS vasculitis had significantly lower FSIQ scores than did those with large-vessel CNS vasculitis (Ms = 81.90 vs. 94.82; p = .04). Intellectual disability (FSIQ < 70) was more frequent in children with small-vessel disease (24% vs. 5%)."
The pediatric cohort identifies a vessel-size-associated cognitive burden; these estimates should not be generalized to adults.
🌍

Epidemiology

1
Annual incidence estimate in Olmsted County, Minnesota
The Mayo studies estimated annual PCNSV incidence at 2.4 cases per 1,000,000 person-years in Olmsted County, Minnesota, age- and sex-weighted to the US white population. This local estimate is not a nationwide incidence survey. Orphanet separately reports a US annual incidence band of 1-9 per 1,000,000.
Show evidence (3 references)
PMID:17924545 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The annual incidence rate of PCNSV was 2.4 cases per 1,000,000 person-years."
The Mayo cohort provides an incidence estimate for PCNSV.
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"1-9 / 1 000 000 | United States | Annual incidence | PMID:21601163,PMID:21180634,PMID:22575778"
Orphanet reports a rare annual incidence band for the United States.
PMID:26020379 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"The estimated incidence rate of PCNSV in Olmsted County, Minnesota, was calculated using the estimates of country population. The rate reported herein was weighted by age and sex to reflect an underlying population that was demographically comparable with the US white population."
The methods specify the local population denominator and age/sex weighting; the incidence should not be represented as a national measurement.
🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from CNS Vasculitis:

Secondary CNS vasculitis and mimics
Overlapping Features Infectious, systemic autoimmune, malignant, drug-related, and other neurologic causes can mimic primary CNS vasculitis and must be excluded before assigning the primary diagnosis.
Distinguishing Features
  • Evidence of systemic vasculitis or another secondary cause argues against primary CNS vasculitis.
  • CSF, imaging, laboratory testing, angiography, and biopsy are used together to separate PACNS from mimics.
Show evidence (3 references)
PMID:3275856 SUPPORT DIRECT REVIEW SYNTHESIS Other
"no evidence of a systemic vasculitide or any other condition to which the angiographic or pathologic features could be secondary."
Exclusion of systemic or secondary causes is part of the classic PACNS criteria.
ORPHA:140989 SUPPORT DIRECT REVIEW SYNTHESIS Other
"in the absence of other identified underlying cause (infectious, systemic, other neurologic diseases, etc.)."
Orphanet likewise defines PACNS by excluding secondary causes.
DOI:10.1177/19418744231223283 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Compared to primary CNS vasculitis, secondary CNS vasculitis exhibits higher fever incidence (observed in infectious and connective tissue disorder [CTD]-associated vasculitis), low glucose levels (mostly in infectious vasculitis) and unique cerebrospinal fluid oligoclonal bands (observed in..."
This cohort gives specific features that favor secondary CNS vasculitis over primary disease.
Reversible cerebral vasoconstriction syndrome
Overlapping Features RCVS can resemble angiographic PACNS. Thunderclap headache and a compatible reversible vasoconstrictive course favor RCVS; an angiographic string-of-beads pattern alone does not distinguish the two.
Distinguishing Features
  • Thunderclap headache is a useful RCVS clue in the appropriate clinical context.
  • Angiographic beading can occur without inflammatory vasculitis.
Show evidence (1 reference)
PMID:22467936 SUPPORT DIRECT PRIMARY RESULT Human Clinical
"Thirteen patients had RCVS. Thunderclap headaches, the absence of a focal neurological deficit, a convexal subarachnoid hemorrhage and/or normal brain parenchyma on magnetic resonance imaging, and "string of beads" appearance on conventional angiography had high diagnostic value."
In this referred cohort, these features favored RCVS; they are not absolute diagnostic requirements or exclusion rules.
📊

Related Datasets

1
EXPLORING GENE EXPRESSION PROFILES IN PRIMARY CENTRAL NERVOUS SYSTEM VASCULITIS geo:GSE213907
Bulk RNA sequencing of brain specimens from primary CNS vasculitis and controls, associated with Salvarani et al. (PMID:36264136).
human BULK RNA SEQ n=17
The 17 specimens comprise four granulomatous vasculitis cases, five lymphocytic vasculitis cases, four amyloid-beta-related angiitis cases, and four controls. Pathway and immune-cell deconvolution analyses are exploratory; the dataset is not a functional perturbation experiment.
🔬

Clinical Trials

3
NCT03166319 NOT_APPLICABLE COMPLETED
Prospective pilot study of MRI and high-resolution intracranial vessel wall imaging for diagnosis and disease-activity assessment in suspected CNS vasculitis.
Show evidence (1 reference)
clinicaltrials:NCT03166319 SUPPORT DIRECT PRIMARY RESULT Other
"This is a prospective pilot study to determine the utility of MRI and high resolution intracranial vessel wall imaging for the diagnosis and disease activity assessment of intracranial vasculitis."
The trial directly studies vessel-wall imaging in suspected CNS vasculitis.
NCT05168475 PHASE_II TERMINATED
Phase 2 randomized trial of biologic therapy in refractory primary non-ANCA-associated vasculitis, a broader population than PACNS. The registry reports termination because NIHR withdrew funding. Registration and pooled trial results do not establish PACNS-specific efficacy.
Show evidence (1 reference)
clinicaltrials:NCT05168475 SUPPORT DIRECT PRIMARY RESULT Other
"The trial will include patients with Non-ANCA-associated vasculitis (NAAV)"
The trial is relevant to refractory non-ANCA vasculitis but is not specific to primary CNS vasculitis.
NCT00659776 PHASE_II TERMINATED
Phase 2 exploratory ferumoxytol MRI study for a broad range of CNS inflammatory and vascular lesions, including vasculitis. The registry reports termination because of staffing shortages and lack of funding during COVID. This is a diagnostic imaging study, not a PACNS treatment efficacy trial.
Show evidence (1 reference)
clinicaltrials:NCT00659776 SUPPORT DIRECT PRIMARY RESULT Other
"The protocol enrolls subjects with radiological or histological diagnosis of unknown, dural, or parenchymal CNS lesions, multiple sclerosis, TIA or stroke, vasculitis, or other vascular lesions"
The imaging study includes vasculitis among broader CNS inflammatory and vascular indications.
{ }

Source YAML

click to show 
name: CNS Vasculitis
creation_date: "2026-05-16T10:22:29Z"
description: >-
  CNS vasculitis is a rare vasculitic disorder affecting vessels of the brain
  and spinal cord. This entry focuses on primary angiitis of the central
  nervous system, an idiopathic vasculitis restricted to the CNS after secondary
  infectious, systemic autoimmune, malignant, and drug-related causes are
  excluded.
category: Autoimmune
disease_term:
  preferred_term: CNS vasculitis
  term:
    id: MONDO:0015374
    label: primary central nervous system vasculitis
parents:
- Autoimmune Disorder
- Neurological Disease
- Vascular disorder
synonyms:
- Primary angiitis of the central nervous system
- Primary central nervous system vasculitis
- Primary CNS vasculitis
- Isolated angiitis of the central nervous system
- Primary vasculitis of the central nervous system
- PACNS
- PCNSV
has_subtypes:
- name: Angiography-positive
  display_name: Angiography-positive large/medium-vessel PCNSV
  description: >-
    Angiographic ascertainment generally identifies large/medium-vessel disease. In the Mayo cohort this group had more hemiparesis, infarcts and mortality; angiographic abnormalities are nonspecific and require exclusion of mimics. Diagnostic modality and vessel size do not correspond perfectly.
  evidence:
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients diagnosed by angiograms more frequently had at presentation
      hemiparesis or a persistent neurologic deficit or stroke, more frequent
      infarcts on MRI and an increased mortality.
    explanation: The cohort describes the angiography-positive subgroup and its clinical severity.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      Biopsy-proven PACNS underlines mainly the involvement of small vessels, substantially under the resolution of catheter angiography, but there is not a perfect correspondence, being theoretically possible a medium vessel involvement and a positive biopsy.
    explanation: Diagnostic ascertainment is an imperfect proxy for the size of the affected vessels.
- name: Biopsy-positive
  display_name: Biopsy-positive small-vessel PCNSV
  description: >-
    Histologically confirmed disease is often small-vessel predominant and can coexist with angiographic abnormalities. The Mayo cohort found more cognitive dysfunction, CSF protein elevation and leptomeningeal enhancement in this group. Lower disability and mortality in that cohort should not be generalized to every biopsy-positive patient.
  evidence:
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients diagnosed by biopsy more frequently had at presentation
      cognitive dysfunction, greater cerebrospinal fluid total protein
      concentrations, less frequent cerebral infarcts, and more frequent
      leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging
      (MRI), along with less mortality and disability at last follow-up.
    explanation: The Mayo cohort distinguishes biopsy-diagnosed small-vessel disease from angiography-diagnosed disease.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      Biopsy-proven PACNS underlines mainly the involvement of small vessels, substantially under the resolution of catheter angiography, but there is not a perfect correspondence, being theoretically possible a medium vessel involvement and a positive biopsy.
    explanation: Diagnostic ascertainment is an imperfect proxy for the size of the affected vessels.
- name: CAA-related
  display_name: Cerebral amyloid angiopathy-related PCNSV
  description: >-
    Amyloid-beta-related angiitis (ABRA) combines vascular amyloid-beta deposition with true transmural vasculitis. It often has granulomatous inflammation, but lymphocytic ABRA also occurs. Perivascular nondestructive CAA-related inflammation is a differential diagnosis rather than equivalent evidence of vasculitis.
  evidence:
  - reference: PMID:18753193
    reference_title: "Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Eight cases (26%) with CNS biopsy specimens positive for PCNSV also showed
      findings of CAA.
    explanation: This biopsy cohort identifies CAA-associated PCNSV as a recurrent subset.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:18753193
    reference_title: "Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "PCNSV with CAA appears to form a clinical subset of PCNSV."
    explanation: The authors explicitly interpret PCNSV with CAA as a clinical subset.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Among both non-ABRA patients (n = 19) and those with ABRA (n = 7), the most common neuropathologic subtype of CNS vasculitis was lymphocytic (68.4% and 57.1%, respectively, Figure 2), followed by granulomatous (21.1% and 42.9%, respectively).
    explanation: ABRA was not invariably granulomatous in this biopsy-confirmed cohort.
- name: Leptomeningeal-enhancing
  display_name: Prominent leptomeningeal-enhancing PCNSV
  description: >-
    An overlapping imaging phenotype, described in a small Mayo series, with prominent gadolinium meningeal enhancement, abnormal CSF, normal angiography in many cases, and prompt treatment response. It can coexist with amyloid-associated disease and does not define a mutually exclusive subtype.
  evidence:
  - reference: PMID:18240248
    reference_title: "Primary central nervous system vasculitis with prominent leptomeningeal enhancement: a subset with a benign outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Prominent gadolinium leptomeningeal enhancement on MRI may point to a
      distinct subtype of PCNSV with small leptomeningeal artery vasculitis and
      rapid response to therapy.
    explanation: This study defines a small-vessel leptomeningeal-enhancing subtype.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Spinal cord involvement
  display_name: PCNSV with spinal cord involvement
  description: >-
    Rare subset with spinal cord vasculitis, usually with concurrent cerebral
    involvement, thoracic or cervical cord abnormalities, and increased relapse
    risk.
  evidence:
  - reference: PMID:40110603
    reference_title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Of 216 patients, 10 (4.6%) had spinal cord involvement, with cerebral
      involvement in 9 cases. One patient (0.5%) had isolated spinal cord
      vasculitis.
    explanation: The updated Mayo cohort quantifies spinal cord involvement in PCNSV.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40110603
    reference_title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Spinal cord involvement defines a distinct subset of patients with PCNSV."
    explanation: The authors explicitly identify spinal involvement as a distinct subset.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
definitions:
- name: Orphanet disease definition
  definition_type: CASE_DEFINITION
  description: >-
    Orphanet defines primary angiitis of the CNS as focal or diffuse neurologic
    symptoms from documented arteritis in CNS medium or small vessels, without
    another infectious, systemic, or neurologic cause.
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: >-
      A rare, medium or small vessel vasculitis characterized by focal and/or
      diffuse neurologic symptoms due to a documented arteritic process in the
      central nervous system, in the absence of other identified underlying
      cause (infectious, systemic, other neurologic diseases, etc.).
    explanation: Orphanet provides the rare-disease definition and exclusion of secondary causes.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Calabrese-Mallek diagnostic criteria
  definition_type: DIAGNOSTIC_CRITERIA
  description: >-
    Classic PACNS criteria require an unexplained neurologic deficit, CNS
    angiographic or tissue evidence of arteritis, and exclusion of systemic
    vasculitis or secondary mimics.
  criteria_sets:
  - name: Classic PACNS criteria
    description: >-
      Unexplained neurologic deficit plus angiographic or tissue evidence of CNS
      arteritis, with no systemic or secondary cause.
    minimum_required: 3
    inclusion_criteria:
    - preferred_term: Acquired otherwise unexplained neurologic deficit
    - preferred_term: Angiographic or histopathological evidence of CNS angiitis
    - preferred_term: No systemic vasculitis or other cause of the findings
  evidence:
  - reference: PMID:3275856
    reference_title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      This study proposes to establish diagnostic criteria for PACNS which would
      include 1) the presence of an unexplained neurologic deficit after thorough
      clinical and laboratory evaluation; 2) documentation by cerebral
      angiography and/or tissue examination of an arteritic process within the
      central nervous system; and 3) no evidence of a systemic vasculitide or
      any other condition to which the angiographic or pathologic features could
      be secondary.
    explanation: The abstract states the classic diagnostic criteria used to separate primary CNS vasculitis from mimics.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      PACNS is a rare disease whose diagnostic criteria are commonly used but poorly validated with knock-on effects on how the diagnosis is reached and the therapeutic choices made in clinical practice.
    explanation: The guideline distinguishes widespread use from established diagnostic validity.
  notes: >-
    These widely used criteria are historical and incompletely validated. Angiographic abnormalities alone are nonspecific; modern evaluation integrates clinical, CSF, vascular imaging and tissue findings with exclusion of mimics.
- name: Birnbaum-Hellmann diagnostic certainty
  definition_type: DIAGNOSTIC_CRITERIA
  description: >-
    The 2009 framework, used in the ESO guideline, separates histologically definite disease from probable disease supported by a high-probability angiogram, abnormal brain MRI and compatible CSF. These categories do not eliminate the need to exclude mimics.
  evidence:
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      A “definite” diagnosis of PACNS requires histopathological confirmation of vasculitis on cerebral biopsy or autopsy. A “probable” diagnosis requires a high-probability angiogram with abnormal findings on magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) profile consistent with PACNS.
    explanation: The guideline explicitly states the different evidentiary requirements for definite and probable PACNS.
epidemiology:
- name: Annual incidence estimate in Olmsted County, Minnesota
  unit: cases per 1,000,000 person-years
  notes: >-
    The Mayo studies estimated annual PCNSV incidence at 2.4 cases per 1,000,000 person-years in Olmsted County, Minnesota, age- and sex-weighted to the US white population. This local estimate is not a nationwide incidence survey. Orphanet separately reports a US annual incidence band of 1-9 per 1,000,000.
  evidence:
  - reference: PMID:17924545
    reference_title: "Primary central nervous system vasculitis: analysis of 101 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The annual incidence rate of PCNSV was 2.4 cases per 1,000,000 person-years."
    explanation: The Mayo cohort provides an incidence estimate for PCNSV.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "1-9 / 1 000 000 | United States | Annual incidence | PMID:21601163,PMID:21180634,PMID:22575778"
    explanation: Orphanet reports a rare annual incidence band for the United States.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      The estimated incidence rate of PCNSV in Olmsted County, Minnesota, was calculated using the estimates of country population. The rate reported herein was weighted by age and sex to reflect an underlying population that was demographically comparable with the US white population.
    explanation: The methods specify the local population denominator and age/sex weighting; the incidence should not be represented as a national measurement.
progression:
- phase: Relapsing course
  notes: >-
    Relapse estimates differ by cohort, case definition and follow-up: approximately one-quarter to one-third in the overlapping Mayo cohorts and 50% in the independent German cohort. The German median observation time was 42 months. Associations between immunosuppressive regimens and fewer relapses are observational.
  evidence:
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Relapses occurred in one-quarter of the patients and were less frequent in
      patients treated with prednisone and cyclophosphamide compared with those
      treated with prednisone alone.
    explanation: The cohort links PCNSV to relapses and treatment-dependent relapse risk.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:32062032
    reference_title: "Long-term remission, relapses and maintenance therapy in adult primary central nervous system vasculitis: A single-center 35-year experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      One or more relapses were observed in 30% of patients, 35% had
      discontinued therapy by last follow-up, and 21.5% maintained remission for
      at least 12 months after discontinuing therapy.
    explanation: Long-term follow-up quantifies relapse, discontinuation, and sustained remission.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40546217
    reference_title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Median time under observation for all patients was 42 months (range: 1–263) and median time to relapse in those with a relapse was 18 months (IQR: 4–55 months). Relapses occurred in 82 (50%) of all patients
    explanation: The independent German cohort had longer follow-up and a higher observed relapse proportion than the original Mayo series.
- phase: Poor-outcome risk
  notes: >-
    Mayo analyses associated infarcts, large-vessel involvement, angiographic diagnosis and older age with poorer outcomes. The German cohort instead found similar survival and relapse-free survival between ascertainment groups, and associated older age, diagnostic delay and necrotizing histology with mortality. Prognostic associations are cohort-dependent.
  evidence:
  - reference: PMID:25708615
    reference_title: "Adult primary central nervous system vasculitis treatment and course: analysis of one hundred sixty-three patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      diagnosis by angiography (HR 3.28), cerebral infarction (HR 4.44), and
      large vessel involvement (HR 4.98), while reduced mortality was associated
      with gadolinium-enhanced cerebral lesions or meninges (HR 0.20).
    explanation: This analysis identifies adverse prognostic factors in adult PCNSV.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40546217
    reference_title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Poorer survival was associated with patient age (hazard ratio [HR], 1.96 [95% confidence interval (CI), 1.41-2.74] per 10 years), longer time between initial manifestation and diagnosis (HR, 1.01 [95% CI, 1.00-1.01] per month), and necrotizing subtype (HR, 10.2 [95% CI, 2.18-48.2]).
    explanation: The complete result supports all three prognostic associations; the wide confidence interval limits precision for necrotizing histology.
  - reference: PMID:40546217
    reference_title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Overall survival and relapse‐free survival time did not differ significantly between biopsy‐confirmed and angiogram‐confirmed patients
    explanation: The German cohort does not reproduce a simple survival ranking by diagnostic modality.
- phase: Long-term functional and cognitive burden
  notes: >-
    Persistent disability can remain after treatment. The long-term questionnaire study had substantial nonresponse, limiting generalization. Anxiety and depression were distinct measured outcomes; most respondents had minimal or no depression. Childhood small-vessel disease was associated with poorer intellectual outcomes than large-vessel disease in a separate pediatric cohort.
  evidence:
  - reference: PMID:30789149
    reference_title: Long-term outcomes of patients with primary angiitis of the central nervous system.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Seventy-eight patients met the inclusion criteria, of which 27 responded to the questionnaire (34.6%). Mean follow-up of those who responded was 5.5 years (± 4.7). Nineteen of 27 patients (70.4%) had mild disability; meanwhile, 5 (18.5%) had severe disability.
    explanation: Long-term disability was measured in 27 questionnaire respondents, not the entire 78-patient cohort.
  - reference: PMID:30789149
    reference_title: Long-term outcomes of patients with primary angiitis of the central nervous system.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Approximately 70% of patients had minimal or no depression.
    explanation: Most questionnaire respondents had minimal or no depression.
  - reference: PMID:30762375
    reference_title: Cognitive outcomes of childhood primary CNS vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Children with small-vessel CNS vasculitis had significantly lower FSIQ scores than did those with large-vessel CNS vasculitis (Ms = 81.90 vs. 94.82; p = .04). Intellectual disability (FSIQ < 70) was more frequent in children with small-vessel disease (24% vs. 5%).
    explanation: The pediatric cohort identifies a vessel-size-associated cognitive burden; these estimates should not be generalized to adults.
pathophysiology:
- name: CNS Vessel Wall Inflammation
  description: >-
    Inflammatory cells infiltrate CNS vessel walls. Adult biopsy specimens show transmural lymphocytic, granulomatous or necrotizing patterns. Pediatric small-vessel disease is predominantly lymphocytic; its histological criteria remain under validation.
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  - preferred_term: spinal cord
    term:
      id: UBERON:0002240
      label: spinal cord
  - preferred_term: blood vessel
    term:
      id: UBERON:0001981
      label: blood vessel
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  biological_processes:
  - preferred_term: inflammatory response
    modifier: INCREASED
    term:
      id: GO:0006954
      label: inflammatory response
  downstream:
  - target: Vascular Luminal Occlusion
    description: Mural inflammation can obliterate the vascular lumen.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:40334177
      reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: >-
        Transmural lymphoplasmacytic inflammation involving small-sized and medium-sized vessels, predominantly in the meninges, causing obliteration of the vascular lumen in some vessels
      explanation: Biopsy demonstrates mural inflammatory infiltration and luminal obliteration in small-vessel PCNSV.
  - target: Necrotizing Vessel Wall Injury
    description: A subset of inflammatory lesions develops fibrinoid vessel-wall necrosis.
    causal_link_type: DIRECT
    evidence:
    - reference: PMID:40334177
      reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: >-
        Transmural lymphoplasmacytic inflammation associated with endothelial cell swelling and patchy areas of fibrinoid necrosis
      explanation: Histology demonstrates the necrotizing form of inflammatory wall injury; it is not present in every case.
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Transmural lymphoplasmacytic inflammation involving small-sized and medium-sized vessels, predominantly in the meninges, causing obliteration of the vascular lumen in some vessels
    explanation: Biopsy demonstrates mural inflammatory infiltration and luminal obliteration in small-vessel PCNSV.
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Most of the inflammatory cells are T lymphocytes as highlighted by immunohistochemical stain for CD3.
    explanation: Immunohistochemistry identifies T lymphocytes in the illustrated inflammatory lesion.
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
- name: Vascular Luminal Occlusion
  description: >-
    Inflammatory vascular lesions can markedly narrow or obliterate the lumen. This process occurs in biopsy-demonstrated small vessels as well as angiographically visible arteries; diagnostic modality is not itself a mechanism.
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  locations:
  - preferred_term: blood vessel
    term:
      id: UBERON:0001981
      label: blood vessel
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Transmural lymphoplasmacytic inflammation involving small-sized and medium-sized vessels, predominantly in the meninges, causing obliteration of the vascular lumen in some vessels
    explanation: Biopsy demonstrates mural inflammatory infiltration and luminal obliteration in small-vessel PCNSV.
  downstream:
  - target: Cerebral Ischemic Injury
    causal_link_type: DIRECT
    description: Luminal occlusion compromises cerebral perfusion and can cause infarction.
    evidence:
    - reference: PMID:41947889
      reference_title: 'Overview of Primary Angiitis of the Central Nervous System: Current Insights.'
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
      snippet: >-
        As the disease progresses, vascular inflammation may lead to vessel occlusion or rupture, with subsequent ischemic or hemorrhagic infarctions
      explanation: The review explicitly connects vascular injury to downstream ischemic and hemorrhagic injury.
- name: Cerebral Ischemic Injury
  description: >-
    Compromised cerebral blood supply produces ischemic tissue injury and infarction. Focal deficits depend on lesion distribution; this node does not attribute every cognitive symptom or seizure to infarction.
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:30860105
    reference_title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic
      stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and
      cognitive dysfunction in 5 (11.1%) patients.
    explanation: This independent cohort documents common neurologic presentations.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  downstream:
  - target: Stroke
    causal_link_type: DIRECT
    description: Cerebral infarction can manifest as ischemic stroke.
    evidence:
    - reference: PMID:41947889
      reference_title: 'Overview of Primary Angiitis of the Central Nervous System: Current Insights.'
      supports: SUPPORT
      evidence_source: OTHER
      quote_role: REVIEW_SYNTHESIS
      directness: DIRECT
      snippet: >-
        As the disease progresses, vascular inflammation may lead to vessel occlusion or rupture, with subsequent ischemic or hemorrhagic infarctions
      explanation: The review explicitly connects vascular injury to downstream ischemic and hemorrhagic injury.
- name: Necrotizing Vessel Wall Injury
  description: >-
    Destructive transmural inflammation with fibrinoid necrosis weakens affected vessel walls. This is a histological subset of PACNS rather than a universal lesion.
  biological_scale: TISSUE
  mechanism_confidence: ESTABLISHED
  locations:
  - preferred_term: blood vessel
    term:
      id: UBERON:0001981
      label: blood vessel
  evidence:
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      The destructive transmural vasculitic process with fibrinoid necrosis may cause severe vessel wall weakening, thus predisposing to blood vessel ruptures.
    explanation: The cohort discussion interprets the association of necrotizing histology and hemorrhage as vessel-wall fragility.
  downstream:
  - target: Intracranial Hemorrhage
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    intermediate_mechanisms:
    - Vessel rupture
    description: Wall weakening can permit vessel rupture and intracranial bleeding.
    evidence:
    - reference: PMID:26020379
      reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: DIRECT
      snippet: >-
        The destructive transmural vasculitic process with fibrinoid necrosis may cause severe vessel wall weakening, thus predisposing to blood vessel ruptures.
      explanation: The cohort discussion interprets the association of necrotizing histology and hemorrhage as vessel-wall fragility.
- name: Immune Transcriptomic Signature
  description: >-
    Bulk RNA sequencing of 13 PCNSV brain specimens and four controls identified immune-associated expression signatures. Pathway analysis inferred increased antigen processing, dendritic-cell maturation and neuroinflammation with reduced oxidative-phosphorylation signaling. CIBERSORT inferred enrichment of several immune-cell populations. These analyses do not establish cell counts, functional pathway activation, mitochondrial failure, or temporal causation of vessel-wall injury.
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  - preferred_term: blood vessel
    term:
      id: UBERON:0001981
      label: blood vessel
  cell_types:
  - preferred_term: natural killer cell
    term:
      id: CL:0000623
      label: natural killer cell
    description: Population inferred by CIBERSORT from bulk tissue RNA expression; not directly counted.
  - preferred_term: M1 macrophage
    term:
      id: CL:0000863
      label: M1 macrophage
    description: Population inferred by CIBERSORT from bulk tissue RNA expression; not directly counted.
  - preferred_term: memory B cell
    term:
      id: CL:0000787
      label: memory B cell
    description: Population inferred by CIBERSORT from bulk tissue RNA expression; not directly counted.
  - preferred_term: T follicular helper cell
    term:
      id: CL:0002038
      label: T follicular helper cell
    description: Population inferred by CIBERSORT from bulk tissue RNA expression; not directly counted.
  biological_processes:
  - preferred_term: antigen processing and presentation
    modifier: INCREASED
    term:
      id: GO:0019882
      label: antigen processing and presentation
    description: Increased pathway signature inferred from bulk RNA sequencing, without a functional activity assay.
  - preferred_term: neuroinflammatory response
    modifier: INCREASED
    term:
      id: GO:0150076
      label: neuroinflammatory response
    description: Increased pathway signature inferred from bulk RNA sequencing, without a functional activity assay.
  evidence:
  - reference: PMID:36264136
    reference_title: Exploring Gene Expression Profiles in Primary Central Nervous System Vasculitis.
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: >-
      Pathway analysis revealed the activation of dendritic cell maturation and
      antigen processing as well as neuroinflammation in PCNSV versus normal
      brain, whereas oxidative phosphorylation was inhibited.
    explanation: Pathway enrichment is an inference from patient tissue RNA expression, not a functional assay of antigen presentation or oxidative phosphorylation.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:36264136
    reference_title: Exploring Gene Expression Profiles in Primary Central Nervous System Vasculitis.
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    snippet: >-
      CIBERSORT estimation of immune cell subsets suggested that activated NK
      cells, M1 macrophages, memory B cells, and follicular helper T cells were
      likely to be more prevalent in PCNSV samples.
    explanation: CIBERSORT estimates cell composition from bulk RNA-seq; the reported cell types were not directly enumerated by this analysis.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:36264136
    reference_title: Exploring Gene Expression Profiles in Primary Central Nervous System Vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Brain specimens of 4 patients with granulomatous vasculitis (GV), 5 with lymphocytic vasculitis (LV), 4 with amyloid β-related angiitis (ABRA), and 4 normal controls were studied.
    explanation: The exploratory study includes 13 cases across three histological groups and four controls; it does not establish inherited genetic causation.
  biological_scale: MOLECULAR
  mechanism_confidence: PROVISIONAL
histopathology:
- name: Granulomatous vascular inflammation
  description: >-
    Granulomatous vascular inflammation is a recognized biopsy pattern,
    especially in CAA-associated and leptomeningeal-enhancing PCNSV subsets.
  diagnostic: true
  evidence:
  - reference: PMID:18753193
    reference_title: "Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Histologically, all had a granulomatous vascular inflammatory pattern."
    explanation: The CAA-associated subset showed granulomatous vascular inflammation on biopsy.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Necrotizing vasculitis
  description: >-
    Necrotizing vasculitis can be seen in biopsy-confirmed PCNSV, particularly
    in spinal-cord involvement cohorts.
  diagnostic: true
  evidence:
  - reference: PMID:40110603
    reference_title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Histological evidence of vasculitis was found in all 10, with necrotizing
      vasculitis in 5 (50%).
    explanation: This cohort documents necrotizing vasculitis in spinal-cord PCNSV biopsies.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Lymphocytic vasculitis
  description: >-
    Lymphocytic mural inflammation is a recognized adult pattern and predominates in childhood small-vessel disease. Its association with a more favorable prognosis in Mayo analyses was not reproduced in the German multicenter cohort.
  diagnostic: true
  evidence:
  - reference: PMID:32062032
    reference_title: "Long-term remission, relapses and maintenance therapy in adult primary central nervous system vasculitis: A single-center 35-year experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Lymphocytic vasculitis on biopsy was associated with a more benign course
      with reduced disability and mortality.
    explanation: Long-term follow-up links lymphocytic vasculitis histology to outcomes.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40546217
    reference_title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      In our study, we found no relevant impact of the lymphocytic pattern on outcome, but we did find that a necrotizing pattern was associated with a decrease in overall survival.
    explanation: The German study limits generalization of the favorable-prognosis association.
- name: Pediatric angiocentric lymphocytic inflammation
  description: >-
    In childhood small-vessel PACNS, moderate-to-severe angiocentric lymphocytic infiltrates and reactive endothelium are characteristic candidate histological features. Granulomas, necrosis and fibrin deposits were absent in the 31-case study. Isolated leptomeningeal inflammation was not discriminatory; the proposed composite criteria require external validation.
  context: Childhood small-vessel PACNS
  evidence:
  - reference: PMID:39732702
    reference_title: Towards a histological diagnosis of childhood small vessel CNS vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      CD3, CD4, CD8, and CD20 cells predominated the inflammatory infiltrate. Reactive endothelium was strongly associated with sv-cPACNS, with an OR of 8.93 (p = 0.001). Features reported in adult sv-PACNS, including granulomas, necrosis, or fibrin deposits, were absent in all biopsies.
    explanation: Blinded evaluation distinguishes pediatric histological findings from adult necrotizing and granulomatous patterns.
  - reference: PMID:39732702
    reference_title: Towards a histological diagnosis of childhood small vessel CNS vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Moderate to severe angiocentric inflammatory infiltrates in cortex or white matter consisting of CD3, CD4 or CD8 together with reactive endothelium showed sensitivity of 20% and specificity of 95% with negative predictive value of 0.4 and positive predictive value of 0.8.
    explanation: The proposed composite has low sensitivity despite high specificity within this study; it is not a validated exclusion test.
phenotypes:
- name: Cerebral Vasculitis
  category: Vascular
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Cerebral vasculitis
    term:
      id: HP:0005318
      label: Cerebral vasculitis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0005318 | Cerebral vasculitis | Very frequent (99-80%)"
    explanation: Orphanet lists cerebral vasculitis as a very frequent phenotype.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Headache
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Headache
    term:
      id: HP:0002315
      label: Headache
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002315 | Headache | Frequent (79-30%)"
    explanation: Orphanet lists headache as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:3275856
    reference_title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "headache was the most common symptom (58%)"
    explanation: The original diagnostic-criteria review found headache was the most common symptom.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Stroke
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Stroke
    term:
      id: HP:0001297
      label: Stroke
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0001297 | Stroke | Frequent (79-30%)"
    explanation: Orphanet lists stroke as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:30860105
    reference_title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic
      stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and
      cognitive dysfunction in 5 (11.1%) patients.
    explanation: This clinical cohort reports ischemic and hemorrhagic stroke as presenting events.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Transient Ischemic Attack
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Transient ischemic attack
    term:
      id: HP:0002326
      label: Transient ischemic attack
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002326 | Transient ischemic attack | Frequent (79-30%)"
    explanation: Orphanet lists transient ischemic attack as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Hemiparesis
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hemiparesis
    term:
      id: HP:0001269
      label: Hemiparesis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0001269 | Hemiparesis | Frequent (79-30%)"
    explanation: Orphanet lists hemiparesis as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients diagnosed by angiograms more frequently had at presentation
      hemiparesis or a persistent neurologic deficit or stroke, more frequent
      infarcts on MRI and an increased mortality.
    explanation: The Mayo cohort links hemiparesis to the angiography-positive subgroup.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Nausea and Vomiting
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Nausea and vomiting
    term:
      id: HP:0002017
      label: Nausea and vomiting
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002017 | Nausea and vomiting | Frequent (79-30%)"
    explanation: Orphanet lists nausea and vomiting as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Paralysis
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Paralysis
    term:
      id: HP:0003470
      label: Paralysis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0003470 | Paralysis | Frequent (79-30%)"
    explanation: Orphanet lists paralysis as frequent, distinct from hemiparesis.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Cognitive Impairment
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0100543 | Cognitive impairment | Frequent (79-30%)"
    explanation: Orphanet lists cognitive impairment as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:30860105
    reference_title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic
      stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and
      cognitive dysfunction in 5 (11.1%) patients.
    explanation: This clinical cohort reports cognitive dysfunction at onset.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Aphasia
  category: Neurologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Aphasia
    term:
      id: HP:0002381
      label: Aphasia
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002381 | Aphasia | Frequent (79-30%)"
    explanation: Orphanet lists aphasia as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Multifocal Cerebral White Matter Abnormalities
  category: Radiologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Multifocal cerebral white matter abnormalities
    term:
      id: HP:0007052
      label: Multifocal cerebral white matter abnormalities
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0007052 | Multifocal cerebral white matter abnormalities | Frequent (79-30%)"
    explanation: Orphanet lists multifocal cerebral white matter abnormalities as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Recurrent Subcortical Infarcts
  category: Radiologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Recurrent subcortical infarcts
    term:
      id: HP:0007236
      label: Recurrent subcortical infarcts
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0007236 | Recurrent subcortical infarcts | Frequent (79-30%)"
    explanation: Orphanet lists recurrent subcortical infarcts as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: CSF Pleocytosis
  category: Laboratory
  frequency: FREQUENT
  phenotype_term:
    preferred_term: CSF pleocytosis
    term:
      id: HP:0012229
      label: CSF pleocytosis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0012229 | CSF pleocytosis | Frequent (79-30%)"
    explanation: Orphanet lists CSF pleocytosis as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Abnormal CSF Protein Concentration
  category: Laboratory
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Abnormal CSF protein concentration
    term:
      id: HP:0025456
      label: Abnormal CSF protein concentration
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0025456 | Abnormal CSF protein level | Frequent (79-30%)"
    explanation: Orphanet lists abnormal CSF protein as frequent.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients diagnosed by biopsy more frequently had at presentation
      cognitive dysfunction, greater cerebrospinal fluid total protein
      concentrations, less frequent cerebral infarcts, and more frequent
      leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging
      (MRI), along with less mortality and disability at last follow-up.
    explanation: The biopsy-positive subgroup had increased CSF protein.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Seizure
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0001250 | Seizure | Occasional (29-5%)"
    explanation: Orphanet lists seizures as occasional.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:30860105
    reference_title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic
      stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and
      cognitive dysfunction in 5 (11.1%) patients.
    explanation: This cohort reports seizures as an initial presentation.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  notes: Frequency varies substantially by ascertainment and cohort. The Orphanet band summarizes the disease generally; selected biopsy-confirmed small-vessel series report higher seizure frequencies.
- name: Ataxia
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0001251 | Ataxia | Occasional (29-5%)"
    explanation: Orphanet lists ataxia as occasional.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
- name: Paraparesis
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Paraparesis
    term:
      id: HP:0002385
      label: Paraparesis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002385 | Paraparesis | Occasional (29-5%)"
    explanation: Orphanet lists paraparesis as occasional.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:40110603
    reference_title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Compared with the 206 patients without spinal cord involvement, those with
      spinal cord vasculitis were more likely to present with
      paraparesis/tetraparesis (P<0.001) and necrotizing vasculitis (P=0.01)
      and less likely with hemiparesis (P=0.006) and granulomatous vasculitis
      (P=0.03).
    explanation: Spinal cord PCNSV is enriched for paraparesis or tetraparesis.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Intracranial Hemorrhage
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Intracranial hemorrhage
    term:
      id: HP:0002170
      label: Intracranial hemorrhage
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: "HP:0002170 | Intracranial hemorrhage | Occasional (29-5%)"
    explanation: Orphanet lists intracranial hemorrhage as occasional.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: DOI:10.1038/s41598-024-55222-2
    reference_title: 'The role of susceptibility-weighted imaging &amp; contrast-enhanced MRI in the diagnosis of primary CNS vasculitis: a large case series'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Microhemorrhages and/or macrohemorrhages were detected in 53 out of 55 patients (96.4%).
    explanation: The full-text results quantify SWI findings in a selected biopsy-positive cohort; these include microbleeds and are not a clinical stroke frequency estimate.
  - reference: PMID:30860105
    reference_title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The initial presentation was ischemic stroke in 15 (33.3%), hemorrhagic
      stroke in 4 (8.9%), headache in 11 (24.4%), seizures in 8 (17.8%) and
      cognitive dysfunction in 5 (11.1%) patients.
    explanation: The cohort reports hemorrhagic stroke as an initial presentation.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: DOI:10.1038/s41598-024-55222-2
    reference_title: 'The role of susceptibility-weighted imaging &amp; contrast-enhanced MRI in the diagnosis of primary CNS vasculitis: a large case series'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    directness: DIRECT
    snippet: >-
      patients with hemorrhages might have been more likely to undergo DSA or brain biopsy in our setting; other etiologies were considered when there were no microhemorrhages.
    explanation: The authors explicitly acknowledge ascertainment bias toward hemorrhagic imaging findings.
  notes: >-
    The Orphanet frequency band and clinical hemorrhagic-stroke presentations are distinct from susceptibility-weighted MRI microbleeds. A selected biopsy-confirmed imaging cohort reported very frequent micro/macrohemorrhages; this does not imply that nearly all PACNS patients have symptomatic hemorrhagic stroke. The paper gives discordant counts in its abstract (54/56) and results (53/55).
- name: Visual Disturbance
  category: Ophthalmologic
  phenotype_term:
    preferred_term: Abnormality of vision
    term:
      id: HP:0000504
      label: Abnormality of vision
    coarse_binding_basis: SOURCE_UNSPECIFIED
  description: >-
    Visual symptoms occurred in more than one-third of the Mayo 163-patient cohort. The aggregate category does not specify the type of visual impairment.
  evidence:
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Headache and cognitive dysfunction were the most common symptoms at presentation, followed by hemiparesis, persistent neurologic deficit or stroke, and visual symptoms. Each of the above-mentioned symptoms was present in more than one-third of the 163 patients.
    explanation: The results support visual symptoms and their cohort-specific frequency without specifying a single visual phenotype.
- name: Intellectual Disability in Childhood Disease
  category: Neurologic
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  description: >-
    Intellectual disability was reported after childhood-onset CNS vasculitis, particularly in the small-vessel group. In an 80-child cognitive-outcome cohort, the proportions were 24% for small-vessel and 5% for large-vessel disease; these are not adult prevalence estimates.
  context: Childhood-onset CNS vasculitis
  evidence:
  - reference: PMID:30762375
    reference_title: Cognitive outcomes of childhood primary CNS vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Intellectual disability (FSIQ < 70) was more frequent in children with small-vessel disease (24% vs. 5%).
    explanation: Age-specific cohort evidence supports intellectual disability after childhood disease.
- name: Pseudopapilledema
  category: Ophthalmologic
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Pseudopapilledema
    term:
      id: HP:0000538
      label: Pseudopapilledema
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0000538 | Pseudopapilledema | Very rare (<4-1%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Blurred vision
  category: Ophthalmologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Blurred vision
    term:
      id: HP:0000622
      label: Blurred vision
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0000622 | Blurred vision | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Diplopia
  category: Ophthalmologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Diplopia
    term:
      id: HP:0000651
      label: Diplopia
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0000651 | Diplopia | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Dysarthria
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0001260 | Dysarthria | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Parkinsonism
  category: Neurologic
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Parkinsonism
    term:
      id: HP:0001300
      label: Parkinsonism
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0001300 | Parkinsonism | Very rare (<4-1%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Fever
  category: Constitutional
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0001945 | Fever | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Tetraparesis
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Tetraparesis
    term:
      id: HP:0002273
      label: Tetraparesis
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0002273 | Tetraparesis | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Vertigo
  category: Neurologic
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Vertigo
    term:
      id: HP:0002321
      label: Vertigo
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0002321 | Vertigo | Very rare (<4-1%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Reduced visual acuity
  category: Ophthalmologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Reduced visual acuity
    term:
      id: HP:0007663
      label: Reduced visual acuity
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0007663 | Reduced visual acuity | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Transient global amnesia
  category: Neurologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Transient global amnesia
    term:
      id: HP:0010534
      label: Transient global amnesia
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0010534 | Transient global amnesia | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Constitutional symptom
  category: Constitutional
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Constitutional symptom
    term:
      id: HP:0025142
      label: Constitutional symptom
    coarse_binding_basis: SOURCE_UNSPECIFIED
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0025142 | Constitutional symptom | Very rare (<4-1%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Abnormal visual field test
  category: Ophthalmologic
  frequency: OCCASIONAL
  phenotype_term:
    preferred_term: Abnormal visual field test
    term:
      id: HP:0030588
      label: Abnormal visual field test
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0030588 | Abnormal visual field test | Occasional (29-5%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Amaurosis fugax
  category: Ophthalmologic
  frequency: VERY_RARE
  phenotype_term:
    preferred_term: Amaurosis fugax
    term:
      id: HP:0100576
      label: Amaurosis fugax
  evidence:
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      HP:0100576 | Amaurosis fugax | Very rare (<4-1%)
    explanation: Orphanet reports this phenotype and frequency band for primary CNS angiitis.
- name: Gait Disturbance
  category: Neurologic
  phenotype_term:
    preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  description: >-
    Persistent ambulatory disability occurs in small-vessel PACNS; 38.5% of a 26-patient biopsy-confirmed cohort could not walk without assistance.
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Chronic neurologic symptoms were common, including cognitive dysfunction (92.3%), chronic motor deficits (73.1%), inability to ambulate without assistance (38.5%), migraines (23.1%), and epilepsy (11.5%).
    explanation: The follow-up results document persistent ambulatory disability in this selected small-vessel cohort.
- name: Encephalopathy
  category: Neurologic
  phenotype_term:
    preferred_term: Encephalopathy
    term:
      id: HP:0001298
      label: Encephalopathy
  description: >-
    Diffuse cerebral dysfunction can present with altered mental status. In the UCSF biopsy-confirmed small-vessel cohort, altered mental status was a presenting symptom in 61.5%.
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      The most common symptoms at the time of the first clinical presentation were headache (76.9%), altered mental status (61.5%), seizures (38.5%), and focal weakness (34.6%, eTable 2).
    explanation: Altered mental status represents the encephalopathic clinical presentation in this small-vessel series.
diagnosis:
- name: Cerebral angiography
  description: >-
    Digital subtraction angiography assesses medium/large-vessel stenosis, dilation and occlusion. These findings support probable PACNS in the appropriate clinical setting but are not specific: RCVS and atherosclerosis can mimic them. Normal angiography does not exclude small-vessel disease.
  diagnosis_term:
    preferred_term: angiography
    term:
      id: NCIT:C190556
      label: Angiography
  evidence:
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: BACKGROUND
    directness: DIRECT
    snippet: >-
      However, the accuracy of angiography remains uncertain because changes typical of vasculitis can also be seen in nonvasculitic disorders.
    explanation: The cohort introduction explicitly cautions against treating an angiographic pattern as proof of inflammatory disease.
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 105 patients were diagnosed by angiographic findings and 58 by biopsy results."
    explanation: The Mayo cohort documents angiography-based diagnosis in most patients.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Angiograms were normal in 16 other patients who had positive brain biopsies suggesting in those that the involved vessels were too small to be visualized.
    explanation: A normal angiogram did not exclude biopsy-confirmed small-vessel disease.
- name: CNS biopsy
  description: >-
    Brain or leptomeningeal biopsy can establish transmural vascular inflammation and identify mimics, especially in suspected small-vessel disease. Sampling error can produce a nondiagnostic result; targeting an abnormal region and including leptomeninges may improve yield. The decision requires individualized assessment of procedural risk and diagnostic value.
  evidence:
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      In studies analyzing the precise site of the biopsy, the yield increased when the sample included leptomeninges, and/or when the biopsy was performed on a lesioned area.
    explanation: The guideline synthesis supports lesion-directed sampling that includes leptomeninges.
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Six patients (23.1%) underwent repeat brain biopsy because of initial nondiagnostic findings.
    explanation: Repeat sampling was needed in this selected biopsy-proven small-vessel cohort; an initially nondiagnostic biopsy is not an exclusion test.
- name: Brain and spinal MRI
  description: >-
    MRI helps identify infarcts, leptomeningeal enhancement, white-matter
    abnormalities, and spinal cord involvement, and helps stratify PCNSV
    subsets.
  diagnosis_term:
    preferred_term: magnetic resonance imaging procedure
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  evidence:
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The patients diagnosed by biopsy more frequently had at presentation
      cognitive dysfunction, greater cerebrospinal fluid total protein
      concentrations, less frequent cerebral infarcts, and more frequent
      leptomeningeal gadolinium-enhanced lesions on magnetic resonance imaging
      (MRI), along with less mortality and disability at last follow-up.
    explanation: MRI findings help distinguish PCNSV diagnostic subsets.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40110603
    reference_title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Magnetic resonance imaging showed thoracic abnormalities in 8 patients,
      cervical spine involvement in 2, conus medullaris involvement in 3, and
      cauda equina enhancement in 4.
    explanation: MRI identifies spinal cord involvement patterns.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Cerebrospinal fluid analysis
  description: >-
    CSF cell count and protein can support the evaluation of inflammatory CNS disease but are nonspecific and can be normal in PACNS. CSF testing also helps identify infectious, malignant and other mimics; neither mild protein elevation nor pleocytosis establishes PACNS.
  diagnosis_term:
    preferred_term: cerebrospinal fluid analysis
    term:
      id: NCIT:C173272
      label: CSF Analysis
  evidence:
  - reference: PMID:3275856
    reference_title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnostic approach to PACNS should include a variety of laboratory
      tests and examination of the cerebral spinal fluid primarily to rule out
      mimicking conditions.
    explanation: The diagnostic-criteria paper supports CSF examination as part of the diagnostic workup.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Notably, 4 patients (17.4%) had a normal CSF profile on pretreatment testing, including a normal IgG index and no OCBs.
    explanation: Normal pretreatment CSF occurred in a minority of this biopsy-proven small-vessel cohort.
- name: Serum and CSF neurofilament light chain
  description: >-
    Serum and CSF NfL are candidate markers of neuroaxonal injury. A small cross-sectional study associated higher levels with active PACNS, but age and recent ischemic stroke affect levels, and NfL is not specific for vasculitic inflammation. Longitudinal monitoring and diagnostic thresholds remain unvalidated.
  markers: Neurofilament light chain
  evidence:
  - reference: PMID:40643487
    reference_title: Neurofilament Light Chain in Serum and CSF as a Potential Biomarker for Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Serum NfL was significantly elevated in aPACNS (median: 45.77 pg/mL)
      versus rPACNS (6.68 pg/mL; p < 0.001) and healthy controls (6.05 pg/mL; p
      < 0.001).
    explanation: The case-control study supports serum NfL elevation in active PACNS.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40643487
    reference_title: Neurofilament Light Chain in Serum and CSF as a Potential Biomarker for Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      CONCLUSIONS: NfL holds potential as a biomarker for PACNS, in particular
      in younger patients.
    explanation: The authors interpret NfL as a potential PACNS biomarker with age-dependent utility.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40643487
    reference_title: Neurofilament Light Chain in Serum and CSF as a Potential Biomarker for Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Our study’s primary limitations include the small sample size, particularly for patients in remission, and the lack of multiple time points for NfL measurements.
    explanation: Cross-sectional results cannot establish longitudinal monitoring performance.
- name: High-resolution vessel wall MRI
  description: >-
    Vessel wall MRI can show intense, concentric vessel-wall enhancement and
    can complement parenchymal MRI, MRA, DSA, and biopsy-oriented evaluation,
    but it is not a stand-alone diagnostic test.
  diagnosis_term:
    preferred_term: magnetic resonance imaging procedure
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  evidence:
  - reference: PMID:38732340
    reference_title: The Contribution of Vessel Wall Magnetic Resonance Imaging to the Diagnosis of Primary and Secondary Central Nervous System Vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      In HR-VW-MRI images, after the administration of the contrast agent, all six patients (100.0%) presented intense enhancement. In five patients (83.3%) the enhancement was concentric, and in one patient (16.7%) it was eccentric
    explanation: These results are restricted to the six primary cases in a mixed cohort of 14; none had histopathological confirmation.
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      Although the development of HRVWI-MRI is promising, it is not validated and has not been formally compared to other diagnostic techniques in patients with PACNS.
    explanation: The guideline treats vessel-wall MRI as an adjunct with uncertain diagnostic accuracy, rather than a stand-alone test.
treatments:
- name: Glucocorticoid therapy
  description: >-
    High-dose glucocorticoids are central to induction therapy, either alone in
    selected cases or combined with additional immunosuppression for higher-risk
    disease.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: corticosteroid
      term:
        id: CHEBI:50858
        label: corticosteroid
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:25708615
    reference_title: "Adult primary central nervous system vasculitis treatment and course: analysis of one hundred sixty-three patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      A favorable response was observed in 85% of patients treated with
      prednisone alone and in 80% of patients treated with prednisone and
      cyclophosphamide.
    explanation: This cohort supports glucocorticoid-based treatment responses.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The group’s recommendations on induction and maintenance of treatment and
      for primary or secondary prevention of vascular events also reflect
      uncertainty due to lack of evidence.
    explanation: The ESO guideline supports cautious interpretation of treatment evidence.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  therapeutic_modality: SMALL_MOLECULE
- name: Glucocorticoid and cyclophosphamide induction
  description: >-
    Glucocorticoids with cyclophosphamide are commonly used for induction, particularly in severe disease. Observational Mayo and German cohorts associate cyclophosphamide-based regimens with fewer relapses. A biopsy-proven small-vessel series associated earlier cyclophosphamide with faster remission, without demonstrating a statistically significant functional benefit. Confounding by treatment selection limits causal comparisons.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: corticosteroid
      term:
        id: CHEBI:50858
        label: corticosteroid
    - preferred_term: cyclophosphamide
      term:
        id: CHEBI:4027
        label: cyclophosphamide
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:3275856
    reference_title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Therapy of PACNS with a combination of cytotoxic drugs and high-dose
      corticosteroids has greatly improved the prognosis for this condition.
    explanation: The original criteria review supports cytotoxic-drug plus high-dose corticosteroid therapy.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: PMID:26020379
    reference_title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Relapses occurred in one-quarter of the patients and were less frequent in
      patients treated with prednisone and cyclophosphamide compared with those
      treated with prednisone alone.
    explanation: The large cohort supports reduced relapse with combined prednisone and cyclophosphamide.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40546217
    reference_title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Patients treated with cyclophosphamide alone or in combination with
      steroids had a lower incidence of relapse than untreated patients
    explanation: The German cohort reports an association with fewer relapses versus untreated periods; nonrandomized treatment and confounding by indication prevent a causal efficacy conclusion.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      While patients who received EIT in this study achieved remission significantly sooner, the positive trend toward a better functional outcome with EIT was not statistically significant.
    explanation: Earlier cyclophosphamide was associated with faster remission in 26 biopsy-proven cases; improvement in functional outcomes was not statistically established.
  therapeutic_modality: SMALL_MOLECULE
- name: Mycophenolate mofetil steroid-sparing therapy
  description: >-
    Mycophenolate mofetil is an induction alternative or maintenance immunosuppressant in observational PCNSV series. Favorable disability associations in the Mayo cohort do not establish superiority to cyclophosphamide; comparative safety and relapse evidence remain limited.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: mycophenolate mofetil
      term:
        id: CHEBI:8764
        label: mycophenolate mofetil
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:25800827
    reference_title: Mycophenolate mofetil in primary central nervous system vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      MMF in combination with GCs achieved a favorable response in most
      patients.
    explanation: This PCNSV treatment cohort supports MMF with glucocorticoids.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:32062032
    reference_title: "Long-term remission, relapses and maintenance therapy in adult primary central nervous system vasculitis: A single-center 35-year experience."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Mycophenolate mofetil may be an effective alternative to CYC."
    explanation: Long-term follow-up supports MMF as a possible alternative to cyclophosphamide.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:25800827
    reference_title: Mycophenolate mofetil in primary central nervous system vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      No statistically significant differences were observed regarding relapses and ability to discontinue therapy at last follow-up.
    explanation: The Mayo comparison did not establish a relapse advantage for mycophenolate.
  therapeutic_modality: SMALL_MOLECULE
- name: Azathioprine maintenance immunosuppression
  description: >-
    Azathioprine is used as a steroid-sparing maintenance immunosuppressant in
    CNS vasculitis cohorts after induction therapy, though drug-specific
    comparative efficacy remains limited.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: azathioprine
      term:
        id: CHEBI:2948
        label: azathioprine
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      19 received maintenance immunosuppression with azathioprine (n = 9), mycophenolate mofetil (MMF, n = 7), prednisone (n = 2), or methotrexate (n = 1).
    explanation: The biopsy-proven small-vessel PACNS series documents maintenance use; it does not compare the efficacy of individual maintenance drugs.
  therapeutic_modality: SMALL_MOLECULE
- name: Rituximab for selected refractory PCNSV
  description: >-
    Rituximab is supported only by small observational series and literature
    review data, so it is best represented as a selected refractory or
    individualized therapy rather than standard first-line treatment.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: rituximab
      term:
        id: NCIT:C1702
        label: Rituximab
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:30743080
    reference_title: "Rituximab therapy for primary central nervous system vasculitis: A 6 patient experience and review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Five of the 6 were refractory to high dose glucocorticoids (GCs) and/or
      conventional immunosuppressants (IS).
    explanation: This supports rituximab use mainly in refractory PCNSV cases.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  - reference: PMID:30743080
    reference_title: "Rituximab therapy for primary central nervous system vasculitis: A 6 patient experience and review of the literature."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our data support a potential role for RTX treatment in selected patients with PCNSV."
    explanation: The authors conclude rituximab may have a selected role.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
  therapeutic_modality: MONOCLONAL_ANTIBODY
- name: Methotrexate maintenance immunosuppression
  description: >-
    Methotrexate is one steroid-sparing maintenance option after induction. PACNS-specific comparative efficacy is uncertain; its use is supported by observational experience and expert synthesis.
  therapeutic_modality: SMALL_MOLECULE
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: methotrexate
      term:
        id: CHEBI:44185
        label: methotrexate
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
  evidence:
  - reference: PMID:40334177
    reference_title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      19 received maintenance immunosuppression with azathioprine (n = 9), mycophenolate mofetil (MMF, n = 7), prednisone (n = 2), or methotrexate (n = 1).
    explanation: Methotrexate was used for maintenance in one patient in this biopsy-confirmed small-vessel cohort; this documents use, not comparative efficacy.
- name: Infliximab in selected refractory disease
  description: >-
    Infliximab has anecdotal rescue-use evidence. A child with biopsy-confirmed progressive PACNS improved after infliximab following deterioration despite glucocorticoids, intravenous immunoglobulin, cyclophosphamide and rituximab. A single sequentially treated case cannot establish efficacy, routine indications or an HLA-defined responsive subtype.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: Infliximab
      term:
        id: NCIT:C1789
        label: Infliximab
  therapeutic_modality: MONOCLONAL_ANTIBODY
  evidence:
  - reference: PMID:41283854
    reference_title: 'Rapidly progressive glucocorticoid-resistant childhood-primary angiitis of the central nervous system positive for HLA-B51 and A26: a case report.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Despite intravenous immunoglobulin, intravenous cyclophosphamide, and rituximab, the patient became comatose, and the brain MRI worsened. Following infliximab, clinical symptoms and brain MRI improved.
    explanation: This case reports clinical and imaging improvement after rescue treatment, with substantial confounding from preceding therapies.
  target_mechanisms:
  - target: CNS Vessel Wall Inflammation
    treatment_effect: INHIBITS
    description: Intended suppression of vascular inflammation in refractory disease; vessel-wall target engagement was not measured in the cited case.
    evidence:
    - reference: PMID:41283854
      reference_title: 'Rapidly progressive glucocorticoid-resistant childhood-primary angiitis of the central nervous system positive for HLA-B51 and A26: a case report.'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      quote_role: PRIMARY_RESULT
      directness: INDIRECT
      snippet: >-
        Despite intravenous immunoglobulin, intravenous cyclophosphamide, and rituximab, the patient became comatose, and the brain MRI worsened. Following infliximab, clinical symptoms and brain MRI improved.
      explanation: Improvement after rescue infliximab is consistent with its intended anti-inflammatory role; this uncontrolled case does not demonstrate a vessel-wall mechanism or establish efficacy.
differential_diagnoses:
- name: Secondary CNS vasculitis and mimics
  description: >-
    Infectious, systemic autoimmune, malignant, drug-related, and other
    neurologic causes can mimic primary CNS vasculitis and must be excluded
    before assigning the primary diagnosis.
  distinguishing_features:
  - Evidence of systemic vasculitis or another secondary cause argues against primary CNS vasculitis.
  - CSF, imaging, laboratory testing, angiography, and biopsy are used together to separate PACNS from mimics.
  evidence:
  - reference: PMID:3275856
    reference_title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      no evidence of a systemic vasculitide or any other condition to which the
      angiographic or pathologic features could be secondary.
    explanation: Exclusion of systemic or secondary causes is part of the classic PACNS criteria.
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: ORPHA:140989
    reference_title: Primary angiitis of the central nervous system
    supports: SUPPORT
    snippet: >-
      in the absence of other identified underlying cause (infectious, systemic,
      other neurologic diseases, etc.).
    explanation: Orphanet likewise defines PACNS by excluding secondary causes.
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
  - reference: DOI:10.1177/19418744231223283
    reference_title: "Vasculitis in the Central Nervous System: Etiology, Characteristics, and Outcomes in a Large Single-Center Cohort"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Compared to primary CNS vasculitis, secondary CNS vasculitis exhibits
      higher fever incidence (observed in infectious and connective tissue
      disorder [CTD]-associated vasculitis), low glucose levels (mostly in
      infectious vasculitis) and unique cerebrospinal fluid oligoclonal bands
      (observed in infectious and CTD-associated vasculitis).
    explanation: This cohort gives specific features that favor secondary CNS vasculitis over primary disease.
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: Reversible cerebral vasoconstriction syndrome
  description: >-
    RCVS can resemble angiographic PACNS. Thunderclap headache and a compatible reversible vasoconstrictive course favor RCVS; an angiographic string-of-beads pattern alone does not distinguish the two.
  distinguishing_features:
  - Thunderclap headache is a useful RCVS clue in the appropriate clinical context.
  - Angiographic beading can occur without inflammatory vasculitis.
  evidence:
  - reference: PMID:22467936
    reference_title: 'Challenging the diagnosis of primary angiitis of the central nervous system: a single-center retrospective study.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Thirteen patients had RCVS. Thunderclap headaches, the absence of a focal neurological deficit, a convexal subarachnoid hemorrhage and/or normal brain parenchyma on magnetic resonance imaging, and "string of beads" appearance on conventional angiography had high diagnostic value.
    explanation: In this referred cohort, these features favored RCVS; they are not absolute diagnostic requirements or exclusion rules.
- name: Cerebral amyloid angiopathy-related inflammation
  description: >-
    CAA-related perivascular inflammation can resemble small-vessel PACNS clinically and radiologically. Amyloid-beta-related angiitis (ABRA) has destructive inflammation within amyloid-bearing vessel walls; perivascular inflammation alone does not establish vasculitis.
  distinguishing_features:
  - Histology distinguishes destructive transmural angiitis from predominantly perivascular inflammation around amyloid-bearing vessels.
  evidence:
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: BACKGROUND
    directness: DIRECT
    snippet: >-
      Two pathologic inflammatory reactions to the deposition of amyloid-β in the cerebral vessels have been described: first with a vasculitic transmural, often granulomatous, inflammation (ABRA), and the second with a perivascular non-destructive inflammatory infiltration, so called CAA-RI.
    explanation: The discussion explicitly distinguishes transmural ABRA from nondestructive perivascular CAA-related inflammation.
  - reference: PMID:26020379
    reference_title: 'An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Mild perivascular inflammation often with giant cells surrounding leptomeningeal and cortical small vessels (upper; H&E stain) with vascular amyloid deposition (lower; immunoperoxidase stain for βA4 amyloid) is characteristic of CAA-RI.
    explanation: Perivascular inflammation in CAA-RI is distinguished from destructive transmural ABRA.
clinical_trials:
- name: NCT03166319
  phase: NOT_APPLICABLE
  status: COMPLETED
  description: Prospective pilot study of MRI and high-resolution intracranial vessel wall imaging for diagnosis and disease-activity assessment in suspected CNS vasculitis.
  evidence:
  - reference: clinicaltrials:NCT03166319
    reference_title: The Utility of Intracranial Vessel Wall Imaging for Suspected CNS Vasculitis Diagnosis and Assessment of Disease Activity.
    supports: SUPPORT
    snippet: >-
      This is a prospective pilot study to determine the utility of MRI and high
      resolution intracranial vessel wall imaging for the diagnosis and disease
      activity assessment of intracranial vasculitis.
    explanation: The trial directly studies vessel-wall imaging in suspected CNS vasculitis.
    evidence_source: OTHER
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: NCT05168475
  phase: PHASE_II
  status: TERMINATED
  description: >-
    Phase 2 randomized trial of biologic therapy in refractory primary non-ANCA-associated vasculitis, a broader population than PACNS. The registry reports termination because NIHR withdrew funding. Registration and pooled trial results do not establish PACNS-specific efficacy.
  evidence:
  - reference: clinicaltrials:NCT05168475
    reference_title: "Biologics in Refractory Vasculitis (BIOVAS): A Pragmatic, Randomised, Double-blind, Placebo-controlled, Modified-crossover Trial of Biologic Therapy for Refractory Primary Non-ANCA Associated Vasculitis in Adults and Children"
    supports: SUPPORT
    snippet: >-
      The trial will include patients with Non-ANCA-associated vasculitis
      (NAAV)
    explanation: The trial is relevant to refractory non-ANCA vasculitis but is not specific to primary CNS vasculitis.
    evidence_source: OTHER
    quote_role: PRIMARY_RESULT
    directness: DIRECT
- name: NCT00659776
  phase: PHASE_II
  status: TERMINATED
  description: >-
    Phase 2 exploratory ferumoxytol MRI study for a broad range of CNS inflammatory and vascular lesions, including vasculitis. The registry reports termination because of staffing shortages and lack of funding during COVID. This is a diagnostic imaging study, not a PACNS treatment efficacy trial.
  evidence:
  - reference: clinicaltrials:NCT00659776
    reference_title: "Multi-Disciplinary Study: Magnetic Resonance, Histologic And Electron Microscopy Imaging Of Intravenous Superparamagnetic Crystalline Particles (Ferumoxytol) In CNS Inflammation"
    supports: SUPPORT
    snippet: >-
      The protocol enrolls subjects with radiological or histological diagnosis
      of unknown, dural, or parenchymal CNS lesions, multiple sclerosis, TIA or
      stroke, vasculitis, or other vascular lesions
    explanation: The imaging study includes vasculitis among broader CNS inflammatory and vascular indications.
    evidence_source: OTHER
    quote_role: PRIMARY_RESULT
    directness: DIRECT
references:
- reference: DOI:10.1007/s00415-026-13727-y
  title: "Primary central nervous system vasculitis: an update"
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: DOI:10.1038/s41598-024-55222-2
  title: "The role of susceptibility-weighted imaging &amp; contrast-enhanced MRI in the diagnosis of primary CNS vasculitis: a large case series"
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: DOI:10.1177/19418744231223283
  title: "Vasculitis in the Central Nervous System: Etiology, Characteristics, and Outcomes in a Large Single-Center Cohort"
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: PMID:37903069
  title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: DOI:10.1212/cpj.0000000000200321
  title: Predictive Value of Clinical, CSF and Vessel Wall MRI Variables in Diagnosing Primary Angiitis of the CNS
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: PMID:40334177
  title: 'Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.'
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: DOI:10.3389/fneur.2024.1363985
  title: "Primary CNS vasculitis: insights into clinical, neuropathological, and neuroradiological characteristics"
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: DOI:10.3389/fneur.2025.1602427
  title: "Comparison between primary and secondary central nervous system vasculitis in terms of clinical, biochemical, radiological, histopathological features, and outcomes: a single-center retrospective cohort study"
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: PMID:38732340
  title: The Contribution of Vessel Wall Magnetic Resonance Imaging to the Diagnosis of Primary and Secondary Central Nervous System Vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-falcon.md
  findings: []
- reference: PMID:41947889
  title: "Overview of Primary Angiitis of the Central Nervous System: Current Insights."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:34663675
  title: "Primary Angiitis of the CNS: A Systematic Review and Meta-analysis."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:40546217
  title: Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:36264136
  title: Exploring Gene Expression Profiles in Primary Central Nervous System Vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:37151140
  title: "Inflammatory Cerebral Amyloid Angiopathy: A Broad Clinical Spectrum."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:24636849
  title: Amyloid beta-related angiitis--a case report and comprehensive review of literature of 94 cases.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:41041677
  title: "Size of affected vessels in primary angiitis of the CNS: associations with clinical features, medical management and functional outcomes."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:41479923
  title: "A comparative study of large-vessel and small-vessel primary angiitis of the central nervous system: insights from a Chinese single-center retrospective cohort."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:30789149
  title: Long-term outcomes of patients with primary angiitis of the central nervous system.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:30762375
  title: Cognitive outcomes of childhood primary CNS vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:39979764
  title: Spinal cord involvement in primary central nervous system vasculitis. A systematic review of clinical, neuroradiological and pathological findings.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:39732702
  title: Towards a histological diagnosis of childhood small vessel CNS vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:28330942
  title: "Primary Angiitis of the Central Nervous System: Magnetic Resonance Imaging Spectrum of Parenchymal, Meningeal, and Vascular Lesions at Baseline."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:40643487
  title: Neurofilament Light Chain in Serum and CSF as a Potential Biomarker for Primary Angiitis of the Central Nervous System.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:31211179
  title: CSF Neurofilament light chain level predicts axonal damage in cerebral vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:32296382
  title: Circulating Endothelial Cells as Promising Biomarkers in the Differential Diagnosis of Primary Angiitis of the Central Nervous System.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:40835417
  title: "Unilateral Primary Angiitis of the Central Nervous System: A Rare and Under-Recognized Entity."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:38900992
  title: "Cerebral Amyloid Angiopathy-Related Inflammation and Biopsy-Positive Primary Angiitis of the CNS: A Comparative Study."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:35931755
  title: "Primary CNS vasculitis (PCNSV): a cohort study."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:40494617
  title: "Biopsy-proven PACNS: results from the large, multicentre cohort of cerebral vasculitis patients."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:23622312
  title: Childhood central nervous system vasculitis.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:25877722
  title: CNS vasculitis in children.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:29030476
  title: Added Value of Vessel Wall Magnetic Resonance Imaging for Differentiation of Nonocclusive Intracranial Vasculopathies.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:37073640
  title: Clinical characteristics, brain magnetic resonance imaging findings and diagnostic approach of the primary central nervous system vasculitis according to angiographic classification.
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:32776287
  title: "When should primary angiitis of the central nervous system (PACNS) be suspected?\": literature review and proposal of a preliminary screening algorithm."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:22467936
  title: "Challenging the diagnosis of primary angiitis of the central nervous system: a single-center retrospective study."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:41112399
  title: "Tumefactive primary angiitis of the central nervous system mimicking glioblastoma: A case-based systematic review."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:41718297
  title: "SLIPPERS Reconsidered: Clinical, Radiological, and Pathological Overlap with PACNS-A Case Report."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:41995257
  title: "Treatment Response and Prognosis of Primary Angiitis of the Central Nervous System: A Real-World Observation."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:39954605
  title: "Combination therapy with cyclophosphamide, rituximab and corticosteroids in order to arrest a rapidly progressive primary CNS vasculitis: a case report with 40-month follow-up remission."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:28034820
  title: "Mycophenolate mofetil as induction and long-term maintaining treatment in childhood: Primary angiitis of the central nervous system."
  found_in:
  - CNS_Vasculitis-deep-research-openscientist.md
  findings: []
- reference: PMID:26020379
  title: "An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients."
- reference: PMID:18753193
  title: "Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy."
- reference: PMID:18240248
  title: "Primary central nervous system vasculitis with prominent leptomeningeal enhancement: a subset with a benign outcome."
- reference: PMID:40110603
  title: "PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study."
- reference: PMID:3275856
  title: "Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria."
- reference: PMID:17924545
  title: "Primary central nervous system vasculitis: analysis of 101 patients."
- reference: PMID:32062032
  title: "Long-term remission, relapses and maintenance therapy in adult primary central nervous system vasculitis: A single-center 35-year experience."
- reference: PMID:25708615
  title: "Adult primary central nervous system vasculitis treatment and course: analysis of one hundred sixty-three patients."
- reference: PMID:30860105
  title: "Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients."
- reference: PMID:25800827
  title: Mycophenolate mofetil in primary central nervous system vasculitis.
- reference: PMID:30743080
  title: "Rituximab therapy for primary central nervous system vasculitis: A 6 patient experience and review of the literature."
- reference: PMID:41283854
  title: 'Rapidly progressive glucocorticoid-resistant childhood-primary angiitis of the central nervous system positive for HLA-B51 and A26: a case report.'
- reference: PMID:27144213
  title: IL-17 production by CSF lymphocytes as a biomarker for cerebral vasculitis.
- reference: PMID:31270218
  title: Exploratory proteomic analysis implicates the alternative complement cascade in primary CNS vasculitis.
- reference: PMID:34066885
  title: Profiling Complement System Components in Primary CNS Vasculitis.
- reference: PMID:40026305
  title: Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Changes in Primary Angiitis of the Central Nervous System.
datasets:
- accession: geo:GSE213907
  title: EXPLORING GENE EXPRESSION PROFILES IN PRIMARY CENTRAL NERVOUS SYSTEM VASCULITIS
  description: >-
    Bulk RNA sequencing of brain specimens from primary CNS vasculitis and controls, associated with Salvarani et al. (PMID:36264136).
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 17
  notes: >-
    The 17 specimens comprise four granulomatous vasculitis cases, five lymphocytic vasculitis cases, four amyloid-beta-related angiitis cases, and four controls. Pathway and immune-cell deconvolution analyses are exploratory; the dataset is not a functional perturbation experiment.
biochemical:
- name: Circulating endothelial cells
  presence: Increased in active disease
  notes: >-
    Immunomagnetic enumeration found higher peripheral-blood CEC counts in seven active PACNS cases than in 20 remission cases, 13 healthy controls and seven RCVS/moyamoya cases. CECs also rose in the noninflammatory vasculopathy controls. This is a candidate vascular-injury biomarker; the small study and data-derived cutoff do not establish clinical diagnostic accuracy.
  cell_types:
  - preferred_term: endothelial cell
    term:
      id: CL:0000115
      label: endothelial cell
  evidence:
  - reference: PMID:32296382
    reference_title: Circulating Endothelial Cells as Promising Biomarkers in the Differential Diagnosis of Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Patients with an active PACNS showed significantly higher CEC levels (480 CEC/ml, 304–1552) than PACNS patients in remission (54 CEC/ml, 4–100; p < 0.001, Figure 2) and also compared to healthy subjects (40 CEC/ml, 8–52; p < 0.001).
    explanation: The study measured increased CEC counts during active disease.
  - reference: PMID:32296382
    reference_title: Circulating Endothelial Cells as Promising Biomarkers in the Differential Diagnosis of Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      In patients with RCVS/MMD, CECs were also significantly elevated (288 CEC/ml, 184–352) compared to healthy controls (p < 0.001), but they were still significantly lower when compared to patients with an active PACNS (p = 0.017).
    explanation: Elevation also occurs in noninflammatory vasculopathies, limiting disease specificity.
- name: IL-17 production by cultured CSF CD4 T cells
  presence: Increased after expansion and stimulation
  notes: >-
    A small study including six PACNS patients found an increased fraction of IL-17-producing CSF-derived CD4 T cells after 2–4 weeks of expansion and stimulation. Soluble CSF IL-17 was generally undetectable. This assay is exploratory and does not establish constitutive in vivo IL-17 elevation or efficacy of IL-17 blockade in PACNS.
  evidence:
  - reference: PMID:27144213
    reference_title: IL-17 production by CSF lymphocytes as a biomarker for cerebral vasculitis.
    supports: SUPPORT
    evidence_source: IN_VITRO
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Interestingly, all samples with CSF cells analyzed of patients with PACNS and SACNS groups showed high levels of IL-17-producing CD4+ cells (average 8.8%, range 7.3%–10.5%, for PACNS; average 10.4%, range 8.9%–11.9%, for SACNS).
    explanation: The primary-disease subgroup signal was measured in cultured CSF-derived cells.
  - reference: PMID:27144213
    reference_title: IL-17 production by CSF lymphocytes as a biomarker for cerebral vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      We also assessed soluble IL-17 in the CSF of our patients using the highly sensitive MSD platform. All values were under detection levels, except for one patient where CSF was taken shortly before he died of a fulminant vasculitis
    explanation: Direct CSF cytokine measurement does not support generalized soluble IL-17 elevation.
discussions:
- discussion_id: complement-activation
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: Does localized complement activation contribute to primary CNS vascular injury?
  rationale: >-
    CSF proteomics in eight biopsy-confirmed cases found altered complement-protein abundance, but a subsequent 20-patient study found no increased CSF or serum complement activation products. Protein abundance and activation are different measurements. A local endothelial mechanism remains unresolved; these studies do not establish a complement-targeted treatment for PACNS.
  evidence:
  - reference: PMID:31270218
    reference_title: Exploratory proteomic analysis implicates the alternative complement cascade in primary CNS vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Compared to noninflammatory controls, 283 proteins were differentially expressed in the CSF of patients with PACNS, with significant enrichment of the complement cascade pathway (C4-binding protein, CD55, CD59, properdin, complement C5, complement C8, and complement C9) and neural cell adhesion molecules.
    explanation: Exploratory proteomics identified complement-associated protein changes.
  - reference: PMID:34066885
    reference_title: Profiling Complement System Components in Primary CNS Vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      While we did not find any evidence for enhanced complement activation in the CSF of patients with PACNS, our study has limitations which should be accounted for when interpreting the results.
    explanation: The later study did not reproduce the proposed activation signal.
  - reference: PMID:34066885
    reference_title: Profiling Complement System Components in Primary CNS Vasculitis.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Our study does not formally exclude that complement activation in PACNS occurs on the endothelium in situ without being detectable in the CSF.
    explanation: The authors distinguish absence of a fluid activation signal from exclusion of localized vascular activation.
- discussion_id: metabolic-biomarker-validation
  kind: KNOWLEDGE_GAP
  status: OPEN
  prompt: Do exploratory plasma metabolic signatures reliably identify PACNS or its activity?
  rationale: >-
    A 35-patient plasma metabolomics study reported energy, amino-acid and lipid pathway associations and reused five lymphocytic PACNS and four control brain transcriptomes from GSE213907. External validation is lacking. Metabolite abundance and pathway enrichment do not directly measure metabolic flux or establish a causal metabolic driver of vasculitis.
  evidence:
  - reference: PMID:40026305
    reference_title: Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Changes in Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Additionally, external validation is lacking for the applicability of the biomarkers for clinical diagnosis.
    explanation: The study explicitly identifies the translational validation gap.
  - reference: PMID:40026305
    reference_title: Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Changes in Primary Angiitis of the Central Nervous System.
    supports: SUPPORT
    evidence_source: COMPUTATIONAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      In Cohort 2, we evaluated brain tissue transcriptomic information from five patients with PACNS and four control patients, and 844 differentially expressed genes were detected, with 741 upregulated and 103 and downregulated genes.
    explanation: The transcriptomic comparison is small and reuses a subset of the existing dataset.
imaging_findings:
- name: Vasogenic cerebral edema
  modality: MRI
  description: >-
    MRI may show vasogenic edema surrounding inflammatory lesions, sometimes with local mass effect. This finding is nonspecific and does not establish vasculitis.
  located_in:
    preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: DOI:10.3389/fneur.2024.1363985
    reference_title: 'Primary CNS vasculitis: insights into clinical, neuropathological, and neuroradiological characteristics'
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    quote_role: PRIMARY_RESULT
    directness: DIRECT
    snippet: >-
      Three patients demonstrated unilateral involvement with T2 hyperintensity and vasogenic edema surrounding the lesions, resulting in a local mass effect on fissures, gyrus, and ventricles
    explanation: The five-patient primary CNS vasculitis series documents edema and local mass effect on MRI.
- name: Pseudotumoral inflammatory brain lesions
  modality: MRI
  description: >-
    A minority of PACNS cases present with mass-like inflammatory lesions that can mimic neoplasm. The ESO synthesis reported a pseudotumoral pattern in 27 of 660 patients, while noting probable underreporting.
  located_in:
    preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:37903069
    reference_title: European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
    supports: SUPPORT
    evidence_source: OTHER
    quote_role: REVIEW_SYNTHESIS
    directness: DIRECT
    snippet: >-
      A pseudotumoral pattern was reported in a minority of patients (27/660 or 4.1%). This pattern was also likely to be underreported, but, in single institution case series, it was rare.
    explanation: The guideline describes an uncommon tumor-like imaging presentation rather than a neoplastic diagnosis.
📚

References & Deep Research

References

56
DOI:10.1007/s00415-026-13727-y
Primary central nervous system vasculitis: an update
No top-level findings curated for this source.
DOI:10.1038/s41598-024-55222-2
The role of susceptibility-weighted imaging &amp; contrast-enhanced MRI in the diagnosis of primary CNS vasculitis: a large case series
No top-level findings curated for this source.
DOI:10.1177/19418744231223283
Vasculitis in the Central Nervous System: Etiology, Characteristics, and Outcomes in a Large Single-Center Cohort
No top-level findings curated for this source.
PMID:37903069
European Stroke Organisation (ESO) guidelines on Primary Angiitis of the Central Nervous System (PACNS).
No top-level findings curated for this source.
DOI:10.1212/cpj.0000000000200321
Predictive Value of Clinical, CSF and Vessel Wall MRI Variables in Diagnosing Primary Angiitis of the CNS
No top-level findings curated for this source.
PMID:40334177
Biopsy-Confirmed Small Vessel Primary CNS Vasculitis: Clinical Features and Impact of Early Intensive Treatment on Remission.
No top-level findings curated for this source.
DOI:10.3389/fneur.2024.1363985
Primary CNS vasculitis: insights into clinical, neuropathological, and neuroradiological characteristics
No top-level findings curated for this source.
DOI:10.3389/fneur.2025.1602427
Comparison between primary and secondary central nervous system vasculitis in terms of clinical, biochemical, radiological, histopathological features, and outcomes: a single-center retrospective cohort study
No top-level findings curated for this source.
PMID:38732340
The Contribution of Vessel Wall Magnetic Resonance Imaging to the Diagnosis of Primary and Secondary Central Nervous System Vasculitis.
No top-level findings curated for this source.
PMID:41947889
Overview of Primary Angiitis of the Central Nervous System: Current Insights.
No top-level findings curated for this source.
PMID:34663675
Primary Angiitis of the CNS: A Systematic Review and Meta-analysis.
No top-level findings curated for this source.
PMID:40546217
Disease Characteristics and Treatments Associated with Outcome in Primary Angiitis of the Central Nervous System-A Multicenter Cohort Study in 163 Patients.
No top-level findings curated for this source.
PMID:36264136
Exploring Gene Expression Profiles in Primary Central Nervous System Vasculitis.
No top-level findings curated for this source.
PMID:37151140
Inflammatory Cerebral Amyloid Angiopathy: A Broad Clinical Spectrum.
No top-level findings curated for this source.
PMID:24636849
Amyloid beta-related angiitis--a case report and comprehensive review of literature of 94 cases.
No top-level findings curated for this source.
PMID:41041677
Size of affected vessels in primary angiitis of the CNS: associations with clinical features, medical management and functional outcomes.
No top-level findings curated for this source.
PMID:41479923
A comparative study of large-vessel and small-vessel primary angiitis of the central nervous system: insights from a Chinese single-center retrospective cohort.
No top-level findings curated for this source.
PMID:30789149
Long-term outcomes of patients with primary angiitis of the central nervous system.
No top-level findings curated for this source.
PMID:30762375
Cognitive outcomes of childhood primary CNS vasculitis.
No top-level findings curated for this source.
PMID:39979764
Spinal cord involvement in primary central nervous system vasculitis. A systematic review of clinical, neuroradiological and pathological findings.
No top-level findings curated for this source.
PMID:39732702
Towards a histological diagnosis of childhood small vessel CNS vasculitis.
No top-level findings curated for this source.
PMID:28330942
Primary Angiitis of the Central Nervous System: Magnetic Resonance Imaging Spectrum of Parenchymal, Meningeal, and Vascular Lesions at Baseline.
No top-level findings curated for this source.
PMID:40643487
Neurofilament Light Chain in Serum and CSF as a Potential Biomarker for Primary Angiitis of the Central Nervous System.
No top-level findings curated for this source.
PMID:31211179
CSF Neurofilament light chain level predicts axonal damage in cerebral vasculitis.
No top-level findings curated for this source.
PMID:32296382
Circulating Endothelial Cells as Promising Biomarkers in the Differential Diagnosis of Primary Angiitis of the Central Nervous System.
No top-level findings curated for this source.
PMID:40835417
Unilateral Primary Angiitis of the Central Nervous System: A Rare and Under-Recognized Entity.
No top-level findings curated for this source.
PMID:38900992
Cerebral Amyloid Angiopathy-Related Inflammation and Biopsy-Positive Primary Angiitis of the CNS: A Comparative Study.
No top-level findings curated for this source.
PMID:35931755
Primary CNS vasculitis (PCNSV): a cohort study.
No top-level findings curated for this source.
PMID:40494617
Biopsy-proven PACNS: results from the large, multicentre cohort of cerebral vasculitis patients.
No top-level findings curated for this source.
PMID:23622312
Childhood central nervous system vasculitis.
No top-level findings curated for this source.
PMID:25877722
CNS vasculitis in children.
No top-level findings curated for this source.
PMID:29030476
Added Value of Vessel Wall Magnetic Resonance Imaging for Differentiation of Nonocclusive Intracranial Vasculopathies.
No top-level findings curated for this source.
PMID:37073640
Clinical characteristics, brain magnetic resonance imaging findings and diagnostic approach of the primary central nervous system vasculitis according to angiographic classification.
No top-level findings curated for this source.
PMID:32776287
When should primary angiitis of the central nervous system (PACNS) be suspected?": literature review and proposal of a preliminary screening algorithm.
No top-level findings curated for this source.
PMID:22467936
Challenging the diagnosis of primary angiitis of the central nervous system: a single-center retrospective study.
No top-level findings curated for this source.
PMID:41112399
Tumefactive primary angiitis of the central nervous system mimicking glioblastoma: A case-based systematic review.
No top-level findings curated for this source.
PMID:41718297
SLIPPERS Reconsidered: Clinical, Radiological, and Pathological Overlap with PACNS-A Case Report.
No top-level findings curated for this source.
PMID:41995257
Treatment Response and Prognosis of Primary Angiitis of the Central Nervous System: A Real-World Observation.
No top-level findings curated for this source.
PMID:39954605
Combination therapy with cyclophosphamide, rituximab and corticosteroids in order to arrest a rapidly progressive primary CNS vasculitis: a case report with 40-month follow-up remission.
No top-level findings curated for this source.
PMID:28034820
Mycophenolate mofetil as induction and long-term maintaining treatment in childhood: Primary angiitis of the central nervous system.
No top-level findings curated for this source.
PMID:26020379
An update of the Mayo Clinic cohort of patients with adult primary central nervous system vasculitis: description of 163 patients.
No top-level findings curated for this source.
PMID:18753193
Primary central nervous system vasculitis: comparison of patients with and without cerebral amyloid angiopathy.
No top-level findings curated for this source.
PMID:18240248
Primary central nervous system vasculitis with prominent leptomeningeal enhancement: a subset with a benign outcome.
No top-level findings curated for this source.
PMID:40110603
PCNSV With Spinal Cord Involvement: A 40-Year Single-Center Study.
No top-level findings curated for this source.
PMID:3275856
Primary angiitis of the central nervous system. Report of 8 new cases, review of the literature, and proposal for diagnostic criteria.
No top-level findings curated for this source.
PMID:17924545
Primary central nervous system vasculitis: analysis of 101 patients.
No top-level findings curated for this source.
PMID:32062032
Long-term remission, relapses and maintenance therapy in adult primary central nervous system vasculitis: A single-center 35-year experience.
No top-level findings curated for this source.
PMID:25708615
Adult primary central nervous system vasculitis treatment and course: analysis of one hundred sixty-three patients.
No top-level findings curated for this source.
PMID:30860105
Primary angiitis of the central nervous system: Clinical profiles and outcomes of 45 patients.
No top-level findings curated for this source.
PMID:25800827
Mycophenolate mofetil in primary central nervous system vasculitis.
No top-level findings curated for this source.
PMID:30743080
Rituximab therapy for primary central nervous system vasculitis: A 6 patient experience and review of the literature.
No top-level findings curated for this source.
PMID:41283854
Rapidly progressive glucocorticoid-resistant childhood-primary angiitis of the central nervous system positive for HLA-B51 and A26: a case report.
No top-level findings curated for this source.
PMID:27144213
IL-17 production by CSF lymphocytes as a biomarker for cerebral vasculitis.
No top-level findings curated for this source.
PMID:31270218
Exploratory proteomic analysis implicates the alternative complement cascade in primary CNS vasculitis.
No top-level findings curated for this source.
PMID:34066885
Profiling Complement System Components in Primary CNS Vasculitis.
No top-level findings curated for this source.
PMID:40026305
Integrated Metabolomics and Transcriptomics Analyses Reveal Metabolic Changes in Primary Angiitis of the Central Nervous System.
No top-level findings curated for this source.

Deep Research

2

Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.

Falcon ▸
Recent developments (2023–2024 highlights)
Edison Scientific Literature 37 citations 2026-05-16T03:32:20.954002

1. Disease Information

1.1 What is the disease? (concise overview)

Primary angiitis of the CNS (PACNS/PCNSV) is a rare inflammatory disorder of CNS blood vessels that is restricted to the brain/spinal cord/meninges (i.e., no systemic vasculitis) and presents with heterogeneous neurologic syndromes such as headache, encephalopathy, stroke syndromes, and seizures. (pascarella2023europeanstrokeorganisation pages 1-2, sheikh2024primarycnsvasculitis pages 1-2, hoshina2024vasculitisinthe pages 1-2)

Authoritative definition/clinical framing (ESO guideline, Oct 2023): PACNS is treated as an isolated CNS vasculitis with very low-quality evidence across many diagnostic/treatment questions; histopathology is emphasized as the diagnostic reference standard and there is no single specific neuroimaging pattern. (pascarella2023europeanstrokeorganisation pages 1-2)

1.2 Key identifiers and codes

Only some coding/identifier systems were explicitly present in the retrieved sources:

  • ICD-9: 437.4 (reported as used for case identification in a CNS vasculitis cohort). (hoshina2024vasculitisinthe pages 2-3)
  • ICD-10: I67.7 “Cerebral arteritis, not elsewhere classified” (reported as used for case identification). (hoshina2024vasculitisinthe pages 2-3)

Not found in retrieved evidence: MONDO ID, MeSH ID, Orphanet ID, OMIM ID, ICD-11 code. (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 2-3)

1.3 Synonyms / alternative names

Common synonyms used in the recent literature include: - PACNS = “Primary angiitis of the central nervous system” (ESO guideline terminology). (pascarella2023europeanstrokeorganisation pages 1-2) - PCNSV/PCNSV = “Primary CNS vasculitis” (used interchangeably in 2024 clinical/imaging series). (sheikh2024primarycnsvasculitis pages 1-2, d’aniello2024thecontributionof pages 1-2) - Subclassification terms (especially in guidelines): LV-PACNS (large/medium vessel predominant) and SV-PACNS (small-vessel predominant). (pascarella2023europeanstrokeorganisation pages 1-2)

1.4 Evidence source type (patient vs aggregated)

The retrieved evidence is primarily aggregated disease-level resources (ESO guideline) plus retrospective single-center cohorts/series and imaging-focused case series (human clinical). (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 2-3, d’aniello2024thecontributionof pages 1-2, agarwal2024theroleof pages 11-12)

Identifier/synonym summary table

Concept Identifier system Identifier/code Notes/source
Primary angiitis of the central nervous system Preferred disease name in guideline/literature PACNS Used as the main term in the 2023 European Stroke Organisation guideline title and throughout the retrieved CNS vasculitis literature; primary form is defined as isolated CNS vasculitis without systemic disease (https://doi.org/10.1177/23969873231190431; Oct 2023) (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
Primary CNS vasculitis Synonym / literature term PCNSV Used synonymously with PACNS in 2024-2026 retrieved studies/reviews; D’Aniello 2024 and Sheikh 2024 use “primary CNS vasculitis/PCNSV” for the primary form (https://doi.org/10.3390/diagnostics14090927; Apr 2024; https://doi.org/10.3389/fneur.2024.1363985; Apr 2024) (sheikh2024primarycnsvasculitis pages 1-2, d’aniello2024thecontributionof pages 1-2)
CNS vasculitis Broad disease term CNSV Broad umbrella term covering primary and secondary CNS vasculitis; Hoshina 2024 explicitly stratified cases into primary and secondary CNS vasculitis (https://doi.org/10.1177/19418744231223283; Dec 2024) (hoshina2024vasculitisinthe pages 2-3, hoshina2024vasculitisinthe pages 1-2)
Primary CNS vasculitis / primary angiitis of the CNS Diagnostic category (Birnbaum & Hellmann framework cited in cohort) Definite / Probable Hoshina 2024 notes PACNS is “definite” with tissue confirmation and “probable” without biopsy if imaging/CSF are supportive; ESO 2023 emphasizes histopathology as gold standard (https://doi.org/10.1177/19418744231223283; Dec 2024; https://doi.org/10.1177/23969873231190431; Oct 2023) (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
Large-vessel primary angiitis of the CNS Guideline subclassification LV-PACNS ESO 2023 explicitly distinguishes LV-PACNS from SV-PACNS (https://doi.org/10.1177/23969873231190431; Oct 2023) (pascarella2023europeanstrokeorganisation pages 1-2)
Small-vessel primary angiitis of the CNS Guideline subclassification SV-PACNS ESO 2023 explicitly distinguishes SV-PACNS from LV-PACNS (https://doi.org/10.1177/23969873231190431; Oct 2023) (pascarella2023europeanstrokeorganisation pages 1-2)
Secondary CNS vasculitis Disease category / comparator SCNSV / SACNS Retrieved sources use both SCNSV and SACNS for vasculitis secondary to infection, connective tissue disease, malignancy, or systemic vasculitis (https://doi.org/10.3390/diagnostics14090927; Apr 2024; https://doi.org/10.3389/fneur.2025.1602427; Oct 2025) (scoppettuolo2025comparisonbetweenprimary pages 1-2, d’aniello2024thecontributionof pages 1-2)
Inflammatory cerebral amyloid angiopathy Primary CNS vasculitis-related entity in cohort inflammatory CAA Hoshina 2024 describes inflammatory CAA, including ABRA, as a primary CNS vasculitis entity with distinct biopsy features (https://doi.org/10.1177/19418744231223283; Dec 2024) (hoshina2024vasculitisinthe pages 1-2)
Amyloid-beta related angiitis Synonym / subtype label ABRA Included within inflammatory CAA/small-vessel predominant primary CNS vasculitis in retrieved cohort evidence (https://doi.org/10.1212/nxi.0000000000200397; Jul 2025; https://doi.org/10.1177/19418744231223283; Dec 2024) (hoshina2024vasculitisinthe pages 1-2)
CNS vasculitis ICD-9 437.4 Explicitly reported in Hoshina 2024 as an ICD code used for case identification (https://doi.org/10.1177/19418744231223283; Dec 2024) (hoshina2024vasculitisinthe pages 2-3)
Cerebral arteritis, not elsewhere classified ICD-10 I67.7 Explicitly reported in Hoshina 2024 as an ICD-10 code used for CNS vasculitis case identification (https://doi.org/10.1177/19418744231223283; Dec 2024) (hoshina2024vasculitisinthe pages 2-3)
CNS vasculitis / PACNS MeSH not found in retrieved sources No MeSH identifier was explicitly present in the provided evidence (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
CNS vasculitis / PACNS MONDO not found in retrieved sources No MONDO identifier was explicitly present in the provided evidence (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
CNS vasculitis / PACNS Orphanet not found in retrieved sources No Orphanet identifier was explicitly present in the provided evidence (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
CNS vasculitis / PACNS OMIM not found in retrieved sources No OMIM identifier was explicitly present in the provided evidence (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)
CNS vasculitis / PACNS ICD-11 not found in retrieved sources No ICD-11 code was explicitly present in the provided evidence (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 1-2)

Table: This table compiles the disease names, abbreviations, coding systems, and terminology explicitly documented in the retrieved evidence for CNS vasculitis and PACNS/PCNSV. It is useful for normalizing nomenclature and identifying which ontology identifiers were or were not available from the current evidence set.

2. Etiology

2.1 Disease causal factors

  • Primary CNS vasculitis (PACNS/PCNSV): by definition, vasculitic inflammation restricted to CNS vessels without an identified systemic cause. (scoppettuolo2025comparisonbetweenprimary pages 1-2, hoshina2024vasculitisinthe pages 1-2)
  • Secondary CNS vasculitis (SCNSV/SACNS): inflammation of CNS vessels secondary to another condition, including infection and connective tissue disease (CTD)-associated causes in 2024 cohort data. (hoshina2024vasculitisinthe pages 2-3, scoppettuolo2025comparisonbetweenprimary pages 1-2)

Large single-center cohort etiology breakdown (University of Utah, 2011–2022; n=44): - Primary CNS vasculitis overall: 56.8% - PACNS: 17/44 (38.6%) - Inflammatory cerebral amyloid angiopathy (CAA; includes ABRA): 8/44 (18.2%) - Secondary CNS vasculitis: 43.2% - Infectious: 10/44 (22.7%) - CTD-associated: 6/44 (13.6%) - Systemic vasculitis: 3/44 (6.8%) (hoshina2024vasculitisinthe pages 1-2)

2.2 Risk factors

The retrieved sources emphasize diagnostic differentiation rather than enumerating prospective risk factors. However, secondary disease signals are reported: - Fever occurred more often in secondary than primary CNS vasculitis (0% vs 26.3%; p=0.01), supporting infection/CTD suspicion when systemic features are present. (hoshina2024vasculitisinthe pages 2-3)

2.3 Protective factors / gene–environment interactions

Not identified in retrieved sources.

3. Phenotypes

3.1 Core clinical phenotypes (adult cohorts/series)

Across the recent adult cohort/series literature: - In a 44-patient CNS vasculitis cohort, common presenting features were headache (63.6%), altered cognition (43.2%), and focal weakness (38.6%). (hoshina2024vasculitisinthe pages 2-3) - A 2024 PCNSV single-center series emphasizes heterogeneous presentations including headache, seizures, cognitive impairment, and delayed diagnosis (median symptom duration 36 weeks before diagnosis in that series). (sheikh2024primarycnsvasculitis pages 1-2)

3.2 Imaging-linked phenotypes (high-yield patterns in 2024 imaging studies)

  • Biopsy-proven PCNSV (n=56): SWI hemorrhages in 96.4% (54/56) and parenchymal enhancement in 96.3% (52/54), with dot-linear enhancement being the most prevalent enhancement pattern (87%). (agarwal2024theroleof pages 11-12)
  • HR vessel-wall imaging cohort (n=14) included mostly stroke-like presentations (78.7% stroke-like episodes). (d’aniello2024thecontributionof pages 2-4)

3.3 Quality-of-life / disability signals

In the 2024 PCNSV series (n=5), most patients required walking aids initially and some required them at follow-up, illustrating persistent disability in a subset despite immunotherapy. (sheikh2024primarycnsvasculitis pages 1-2)

3.4 Suggested HPO terms

A phenotype-to-HPO mapping table (with frequencies where available from recent cohorts) is provided below.

Phenotype (plain language) Suggested HPO term (name; HP:ID if known) Frequency/statistics Notes/citations
Headache Headache; HP:0002315 63.6% in a 44-patient CNS vasculitis cohort; 76.9% in biopsy-confirmed small-vessel PCNSV; in a 5-patient PCNSV series, 1 presented with headache and all reported progressive holocephalic headaches Common presenting symptom across primary/secondary CNS vasculitis and small-vessel PCNSV; also highlighted as a predictor in PACNS vs ICAD analyses (hoshina2024vasculitisinthe pages 2-3, sheikh2024primarycnsvasculitis pages 1-2, kharal2024predictivevalueof pages 1-2)
Altered cognition / encephalopathy / altered mental status Encephalopathy; HP:0001298 Altered cognition in 43.2% of 44-patient cohort; altered mental status in 61.5% of sv-PCNSV cohort; encephalopathy significantly associated with PACNS vs ICAD, OR 7.60 Reflects diffuse CNS dysfunction and is repeatedly emphasized in PACNS presentations (hoshina2024vasculitisinthe pages 2-3, sheikh2024primarycnsvasculitis pages 1-2, kharal2024predictivevalueof pages 1-2)
Focal weakness / unilateral weakness Hemiparesis; HP:0001269 Focal weakness in 38.6% of 44-patient cohort; unilateral weakness in 2/5 patients in one 2024 series Typical focal neurologic deficit in PACNS presentations (hoshina2024vasculitisinthe pages 2-3, sheikh2024primarycnsvasculitis pages 1-2)
Seizures Seizure; HP:0001250 1/5 patients in Sheikh 2024; PACNS patients had seizures more often than secondary CNS vasculitis in 2025 cohort (40% vs 5%); seizure strongly associated with PACNS vs ICAD, OR 23.00 Recurrent expert signal for PACNS, especially tumor-like and inflammatory presentations (sheikh2024primarycnsvasculitis pages 1-2, scoppettuolo2025comparisonbetweenprimary pages 1-2, kharal2024predictivevalueof pages 1-2)
Cognitive impairment Cognitive impairment; HP:0100543 Cognitive changes reported in all 5 patients in Sheikh 2024; cognitive or visual impairment in 2/5 on initial exam Often accompanies headache/progressive symptoms and contributes to disability (sheikh2024primarycnsvasculitis pages 1-2)
Gait abnormality Abnormality of gait; HP:0001288 1/5 in Sheikh 2024 presented with cognitive and gait abnormality Suggests subcortical or multifocal lesion burden (sheikh2024primarycnsvasculitis pages 1-2)
Visual impairment Visual impairment; HP:0000505 2/5 had cognitive or visual impairment on initial exam in Sheikh 2024 May occur with focal deficits or posterior circulation/optic pathway involvement (sheikh2024primarycnsvasculitis pages 1-2)
Stroke-like episodes / acute ischemic events Stroke; HP:0001297 78.7% (11/14) in D’Aniello 2024 imaging cohort presented with stroke-like episodes CNS vasculitis frequently presents as ischemic cerebrovascular syndrome (d’aniello2024thecontributionof pages 2-4)
Transient ischemic attack-like episodes Transient ischemic attack 7.1% (1/14) in D’Aniello 2024 imaging cohort Less common than stroke-like presentation in retrieved evidence (d’aniello2024thecontributionof pages 2-4)
Hemorrhagic lesions / intracranial hemorrhage / microhemorrhages Intracranial hemorrhage; HP:0002170 SWI hemorrhages in 96.4% (54/56) of biopsy-proven PCNSV; MRI in Sheikh 2024 showed hemorrhage among abnormalities Hemorrhagic burden, especially microhemorrhages on SWI, is a notable imaging-associated phenotype in biopsy-proven disease (agarwal2024theroleof pages 11-12, sheikh2024primarycnsvasculitis pages 1-2)
White matter lesions Abnormal cerebral white matter morphology Most MRI lesions in biopsy-proven PCNSV were bilateral diffuse discrete-to-confluent white matter lesions Frequent radiologic phenotype; frontal lobe predominance reported (agarwal2024theroleof pages 2-3, agarwal2024theroleof pages 11-12)
Vasogenic edema Cerebral edema; HP:0002185 Reported among MRI abnormalities in Sheikh 2024; edema present in 87% of tumor-like PACNS cases reviewed in 2025 systematic review Important radiologic manifestation that can mimic tumor/inflammatory lesions (sheikh2024primarycnsvasculitis pages 1-2)
Restricted diffusion / acute ischemic injury Abnormality of brain imaging DWI abnormalities corresponded to vessel-wall enhancement in 77% of CNS vasculitis patients on VW-MRI study Suggests active ischemic injury in territories of inflamed vessels (d’aniello2024thecontributionof pages 1-2)
Contrast-enhancing brain lesions Abnormal CNS imaging with contrast enhancement Parenchymal enhancement in 96.3% (52/54) of biopsy-proven PCNSV; dot-linear pattern 87%, nodular 61.1%, perivascular 25.9%, patchy 16.7% Strongly supportive MRI pattern in biopsy-proven disease, though not disease-specific (agarwal2024theroleof pages 11-12)
Pseudotumoral / tumor-like mass lesions Abnormality of CNS imaging 45% of PACNS vs 10% of secondary CNS vasculitis in 2025 cohort; tumor-like PACNS recognized as a rare subtype in 2024 review Important mimic of glioma/lymphoma; often requires biopsy for diagnosis (scoppettuolo2025comparisonbetweenprimary pages 1-2)
Spinal cord involvement Abnormality of the spinal cord 15.8% in non-ABRA sv-PCNSV; spinal MRI involvement in 38.3% (12/33) in biopsy-proven PCNSV imaging series Indicates disease is not always confined to brain parenchyma alone (agarwal2024theroleof pages 11-12)
CSF pleocytosis Cerebrospinal fluid pleocytosis; HP:0003565 In PACNS vs ICAD, each +1 CSF WBC/µL increased odds of PACNS by 47% (OR 1.47, 95% CI 1.04–2.07); however, 17.4% of sv-PCNSV patients had normal CSF CSF inflammation supports diagnosis but normal CSF does not exclude disease (kharal2024predictivevalueof pages 1-2, d’aniello2024thecontributionof pages 15-16)
Low CSF glucose Decreased cerebrospinal fluid glucose concentration More common in secondary CNS vasculitis: 41.2% vs 8.7% in primary disease Helps suggest secondary, especially infectious, etiologies rather than PACNS (hoshina2024vasculitisinthe pages 2-3)
CSF oligoclonal bands Oligoclonal bands in CSF 63.6% in secondary CNS vasculitis vs 0 in primary disease in Hoshina 2024 May help differentiate secondary CNS vasculitis from PACNS in the right context (hoshina2024vasculitisinthe pages 2-3)
Fever / systemic inflammatory symptoms Fever; HP:0001945 26.3% in secondary CNS vasculitis vs 0% in primary CNS vasculitis Systemic features are uncommon in PACNS and may point toward secondary causes (hoshina2024vasculitisinthe pages 2-3, sheikh2024primarycnsvasculitis pages 1-2)
Need for walking aid / ambulatory disability Gait disturbance / impaired mobility In Sheikh 2024, all but one patient required walking aids initially; after treatment, 2 still required ambulatory aids Illustrates quality-of-life and disability burden from neurologic deficits (sheikh2024primarycnsvasculitis pages 1-2)

Table: This table summarizes reported clinical phenotypes and suggested HPO mappings for CNS vasculitis/PACNS, emphasizing frequencies and distinguishing features from recent cohorts and imaging studies. It is useful for knowledge-base phenotype annotation and for separating primary from secondary CNS vasculitis.

4. Genetic / Molecular Information

4.1 Causal genes / pathogenic variants

No PACNS/PCNSV causal genes or pathogenic variants were explicitly reported in the retrieved 2023–2024 core sources.

4.2 Molecular/histologic signatures (cellular composition)

In pediatric small-vessel CNS vasculitis biopsy material, immune infiltrates included CD3, CD4, CD8, and CD20 cells as predominant components (T-cell and B-cell rich angiocentric inflammation). (d’aniello2024thecontributionof pages 2-4)

5. Environmental Information

Not systematically addressed in retrieved 2023–2024 sources; secondary/infectious etiologies are recognized as major environmental/exogenous contributors in “secondary CNS vasculitis” categories. (hoshina2024vasculitisinthe pages 2-3)

6. Mechanism / Pathophysiology

6.1 Current understanding (causal chain)

A consistent mechanistic model across guideline/cohort/imaging evidence is: 1. Immune-mediated inflammation targets CNS vessel walls (small, medium, and/or large vessels), often with transmural involvement (histopathology emphasized in the ESO guideline). (pascarella2023europeanstrokeorganisation pages 1-2) 2. Vessel wall inflammation leads to luminal compromise, endothelial activation, and thrombosis/occlusion, producing ischemic injury; small-vessel fragility and inflammation also contribute to microhemorrhages detectable on SWI. (sheikh2024primarycnsvasculitis pages 1-2, agarwal2024theroleof pages 11-12) 3. Parenchymal injury manifests as multifocal neurologic deficits (headache/encephalopathy/focal deficits/seizures) and MRI abnormalities (white-matter lesions, diffusion restriction, enhancement). (hoshina2024vasculitisinthe pages 2-3, sheikh2024primarycnsvasculitis pages 1-2, d’aniello2024thecontributionof pages 1-2)

6.2 Histopathologic patterns

In a recent CNS vasculitis cohort, histologic phenotypes included lymphocytic, granulomatous, and necrotizing patterns. (hoshina2024vasculitisinthe pages 2-3)

6.3 Pathophysiology-related imaging biomarkers (2024)

  • Vessel-wall MRI: CNS vasculitis frequently shows intense, concentric vessel-wall enhancement (13/14 had enhancement; 84.6% intense; 92.3% concentric). (d’aniello2024thecontributionof pages 1-2)
  • DWI correlation: DWI alterations corresponded with vessel-wall enhancement territories in 77%, consistent with ischemic/hypoperfusion injury downstream of inflamed vessels. (d’aniello2024thecontributionof pages 1-2)
  • SWI microhemorrhages: extremely common in biopsy-proven PCNSV (96.4%). (agarwal2024theroleof pages 11-12)

6.4 Suggested ontology terms (examples)

Because formal ontology IDs were not provided in the sources, the following are suggested (not evidence-derived IDs): - GO biological processes (suggested): leukocyte migration; T cell activation; B cell activation; cytokine-mediated signaling; vasculature development/inflammation; endothelial cell activation. - CL cell types (suggested): T cell; CD4-positive T cell; CD8-positive T cell; B cell; endothelial cell.

7. Anatomical Structures Affected

7.1 Organ/system level

Primary disease is confined to the central nervous system: vessels of the brain, spinal cord, and meninges/leptomeninges. (sheikh2024primarycnsvasculitis pages 1-2, d’aniello2024thecontributionof pages 2-4)

7.2 Localization patterns (imaging)

  • Vessel-wall MRI cohort: enhancement affected the anterior circulation in 69.2% of patients and posterior circulation in 15.4%. (d’aniello2024thecontributionof pages 1-2)
  • Biopsy-proven PCNSV imaging series: frontal lobe lesions predominated; inferior cerebellar lesions were also frequent; lesions often bilateral and diffuse within white matter. (agarwal2024theroleof pages 11-12)

8. Temporal Development

8.1 Onset and diagnostic delay

PACNS/PCNSV can have subacute-to-chronic evolution and diagnostic delay. In a 2024 PCNSV series, symptoms persisted a median 36 weeks before diagnosis (range 3 weeks to 4 years). (sheikh2024primarycnsvasculitis pages 1-2)

8.2 Course patterns

Relapsing disease is recognized; in a biopsy-confirmed small-vessel PCNSV cohort, overall relapse rate was 19% (2025 evidence, included here due to limited relapse statistics in 2023–2024 sources). (kharal2024predictivevalueof pages 1-2)

9. Inheritance and Population

9.1 Epidemiology

Quantitative incidence was not systematically reported in the 2023 ESO guideline abstract, but a recent cohort-comparison paper cites an estimated incidence of ~2.4 cases per million person-years for PACNS (not a 2023–2024 primary epidemiology study; included as a commonly-cited estimate). (scoppettuolo2025comparisonbetweenprimary pages 1-2)

A 2024 single-center cohort provides internal proportions of primary vs secondary etiologies but is not population-based. (hoshina2024vasculitisinthe pages 2-3)

9.2 Demographics

  • Utah cohort: median age 54; 25% male overall. (hoshina2024vasculitisinthe pages 2-3)
  • PCNSV series (n=5): median onset age 31; 80% male (small series; likely not generalizable). (sheikh2024primarycnsvasculitis pages 1-2)

No genetic inheritance pattern is established for PACNS in the retrieved evidence.

10. Diagnostics

10.1 Diagnostic criteria / expert guidance

ESO 2023 key expert statements (abstract-level): - Overall evidence quality is very low across many diagnostic/treatment questions. - CSF pleocytosis/hyperproteinorrachia lack evidence as diagnostic tools. - Non-invasive vascular imaging must be interpreted with caution (lack of validation vs DSA/histopathology). - No neuroimaging pattern is specific for PACNS. - Multidisciplinary expert-center approach is recommended. (pascarella2023europeanstrokeorganisation pages 1-2)

10.2 Imaging advances and diagnostic performance signals (2024)

Key 2024 developments emphasize high-resolution vessel-wall MRI and advanced MRI signatures: - HR vessel-wall MRI frequently shows intense, concentric enhancement, supporting inflammatory vasculopathy evaluation. (d’aniello2024thecontributionof pages 1-2) - In biopsy-proven PCNSV, SWI microhemorrhages and dot-linear enhancement patterns were proposed as minor diagnostic criteria in a large single-center series (56 biopsy-positive). (agarwal2024theroleof pages 11-12) - Quantitative VWMRI metrics combined with clinical syndrome and CSF WBC can help discriminate PACNS from intracranial atherosclerotic disease: e.g., C/E ratio >1 (OR 115), concentricity ≥50% (OR 55), irregularity <50% (OR 55), seizure (OR 23), encephalopathy (OR 7.6). (kharal2024predictivevalueof pages 1-2)

10.3 Biopsy yield in real-world cohorts

  • Utah cohort: biopsy confirmed vasculitis in 7/10 biopsied PACNS cases and 4/4 inflammatory CAA cases. (hoshina2024vasculitisinthe pages 2-3)
  • Biopsy-proven PCNSV imaging series: 80 biopsies performed, 56 positive (70%). (agarwal2024theroleof pages 11-12)

Diagnostic modalities table

Test/modality What it assesses Key findings (numbers/ORs/%) Interpretation/role Source (URL/date)
Cerebrospinal fluid (CSF) analysis Pleocytosis, protein elevation, hypoglycorrhachia, oligoclonal bands ESO guideline: hyperproteinorrachia and pleocytosis "do not have evidence supporting their use as diagnostic tools." In Utah cohort (n=44), secondary CNS vasculitis had more low CSF glucose (41.2% vs 8.7%, P=0.02) and unique OCBs (63.6% vs 0, P<0.01); normal CSF can occur. In Kharal 2024, each +1 CSF WBC/µL increased odds of PACNS vs ICAD by 47% (OR 1.47, 95% CI 1.04–2.07). (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 2-3, kharal2024predictivevalueof pages 1-2) Supportive but nonspecific; useful for differential diagnosis and, with imaging/clinical context, may increase suspicion for PACNS, but cannot confirm or exclude it alone. ESO guideline: https://doi.org/10.1177/23969873231190431 (Oct 2023); Hoshina et al.: https://doi.org/10.1177/19418744231223283 (Dec 2024); Kharal et al.: https://doi.org/10.1212/cpj.0000000000200321 (Aug 2024)
Conventional brain MRI Parenchymal injury patterns: infarcts, hemorrhage, white-matter lesions, enhancement, edema ESO guideline: no neuroimaging pattern is specific for PACNS. Utah cohort: MRI abnormal in all cases (100%). D’Aniello 2024: DWI abnormalities matched vessel-wall enhancement territories in 77%. Agarwal 2024 biopsy-proven PCNSV series (n=56): parenchymal enhancement in 96.3% (52/54). (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 2-3, d’aniello2024thecontributionof pages 1-2, agarwal2024theroleof pages 11-12) Core first-line test to detect CNS injury and guide biopsy/imaging correlation, but findings are not pathognomonic. ESO guideline: https://doi.org/10.1177/23969873231190431 (Oct 2023); Hoshina et al.: https://doi.org/10.1177/19418744231223283 (Dec 2024); D’Aniello et al.: https://doi.org/10.3390/diagnostics14090927 (Apr 2024); Agarwal et al.: https://doi.org/10.1038/s41598-024-55222-2 (Feb 2024)
Diffusion-weighted imaging (DWI) Acute/subacute ischemic injury and lesion-territory correlation D’Aniello 2024: DWI alterations corresponded to vessel-wall enhancement in 77% of patients. (d’aniello2024thecontributionof pages 1-2) May reflect downstream ischemia/hypoperfusion or microembolization in territories of inflamed vessels; useful adjunct to vessel-wall imaging. https://doi.org/10.3390/diagnostics14090927 (Apr 2024)
Digital subtraction angiography (DSA) / vascular imaging Vessel caliber abnormalities, beading, stenosis/occlusion; medium/large-vessel disease ESO guideline: non-invasive vascular imaging should be interpreted cautiously because of limited validation and different sensitivities vs DSA/histopathology. Utah cohort: vasculitic changes on vessel imaging in 33/44 (75%); 12 showed large–middle vessel and 21 middle–small vessel patterns. Agarwal 2024: venous-phase pseudophlebitic abnormalities/venulitis in 95%, but few arterial stenoses/occlusions in biopsy-proven small-vessel PCNSV. (pascarella2023europeanstrokeorganisation pages 1-2, hoshina2024vasculitisinthe pages 2-3, agarwal2024theroleof pages 11-12) Helpful particularly for larger-vessel PACNS, but sensitivity is limited for small-vessel disease; a negative study does not exclude PACNS. ESO guideline: https://doi.org/10.1177/23969873231190431 (Oct 2023); Hoshina et al.: https://doi.org/10.1177/19418744231223283 (Dec 2024); Agarwal et al.: https://doi.org/10.1038/s41598-024-55222-2 (Feb 2024)
High-resolution vessel-wall MRI (VW-MRI/VWI) Arterial wall thickening and enhancement pattern (concentric vs eccentric; intense vs mild; vessel distribution) D’Aniello 2024 (n=14): enhancement in 13/14; intense in 84.6%; concentric in 92.3%; anterior circulation in 69.2%, posterior 15.4%, both 15.4%; middle cerebral artery involved in 69.2%. Kharal 2024: C/E ratio >1 (OR 115.00), concentricity ≥50% (OR 55.00), irregularity <50% (OR 55.00) predicted PACNS vs ICAD. Authors note smooth, concentric, diffuse thickening/enhancement is typical, whereas eccentric/focal patterns suggest ICAD. (d’aniello2024thecontributionof pages 1-2, d’aniello2024thecontributionof pages 2-4, kharal2024predictivevalueof pages 1-2) Promising adjunct for differentiating inflammatory vasculopathy from atherosclerotic disease and for mapping affected territories; still not fully validated as a stand-alone diagnostic test. D’Aniello et al.: https://doi.org/10.3390/diagnostics14090927 (Apr 2024); Kharal et al.: https://doi.org/10.1212/cpj.0000000000200321 (Aug 2024)
Susceptibility-weighted imaging (SWI) / GRE Microhemorrhages, macrohemorrhages, hemorrhagic burden Agarwal 2024 biopsy-proven PCNSV series: SWI hemorrhages in 96.4% (54/56); SWI described as five times more sensitive than T2* for hemorrhage detection; microbleeds may persist despite steroid treatment. D’Aniello dataset also reported SWI microbleeds in some PCNSV patients. (agarwal2024theroleof pages 11-12, d’aniello2024thecontributionof pages 8-9) Particularly valuable in small-vessel PCNSV where microhemorrhages are common; may be a useful minor diagnostic clue in the right clinical setting. Agarwal et al.: https://doi.org/10.1038/s41598-024-55222-2 (Feb 2024); D’Aniello et al.: https://doi.org/10.3390/diagnostics14090927 (Apr 2024)
Contrast-enhanced T1-weighted MRI Parenchymal, perivascular, leptomeningeal, pachymeningeal enhancement Agarwal 2024: parenchymal enhancement in 96.3% (52/54); dot-linear pattern 87%, nodular 61.1%, perivascular 25.9%, patchy 16.7%; leptomeningeal enhancement 20.8%; pachymeningeal enhancement 7.6%. (agarwal2024theroleof pages 11-12) High-yield adjunct in biopsy-proven PCNSV; dot-linear/perivascular enhancement patterns may raise suspicion for PCNSV, especially with hemorrhagic SWI findings. https://doi.org/10.1038/s41598-024-55222-2 (Feb 2024)
Clinical + CSF + quantitative VWMRI model Composite diagnostic discrimination between PACNS and intracranial atherosclerotic disease (ICAD) Kharal 2024 (n=59): encephalopathy OR 7.60 (95% CI 1.07–54.09), seizure OR 23.00 (1.77–298.45), headache significant in sensitivity analysis; CSF WBC OR 1.47 per 1 cell/µL; VWMRI metrics had strongest associations (C/E ratio >1 OR 115.00; concentricity ≥50% OR 55.00; irregularity <50% OR 55.00). (kharal2024predictivevalueof pages 1-2) Suggests PACNS diagnosis is strengthened by integrating syndrome features, inflammatory CSF, and vessel-wall geometry rather than relying on a single test. https://doi.org/10.1212/cpj.0000000000200321 (Aug 2024)
Brain biopsy / histopathology Direct confirmation of vasculitis and subtype/pattern (lymphocytic, granulomatous, necrotizing; exclusion of mimics) ESO guideline and D’Aniello 2024: biopsy is the gold standard / required for definite PCNSV. D’Aniello notes biopsy can be nondiagnostic in up to 50% of cases. Hoshina 2024: PACNS biopsy positive in 7/10; inflammatory CAA 4/4. Agarwal 2024: 80 biopsies performed, 56/80 positive (70%) for PCNSV. (pascarella2023europeanstrokeorganisation pages 1-2, d’aniello2024thecontributionof pages 1-2, hoshina2024vasculitisinthe pages 2-3, agarwal2024theroleof pages 11-12) Reference standard for definite diagnosis, especially crucial in small-vessel disease and tumor-like or mimic-rich presentations; false negatives remain an important limitation. ESO guideline: https://doi.org/10.1177/23969873231190431 (Oct 2023); D’Aniello et al.: https://doi.org/10.3390/diagnostics14090927 (Apr 2024); Hoshina et al.: https://doi.org/10.1177/19418744231223283 (Dec 2024); Agarwal et al.: https://doi.org/10.1038/s41598-024-55222-2 (Feb 2024)

Table: This table summarizes the main 2023-2024 diagnostic tests used in CNS vasculitis/PACNS and the most relevant quantitative findings from recent guideline, cohort, and imaging studies. It is useful for comparing what each modality measures, how strongly it supports diagnosis, and where its limitations lie.

11. Outcome / Prognosis

11.1 Mortality

In a 2011–2022 CNS vasculitis single-center cohort (n=44), overall mortality was 20.5% (primary 16.0%, secondary 26.3%). (hoshina2024vasculitisinthe pages 2-3)

11.2 Functional outcomes

In the 2024 PCNSV series with median 56-month follow-up (n=5), outcomes varied: some improved, some remained stable, and one deteriorated; mobility aids remained necessary for some patients after treatment. (sheikh2024primarycnsvasculitis pages 1-2)

Robust long-term survival or disability statistics (5-year/10-year) were not available in the retrieved 2023–2024 evidence.

12. Treatment

12.1 Current standard practice (induction/maintenance)

Across guideline and contemporary clinical series, common treatment paradigms include: - Induction: high-dose corticosteroids, often with cyclophosphamide for severe disease. (sheikh2024primarycnsvasculitis pages 1-2, rice2026primarycentralnervous pages 2-4) - Maintenance / steroid-sparing: azathioprine, methotrexate, or mycophenolate mofetil; rituximab is used in some cohorts as maintenance or for refractory disease. (sheikh2024primarycnsvasculitis pages 1-2, hoshina2024vasculitisinthe pages 1-2, rice2026primarycentralnervous pages 2-4)

ESO 2023 perspective: treatment recommendations for induction and maintenance reflect substantial uncertainty because controlled trial evidence is sparse. (pascarella2023europeanstrokeorganisation pages 1-2)

12.2 Real-world implementation statistics

In the Utah cohort (n=44): - IV methylprednisolone was predominant induction therapy (63.6%). - Cyclophosphamide was the most used adjunctive therapy. - Maintenance therapy included cyclophosphamide, rituximab, azathioprine, and mycophenolate (often with prednisone). (hoshina2024vasculitisinthe pages 2-3, hoshina2024vasculitisinthe pages 1-2)

12.3 Suggested MAXO terms (examples)

Suggested (not source-derived IDs): systemic glucocorticoid therapy; cyclophosphamide therapy; B-cell depletion therapy (rituximab); immunosuppressive maintenance therapy; plasma exchange; brain biopsy; MRI; cerebral angiography.

Treatment summary table

Treatment/strategy Phase (induction/maintenance) Evidence type Key quantitative outcome Notes Source
Intravenous methylprednisolone Induction Single-center retrospective CNS vasculitis cohort (n=44) Used in 28/44 patients (63.6%); overall cohort mortality 9/44 (20.5%), primary 16.0%, secondary 26.3% Predominant induction therapy across CNS vasculitis etiologies; outcome figures are cohort-level, not steroid-specific (hoshina2024vasculitisinthe pages 2-3, hoshina2024vasculitisinthe pages 1-2) Hoshina 2024, Neurohospitalist, published Dec 2024, https://doi.org/10.1177/19418744231223283 (hoshina2024vasculitisinthe pages 2-3, hoshina2024vasculitisinthe pages 1-2)
High-dose corticosteroids ± cyclophosphamide Induction 2023 European guideline / expert consensus No pooled effect size established; evidence judged very low quality ESO guideline states induction recommendations reflect major uncertainty due to sparse evidence; management should be multidisciplinary in expert centers (pascarella2023europeanstrokeorganisation pages 1-2) Pascarella et al. 2023, European Stroke Journal, Oct 2023, https://doi.org/10.1177/23969873231190431 (pascarella2023europeanstrokeorganisation pages 1-2)
Corticosteroids plus cyclophosphamide Induction Single-center retrospective PCNSV series (n=5) / narrative clinical update No formal response rate reported; 2 improved, 2 stable, 1 deteriorated over median 56 months follow-up Authors describe prompt immunotherapy, typically corticosteroids plus cyclophosphamide, as recommended induction; report states immunotherapy significantly improved clinical and radiologic outcomes, but not with drug-specific percentages (sheikh2024primarycnsvasculitis pages 1-2) Sheikh et al. 2024, Frontiers in Neurology, Apr 2024, https://doi.org/10.3389/fneur.2024.1363985 (sheikh2024primarycnsvasculitis pages 1-2)
Cyclophosphamide as adjunct to steroids Induction / adjunct Single-center retrospective CNS vasculitis cohort (n=44) Most used adjunctive therapy; subgroup use reported as 47.1%, 25%, and 66.7% in cohort summaries Frequently paired with IV methylprednisolone in real-world practice; exact efficacy by subgroup not isolated in retrieved evidence (hoshina2024vasculitisinthe pages 2-3) Hoshina 2024, https://doi.org/10.1177/19418744231223283 (hoshina2024vasculitisinthe pages 2-3)
Intravenous cyclophosphamide Induction Comparative retrospective cohort, PACNS vs secondary CNS vasculitis (20 vs 20) Nearly half of PACNS patients received IV cyclophosphamide for induction; mortality/relapse/outcomes did not differ between PACNS and SACNS PACNS showed more seizures and pseudotumoral lesions, but outcome separation by induction regimen was not demonstrated (scoppettuolo2025comparisonbetweenprimary pages 11-12, scoppettuolo2025comparisonbetweenprimary pages 1-2) Scoppettuolo et al. 2025, Frontiers in Neurology, Oct 2025, https://doi.org/10.3389/fneur.2025.1602427 (scoppettuolo2025comparisonbetweenprimary pages 11-12, scoppettuolo2025comparisonbetweenprimary pages 1-2)
Cyclophosphamide within 3 months (“early intensive treatment”) Early intensive induction Retrospective biopsy-proven small-vessel PCNSV cohort (n=26; non-ABRA subgroup n=19) Remission in 12/12 (100%) early-intensive group vs 11/14 (78.6%) escalation group; median time to remission 5 vs 19 months; HR 0.24, 95% CI 0.10–0.63, p<0.005; overall relapse 19% Strongest quantitative treatment-outcome signal in retrieved evidence; supports earlier aggressive therapy in sv-PCNSV, though from 2025 source Reddy et al. 2025, Neurology Neuroimmunology & Neuroinflammation, Jul 2025, https://doi.org/10.1212/NXI.0000000000200397 (kharal2024predictivevalueof pages 1-2)
Glucocorticoids alone or with azathioprine/mycophenolate/methotrexate (“escalation treatment”) Initial non-intensive induction / early maintenance Retrospective biopsy-proven small-vessel PCNSV cohort Remission achieved in 11/14 (78.6%); slower median time to remission (19 months) than early cyclophosphamide group Comparator arm in Reddy 2025; suggests less rapid disease control than early intensive cyclophosphamide (kharal2024predictivevalueof pages 1-2) Reddy et al. 2025, https://doi.org/10.1212/NXI.0000000000200397 (kharal2024predictivevalueof pages 1-2)
Azathioprine Maintenance Cohort + review/expert opinion Used as maintenance in real-world cohort; in PACNS/SACNS comparison, azathioprine was the commonest maintenance agent; no regimen-specific remission rate reported Common steroid-sparing maintenance option after induction; often continued for at least 2 years in expert practice summaries (hoshina2024vasculitisinthe pages 1-2, scoppettuolo2025comparisonbetweenprimary pages 1-2) Hoshina 2024, https://doi.org/10.1177/19418744231223283; Scoppettuolo 2025, https://doi.org/10.3389/fneur.2025.1602427 (hoshina2024vasculitisinthe pages 1-2, scoppettuolo2025comparisonbetweenprimary pages 1-2)
Mycophenolate mofetil Maintenance Cohort + review/expert opinion Used in maintenance; no drug-specific response percentage reported in retrieved evidence Listed among maintenance/steroid-sparing agents after induction in PCNSV/PACNS (sheikh2024primarycnsvasculitis pages 1-2, hoshina2024vasculitisinthe pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2) Sheikh 2024, https://doi.org/10.3389/fneur.2024.1363985; Hoshina 2024, https://doi.org/10.1177/19418744231223283; Rice 2026, https://doi.org/10.1007/s00415-026-13727-y (sheikh2024primarycnsvasculitis pages 1-2, hoshina2024vasculitisinthe pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2)
Methotrexate Maintenance Review/expert opinion and clinical series No quantitative outcome reported in retrieved evidence Included among less toxic post-induction maintenance immunosuppressants (sheikh2024primarycnsvasculitis pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2) Sheikh 2024, https://doi.org/10.3389/fneur.2024.1363985; Rice 2026, https://doi.org/10.1007/s00415-026-13727-y; Scoppettuolo 2025, https://doi.org/10.3389/fneur.2025.1602427 (sheikh2024primarycnsvasculitis pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2)
Rituximab Maintenance / alternative immunomodulator Real-world cohort + review/expert opinion Used in maintenance cohorts; no PACNS-specific response rate quantified in retrieved evidence Considered a steroid-sparing or refractory-disease option; case-report/series evidence exists, but robust comparative data lacking (hoshina2024vasculitisinthe pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2) Hoshina 2024, https://doi.org/10.1177/19418744231223283; Rice 2026, https://doi.org/10.1007/s00415-026-13727-y; Scoppettuolo 2025, https://doi.org/10.3389/fneur.2025.1602427 (hoshina2024vasculitisinthe pages 1-2, rice2026primarycentralnervous pages 2-4, scoppettuolo2025comparisonbetweenprimary pages 1-2)
Prednisone with maintenance immunosuppressants Maintenance / taper Retrospective cohort Often used concurrently with cyclophosphamide, rituximab, azathioprine, or mycophenolate; no isolated efficacy estimate Reflects common real-world tapering strategy after IV steroid induction (hoshina2024vasculitisinthe pages 1-2) Hoshina 2024, https://doi.org/10.1177/19418744231223283 (hoshina2024vasculitisinthe pages 1-2)
Plasma exchange (PLEX) Adjunct / rescue Small cohort observation 2 PACNS cases received PLEX with favorable outcomes Evidence is anecdotal and insufficient for routine recommendation (hoshina2024vasculitisinthe pages 2-3) Hoshina 2024, https://doi.org/10.1177/19418744231223283 (hoshina2024vasculitisinthe pages 2-3)
Maintenance immunosuppression after remission Maintenance strategy Review/expert opinion No numeric estimate in retrieved excerpt; cited as improving long-term outcomes in prior literature referenced by review Rice 2026 notes maintenance with azathioprine, methotrexate, or mycophenolate after induction, extrapolated largely from systemic vasculitis evidence (rice2026primarycentralnervous pages 2-4) Rice & Scolding 2026, Journal of Neurology, Mar 2026, https://doi.org/10.1007/s00415-026-13727-y (rice2026primarycentralnervous pages 2-4)

Table: This table summarizes induction, maintenance, and adjunctive treatment strategies for CNS vasculitis/PACNS and the main quantitative outcomes available from the retrieved evidence. It is useful for distinguishing consensus-based practice from the few cohorts that report remission, relapse, and mortality statistics.

13. Prevention

No primary prevention strategy is established for PACNS/PCNSV in the retrieved evidence; prevention is largely secondary/tertiary, focused on early recognition, exclusion of mimics/secondary causes, and relapse prevention with maintenance immunosuppression (expert practice). (pascarella2023europeanstrokeorganisation pages 1-2, rice2026primarycentralnervous pages 2-4)

14. Other Species / Natural Disease

No animal/natural disease information was identified in the retrieved sources.

15. Model Organisms

No model organism systems were described in the retrieved sources.

Recent developments (2023–2024 highlights)

  1. First comprehensive European PACNS guideline using GRADE (Oct 2023): emphasizes very low evidence quality, non-specific MRI patterns, and the need for expert-center multidisciplinary care and standardized neuroimaging/reporting. (pascarella2023europeanstrokeorganisation pages 1-2)
  2. Rapid growth in vessel-wall MRI evidence (Apr 2024): intense, concentric enhancement frequently observed in CNS vasculitis, supporting VWI as an adjunct to conventional MRI/MRA/DSA. (d’aniello2024thecontributionof pages 1-2)
  3. Advanced MRI signatures in biopsy-proven PCNSV (Feb 2024): near-universal SWI hemorrhages and high rates of contrast enhancement with characteristic patterns; proposal to incorporate SWI hemorrhage and dot-linear enhancement as minor diagnostic criteria. (agarwal2024theroleof pages 11-12)
  4. Quantitative VWMRI + CSF/clinical predictors (Aug 2024): strong ORs for VWMRI geometry metrics and clinical syndromes distinguishing PACNS from intracranial atherosclerosis in a stroke/vasculopathy cohort. (kharal2024predictivevalueof pages 1-2)

Clinical trials and translational pipeline (real-world implementations)

  • NCT03166319 (Mayo Clinic; completed; start 2017-07-24, completion 2020-11-24): pilot interventional diagnostic study of intracranial HR vessel-wall MRI for suspected PACNS; enrollment 15; repeated MRI/MRA/VWI with gadolinium; imaging read by two neuroradiologists. URL: https://clinicaltrials.gov/study/NCT03166319 (NCT03166319 chunk 1)
  • NCT05168475 BIOVAS (Cambridge University Hospitals NHS Foundation Trust; Phase 2; terminated due to funding withdrawal): randomized double-blind placebo-controlled modified-crossover trial planning sequential exposure to infliximab, rituximab, tocilizumab and placebo in refractory primary non-ANCA-associated vasculitis including PACNS; enrollment 22; primary endpoint treatment failure up to 720 days defined via BVAS/PVAS modifications. URL: https://clinicaltrials.gov/study/NCT05168475 (NCT05168475 chunk 1)
  • NCT00659776 (OHSU; Phase 2; terminated): ferumoxytol MRI for CNS inflammation/vascular processes; enrollment 255; diagnostic imaging endpoints and histologic/EM correlation. URL: https://clinicaltrials.gov/study/NCT00659776 (NCT00659776 chunk 1)

Evidence limitations and gaps (explicit)

  • Ontology identifiers (MONDO/MeSH/Orphanet/OMIM/ICD-11) were not present in the retrieved evidence; they should be added by direct ontology lookup in dedicated resources (e.g., MONDO/Orphanet/MeSH browsers) rather than inferred. (hoshina2024vasculitisinthe pages 2-3)
  • Many “classic” PACNS statements rely on older cohorts and expert consensus; the ESO guideline explicitly characterizes the evidence base as very low quality for many clinical questions, reinforcing that 2023–2024 advances are primarily in imaging characterization rather than randomized treatment trials. (pascarella2023europeanstrokeorganisation pages 1-2)
  • PMIDs were not provided in the retrieved full-text evidence snippets; the report therefore cites DOI/URLs and journal metadata from the retrieved sources.

Key cited sources (2023–2024 prioritized)

  • Pascarella R, et al. European Stroke Organisation (ESO) guidelines on PACNS. European Stroke Journal. Oct 2023. https://doi.org/10.1177/23969873231190431 (pascarella2023europeanstrokeorganisation pages 1-2)
  • D’Aniello S, et al. Vessel wall MRI in primary/secondary CNS vasculitis. Diagnostics. Apr 2024. https://doi.org/10.3390/diagnostics14090927 (d’aniello2024thecontributionof pages 1-2)
  • Agarwal S, et al. SWI and contrast MRI in biopsy-proven PCNSV (case series). Scientific Reports. Feb 2024. https://doi.org/10.1038/s41598-024-55222-2 (agarwal2024theroleof pages 11-12)
  • Kharal MMGA, et al. Clinical/CSF/VWMRI predictors of PACNS vs ICAD. Neurology Clinical Practice. Aug 2024. https://doi.org/10.1212/cpj.0000000000200321 (kharal2024predictivevalueof pages 1-2)
  • Hoshina Y, et al. Etiology and outcomes in CNS vasculitis cohort (n=44). The Neurohospitalist. Dec 2024. https://doi.org/10.1177/19418744231223283 (hoshina2024vasculitisinthe pages 2-3)
  • Sheikh TS, et al. Clinical/neuropath/radiologic characteristics of PCNSV (series). Frontiers in Neurology. Apr 2024. https://doi.org/10.3389/fneur.2024.1363985 (sheikh2024primarycnsvasculitis pages 1-2)

References

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  2. (hoshina2024vasculitisinthe pages 2-3): Yoji Hoshina, Alen Delic, Ka-Ho Wong, Stephanie Lyden, Robert Kadish, Tammy L. Smith, Melissa A. Wright, Daisuke Shimura, and Stacey L. Clardy. Vasculitis in the central nervous system: etiology, characteristics, and outcomes in a large single-center cohort. The Neurohospitalist, 14:129-139, Dec 2024. URL: https://doi.org/10.1177/19418744231223283, doi:10.1177/19418744231223283. This article has 6 citations.

  3. (sheikh2024primarycnsvasculitis pages 1-2): Tahani Saker Sheikh, Ayal Rozenberg, Goni Merhav, Alla Shifrin, Polina Stein, and Shahar Shelly. Primary cns vasculitis: insights into clinical, neuropathological, and neuroradiological characteristics. Frontiers in Neurology, Apr 2024. URL: https://doi.org/10.3389/fneur.2024.1363985, doi:10.3389/fneur.2024.1363985. This article has 6 citations and is from a peer-reviewed journal.

  4. (hoshina2024vasculitisinthe pages 1-2): Yoji Hoshina, Alen Delic, Ka-Ho Wong, Stephanie Lyden, Robert Kadish, Tammy L. Smith, Melissa A. Wright, Daisuke Shimura, and Stacey L. Clardy. Vasculitis in the central nervous system: etiology, characteristics, and outcomes in a large single-center cohort. The Neurohospitalist, 14:129-139, Dec 2024. URL: https://doi.org/10.1177/19418744231223283, doi:10.1177/19418744231223283. This article has 6 citations.

  5. (d’aniello2024thecontributionof pages 1-2): Serena D’Aniello, Arianna Rustici, Laura Ludovica Gramegna, Claudia Godi, Laura Piccolo, Mauro Gentile, Andrea Zini, Alessandro Carrozzi, Raffaele Lodi, Caterina Tonon, Massimo Dall’Olio, Luigi Simonetti, Raffaella Chieffo, Nicoletta Anzalone, and Luigi Cirillo. The contribution of vessel wall magnetic resonance imaging to the diagnosis of primary and secondary central nervous system vasculitis. Diagnostics, 14:927, Apr 2024. URL: https://doi.org/10.3390/diagnostics14090927, doi:10.3390/diagnostics14090927. This article has 12 citations.

  6. (agarwal2024theroleof pages 11-12): Sushant Agarwal, Leve Joseph Devarajan Sebastian, Shailesh Gaikwad, M. V. Padma Srivastava, M. C. Sharma, Manmohan Singh, Rohit Bhatia, Ayush Agarwal, Jyoti Sharma, Deepa Dash, Vinay Goyal, Achal K. Srivastava, Manjari Tripathi, Vaishali Suri, Mamta B. Singh, Chitra Sarkar, Ashish Suri, Rajesh K. Singh, Deepti Vibha, Awadh K. Pandit, Roopa Rajan, Anu Gupta, A. Elavarasi, Divya M. Radhakrishnan, Animesh Das, Vivek Tandon, Ramesh Doddamani, Ashish Upadhyay, Venugopalan Y. Vishnu, and Ajay Garg. The role of susceptibility-weighted imaging & contrast-enhanced mri in the diagnosis of primary cns vasculitis: a large case series. Scientific Reports, Feb 2024. URL: https://doi.org/10.1038/s41598-024-55222-2, doi:10.1038/s41598-024-55222-2. This article has 13 citations and is from a peer-reviewed journal.

  7. (scoppettuolo2025comparisonbetweenprimary pages 1-2): Pasquale Scoppettuolo, Lucie Pothen, Aline van Maanen, Valeria Onofrj, Selda Aydin, Olivier Gheysens, Renaud Lhommel, André Peeters, Vincent van Pesch, and Halil Yildiz. Comparison between primary and secondary central nervous system vasculitis in terms of clinical, biochemical, radiological, histopathological features, and outcomes: a single-center retrospective cohort study. Frontiers in Neurology, Oct 2025. URL: https://doi.org/10.3389/fneur.2025.1602427, doi:10.3389/fneur.2025.1602427. This article has 1 citations and is from a peer-reviewed journal.

  8. (d’aniello2024thecontributionof pages 2-4): Serena D’Aniello, Arianna Rustici, Laura Ludovica Gramegna, Claudia Godi, Laura Piccolo, Mauro Gentile, Andrea Zini, Alessandro Carrozzi, Raffaele Lodi, Caterina Tonon, Massimo Dall’Olio, Luigi Simonetti, Raffaella Chieffo, Nicoletta Anzalone, and Luigi Cirillo. The contribution of vessel wall magnetic resonance imaging to the diagnosis of primary and secondary central nervous system vasculitis. Diagnostics, 14:927, Apr 2024. URL: https://doi.org/10.3390/diagnostics14090927, doi:10.3390/diagnostics14090927. This article has 12 citations.

  9. (kharal2024predictivevalueof pages 1-2): M. M. G. Abbas Kharal, MD Sidonie E. Ibrikji, MD Youssef M. Farag, Aaron Shoskes PhD, P. DOMatthew, DO Richa Kiczek, MD Muhammad S Sheth, and MD Hussain. Predictive value of clinical, csf and vessel wall mri variables in diagnosing primary angiitis of the cns. Neurology Clinical Practice, Aug 2024. URL: https://doi.org/10.1212/cpj.0000000000200321, doi:10.1212/cpj.0000000000200321. This article has 5 citations.

  10. (agarwal2024theroleof pages 2-3): Sushant Agarwal, Leve Joseph Devarajan Sebastian, Shailesh Gaikwad, M. V. Padma Srivastava, M. C. Sharma, Manmohan Singh, Rohit Bhatia, Ayush Agarwal, Jyoti Sharma, Deepa Dash, Vinay Goyal, Achal K. Srivastava, Manjari Tripathi, Vaishali Suri, Mamta B. Singh, Chitra Sarkar, Ashish Suri, Rajesh K. Singh, Deepti Vibha, Awadh K. Pandit, Roopa Rajan, Anu Gupta, A. Elavarasi, Divya M. Radhakrishnan, Animesh Das, Vivek Tandon, Ramesh Doddamani, Ashish Upadhyay, Venugopalan Y. Vishnu, and Ajay Garg. The role of susceptibility-weighted imaging & contrast-enhanced mri in the diagnosis of primary cns vasculitis: a large case series. Scientific Reports, Feb 2024. URL: https://doi.org/10.1038/s41598-024-55222-2, doi:10.1038/s41598-024-55222-2. This article has 13 citations and is from a peer-reviewed journal.

  11. (d’aniello2024thecontributionof pages 15-16): Serena D’Aniello, Arianna Rustici, Laura Ludovica Gramegna, Claudia Godi, Laura Piccolo, Mauro Gentile, Andrea Zini, Alessandro Carrozzi, Raffaele Lodi, Caterina Tonon, Massimo Dall’Olio, Luigi Simonetti, Raffaella Chieffo, Nicoletta Anzalone, and Luigi Cirillo. The contribution of vessel wall magnetic resonance imaging to the diagnosis of primary and secondary central nervous system vasculitis. Diagnostics, 14:927, Apr 2024. URL: https://doi.org/10.3390/diagnostics14090927, doi:10.3390/diagnostics14090927. This article has 12 citations.

  12. (d’aniello2024thecontributionof pages 8-9): Serena D’Aniello, Arianna Rustici, Laura Ludovica Gramegna, Claudia Godi, Laura Piccolo, Mauro Gentile, Andrea Zini, Alessandro Carrozzi, Raffaele Lodi, Caterina Tonon, Massimo Dall’Olio, Luigi Simonetti, Raffaella Chieffo, Nicoletta Anzalone, and Luigi Cirillo. The contribution of vessel wall magnetic resonance imaging to the diagnosis of primary and secondary central nervous system vasculitis. Diagnostics, 14:927, Apr 2024. URL: https://doi.org/10.3390/diagnostics14090927, doi:10.3390/diagnostics14090927. This article has 12 citations.

  13. (rice2026primarycentralnervous pages 2-4): Claire Rice and Neil Scolding. Primary central nervous system vasculitis: an update. Journal of Neurology, Mar 2026. URL: https://doi.org/10.1007/s00415-026-13727-y, doi:10.1007/s00415-026-13727-y. This article has 0 citations and is from a domain leading peer-reviewed journal.

  14. (scoppettuolo2025comparisonbetweenprimary pages 11-12): Pasquale Scoppettuolo, Lucie Pothen, Aline van Maanen, Valeria Onofrj, Selda Aydin, Olivier Gheysens, Renaud Lhommel, André Peeters, Vincent van Pesch, and Halil Yildiz. Comparison between primary and secondary central nervous system vasculitis in terms of clinical, biochemical, radiological, histopathological features, and outcomes: a single-center retrospective cohort study. Frontiers in Neurology, Oct 2025. URL: https://doi.org/10.3389/fneur.2025.1602427, doi:10.3389/fneur.2025.1602427. This article has 1 citations and is from a peer-reviewed journal.

  15. (NCT03166319 chunk 1): Vance Lehman. Vessel Wall Imaging for Diagnosis and Monitoring of Central Nervous System (CNS) Vasculitis. Mayo Clinic. 2017. ClinicalTrials.gov Identifier: NCT03166319

  16. (NCT05168475 chunk 1): David Jayne. Biologics in Refractory Vasculitis: A Trial of Biologic Therapy for Refractory Primary Non-ANCA Associated Vasculitis. Cambridge University Hospitals NHS Foundation Trust. 2021. ClinicalTrials.gov Identifier: NCT05168475

  17. (NCT00659776 chunk 1): Edward Neuwelt. MR, Histologic And EM Imaging Of Intravenous Ferumoxytol In Central Nervous System (CNS) Inflammation. Oregon Health and Science University. 2004. ClinicalTrials.gov Identifier: NCT00659776

Artifacts

OpenScientist ▸
1. Disease Information
openscientist-autonomous 56 citations 2026-05-16T04:06:00.037920

1. Disease Information

Overview

CNS Vasculitis encompasses inflammatory disorders affecting blood vessels of the central nervous system. PACNS is the primary (idiopathic) form, restricted exclusively to the brain, spinal cord, and leptomeninges without systemic involvement. Secondary CNS vasculitis occurs as a manifestation of systemic diseases including ANCA-associated vasculitides, Behcet's disease, systemic lupus erythematosus, sarcoidosis, and infections.

PACNS was first described by Cravioto and Feigin in 1959 and later defined by Calabrese and Mallek in 1988 with three criteria: (1) an acquired neurological deficit unexplained by other diagnoses, (2) angiographic or histopathologic evidence of CNS vasculitis, and (3) no evidence of systemic vasculitis or infection. It remains "a rare autoimmune condition characterized by exclusive involvement of the brain, spinal cord, and leptomeninges" with "an estimated prevalence of 2.4 cases per million person-years in North America" representing "one of the rarest vasculitides" (PMID: 41947889).

Key Identifiers

Identifier Code/Term
ICD-10 I67.7 (Cerebral arteritis, not elsewhere classified)
ICD-11 8B22.0 (Primary angiitis of the central nervous system)
MeSH D020293 (Vasculitis, Central Nervous System)
MONDO MONDO:0007141 (cerebral vasculitis)
Orphanet ORPHA:140989 (Primary angiitis of the central nervous system)
DOID DOID:13550 (central nervous system vasculitis)
SNOMED CT 195185003 (Cerebral arteritis)
OMIM Not assigned for PACNS (DADA2: 615688)

Synonyms and Alternative Names

  • Primary angiitis of the central nervous system (PACNS)
  • Primary central nervous system vasculitis (PCNSV)
  • Isolated angiitis of the CNS
  • Granulomatous angiitis of the CNS (historical)
  • Cerebral vasculitis (primary)

Information Sources

This report is derived from aggregated disease-level resources including systematic reviews, multicenter cohort studies, meta-analyses, and case series. Key data sources include the largest systematic review and meta-analysis of 46 cohort studies encompassing 911 PACNS patients (PMID: 34663675), a multicenter German cohort of 163 patients (PMID: 40546217), and multiple single-center biopsy-proven cohorts. Information is synthesized from 113 scientific publications with 40+ unique PMID citations.

2. Etiology

Disease Causal Factors

PACNS is of unknown etiology. It is classified as an autoimmune/autoinflammatory condition, but the precise triggers remain elusive. The disease likely involves a combination of:

  • Immune dysregulation: Aberrant activation of innate and adaptive immune responses targeting cerebral vessel walls, with dendritic cell maturation, NK cell activation, M1 macrophage polarization, and elevated IL-17 in CSF (PMID: 41947889; PMID: 36264136)
  • Infectious triggers: Varicella zoster virus (VZV) has been identified as a potential trigger — anti-VZV IgG antibodies were detected in CSF of 32% of primary cerebral vasculitis patients, suggesting VZV activation in the trigeminal ganglion with transaxonal spread to cerebral arteries (PMID: 41782529). VZV reactivation was found in 37% of HIV-infected and 9% of HIV-uninfected young adults presenting with stroke (PMID: 35133008)
  • Amyloid-related mechanisms: In the ABRA subtype, inflammatory response directed against vascular amyloid-beta accumulation (PMID: 37151140)
  • Genetic susceptibility: While no GWAS has been performed for PACNS specifically due to its rarity, cross-vasculitis genetics implicate HLA region polymorphisms as major susceptibility factors

Risk Factors

Genetic Risk Factors

No PACNS-specific causal genes have been identified through GWAS. However, cross-phenotype Immunochip meta-analysis of 2,465 vasculitis patients identified shared susceptibility loci across vasculitides, with the HLA region showing the strongest signals (PMID: 29374629). Related vasculitis genetics include:

  • HLA-B*52: Associated with Takayasu arteritis (OR=3.29, p=5.57×10⁻¹⁶) (PMID: 23830517)
  • HLA-B*51: Strongest genetic association with Behcet's disease (which causes secondary CNS vasculitis)
  • ApoE ε4/ε4 genotype: Found in up to 70% of ABRA patients, strongly linking this PACNS subtype to cerebral amyloid angiopathy (PMID: 24636849)
  • ERAP1, CCR1-CCR3, STAT4, KLRC4, GIMAP4, TNFAIP3: Associated with Behcet's disease; SERPINA1 and SEMA6A: Associated with ANCA-associated vasculitides (PMID: 25405820)
  • ADA2 gene mutations: Biallelic mutations cause DADA2, a monogenic CNS vasculitis mimic (OMIM: 615688)
  • TBC1D3C and TBC1D3L gene upregulation: Identified in PACNS brain tissue, suggesting altered vesicular trafficking (PMID: 41947889)

Environmental Risk Factors

  • Infections: VZV, HIV, CMV, tuberculosis, syphilis, and other neurotropic pathogens can trigger secondary or post-infectious CNS vasculitis (PMID: 39663273)
  • Age: PACNS median age of onset 46–48 years; older age associated with poorer survival (HR 1.96 per 10 years) (PMID: 40546217); pediatric forms have mean onset of ~7.89 years
  • Sex: Slight male predominance in most adult cohorts (55–58% male), though some series report near-equal distribution (45% female in the German cohort)
  • Cardiovascular risk factors: Body weight has been specifically associated with PACNS vessel-size phenotype (PMID: 41041677)
  • Adverse childhood experiences (ACEs): Associated with neuropsychiatric SLE (adjusted OR=3.40, 95% CI 1.55–7.78), suggesting psychosocial stress may contribute to secondary CNS vasculitis (PMID: 42009372)

Protective Factors

  • HLA-C*03: Identified as a putative protective factor in Takayasu arteritis, present exclusively in patients with clinically mild disease (PMID: 34931621)
  • HLA-B*44: Under-transmitted in Kawasaki disease families, suggesting a protective role (PMID: 25809546)
  • Early diagnosis and treatment: Strongest modifiable factor; longer time from onset to treatment is an independent predictor of worse outcomes (PMID: 41479923)
  • No PACNS-specific protective factors have been identified

Gene-Environment Interactions

The intersection of VZV neurotropism and host immune susceptibility is the best-characterized gene-environment interaction. Genetically immunocompromised individuals (e.g., HIV-positive patients) show substantially higher rates of VZV-associated cerebral vasculopathy. In mouse models, T-cell-deficient (nude and SCID) mice are susceptible to CMV-induced CNS vasculitis while immunocompetent controls are resistant, demonstrating the critical role of adaptive immunity in controlling viral entry and dissemination in the brain (PMID: 14722303). Genetic defects in innate antiviral immunity, inflammation, and autophagy have been identified in children with VZV CNS infections via whole exome sequencing (PMID: 40848267). In ABRA, the ApoE ε4 genotype predisposes to cerebral amyloid angiopathy, upon which an inflammatory autoimmune response to beta-amyloid develops (PMID: 24636849).

3. Phenotypes

Core Clinical Phenotypes

The largest systematic review and meta-analysis (n=911 PACNS patients from 46 cohort studies) established the following symptom frequencies (PMID: 34663675):

Phenotype Frequency HPO Term Type
Focal neurological signs 63% HP:0001269 (Hemiparesis) / HP:0007272 Clinical sign
Headache 51% HP:0002315 (Headache) Symptom
Cognitive impairment 41% HP:0100543 (Cognitive impairment) Behavioral
Seizures 16–36% HP:0001250 (Seizures) Clinical sign
Visual disturbances ~20% HP:0000504 (Abnormality of vision) Symptom
Aphasia ~15% HP:0002381 (Aphasia) Clinical sign
Ataxia ~10% HP:0001251 (Ataxia) Clinical sign
Altered consciousness Variable HP:0007185 (Loss of consciousness) Clinical sign
Psychiatric symptoms Variable HP:0000708 (Behavioral abnormality) Behavioral
CSF elevated protein 65–75% HP:0002922 (Elevated CSF protein) Laboratory
CSF pleocytosis 65–75% HP:0012229 (CSF pleocytosis) Laboratory

"The most frequent onset symptoms were focal neurologic signs (63%), headache (51%), and cognitive impairment (41%). Biopsy- compared with angiogram-confirmed cases had higher occurrences of cognitive impairment (55% vs 39%) and seizures (36% vs 16%), whereas focal neurologic signs occurred less often (56% vs 95%)" (PMID: 34663675)

Vessel-Size-Dependent Phenotypic Differences

PACNS phenotype varies critically by vessel caliber involved:

Feature Large-Vessel PACNS Small-Vessel PACNS p-value
Cerebrovascular events 88.9% 58.2% 0.027
Ischemic infarction 66.7% 20.7% 0.002
Tumor-like lesions 5.6% 41.4% 0.008
Limb weakness/sensory 83.3% 34.5% 0.001
Baseline mRS score 2 3 0.043
Time to treatment (days) 58.5 154 0.013

Data from PMID: 41479923: "Compared with LV-PACNS, SV-PACNS had more severe initial neurological impairment (baseline modified Rankin Scale mRS score: 3 vs. 2, p=0.043) and a longer median time from onset to treatment initiation (154 days vs. 58.5 days, p=0.013)"

Phenotype Characteristics

  • Age of onset: Median 46–48 years in adults; mean 7.89 years in pediatric cases
  • Severity: Variable — 52% had poor outcomes (mRS 3–6) in the German multicenter cohort; 18% died (PMID: 40546217)
  • Progression: Relapsing-remitting in ~50% of patients; rapidly progressive variants carry highest mortality
  • Onset pattern: Typically subacute (weeks to months); occasionally acute with stroke presentation

Quality of Life Impact

Long-term follow-up (mean 5.5 years, n=27) using validated instruments demonstrated significant residual morbidity (PMID: 30789149):

Domain (EuroQol) No Problems Some/Severe Problems
Mobility 51.9% 48.1%
Self-care 66.7% 33.3%
Usual activities 55.6% 44.4%
Pain/discomfort 51.9% 48.1%
Anxiety/depression 29.6% 70.4%

"Nineteen of 27 patients (70.4%) had mild disability; meanwhile, 5 (18.5%) had severe disability. [...] Approximately 70% of patients had minimal or no depression" (PMID: 30789149)

Intellectual functioning in pediatric CNS vasculitis: children with small-vessel disease had significantly lower FSIQ scores (81.90 vs. 94.82, p=0.04), with 24% showing intellectual disability (FSIQ <70) (PMID: 30762375).

Spinal Cord Involvement (HP:0002196)

Spinal cord PACNS is a rare but severe subset with 29% mortality at follow-up. Mainly thoracic and cervical cord involved. Granulomatous pattern most common histologically in spinal cases (PMID: 39979764).

4. Genetic/Molecular Information

Causal Genes

PACNS itself has no identified causal gene. However, several monogenic conditions cause CNS vasculitis:

Gene Condition OMIM Inheritance Key Features
ADA2 (HGNC:1839) DADA2 615688 AR Childhood-onset PAN-like vasculitis, lacunar strokes, livedo reticularis
LRBA Tregopathy 614700 AR Regulatory T-cell deficiency with autoimmune complications including CNS vasculitis
CTLA4 CHAI disease 616100 AD Immune dysregulation with CNS vasculitis
FOXP3 IPEX syndrome 304790 X-linked Multi-organ autoimmunity including CNS vasculitis
CD25/IL2RA Tregopathy 606367 AR Immune dysregulation
STAT3 (GOF) STAT3 GOF syndrome 615952 AD Multi-organ autoimmunity

DADA2 is the best-characterized monogenic cause. Autopsy findings revealed "numerous small, old infarcts throughout the brain that had not been demonstrated on prior MRI/MRA imaging" (PMID: 29963054). Patients carry compound heterozygous or homozygous mutations (e.g., c.973-2A>G splice site, p.Val458Asp missense). Anti-TNF therapy is the treatment of choice — distinct from standard PACNS treatment.

Tregopathies (LRBA, CTLA4, FOXP3/IPEX, CD25, STAT3 GOF): median onset 4.25 years, CNS vasculitis among autoimmune complications, requiring mTOR inhibitors or abatacept rather than standard immunosuppression (PMID: 41142805).

Gene Expression Profiles

Gene expression profiling of PACNS brain tissue (RNA-seq: 4 granulomatous, 5 lymphocytic, 4 ABRA vs. 4 controls) revealed significant molecular alterations (PMID: 36264136):

  • Upregulated pathways: Dendritic cell maturation, antigen processing, neuroinflammation
  • Downregulated pathways: Oxidative phosphorylation (indicating mitochondrial dysfunction)
  • Specific genes: TBC1D3C and TBC1D3L upregulation (vesicular trafficking) (PMID: 41947889)

"Pathway analysis revealed the activation of dendritic cell maturation and antigen processing as well as neuroinflammation in PCNSV versus normal brain, whereas oxidative phosphorylation was inhibited. CIBERSORT estimation of immune cell subsets suggested that activated NK cells, M1 macrophages, memory B cells, and follicular helper T cells were likely to be more prevalent in PCNSV samples" (PMID: 36264136)

Cross-Vasculitis Genetic Susceptibility

Vasculitis Key Genetic Associations Source
Behcet's disease ERAP1, CCR1-CCR3, STAT4, KLRC4, GIMAP4, TNFAIP3 PMID: 25405820
Takayasu arteritis HLA-B*52 (OR=3.29), FCGR2A/FCGR3A, IL12B PMID: 23830517
ANCA-AAV SERPINA1, SEMA6A PMID: 25405820
Kawasaki disease BLK, CD40 PMID: 25405820
Cross-vasculitis HLA region (shared) PMID: 29374629
ABRA subtype ApoE ε4/ε4 (70% of patients) PMID: 24636849

Epigenetic Information

No specific epigenetic studies have been performed on PACNS tissue. Dysregulated noncoding RNAs were identified in gene expression profiling (PMID: 36264136). In giant cell arteritis, spatial profiling revealed ECM remodeling and T-cell activation pathways in glucocorticoid-refractory cases, providing a template for future PACNS studies (PMID: 41109780).

5. Environmental Information

Infectious Agents

Post-infectious CNS vasculitis represents a significant proportion of secondary cases (PMID: 39663273):

Pathogen Mechanism Key Evidence
Varicella Zoster Virus (VZV) Transaxonal spread via trigeminal nerve to cerebral arteries Anti-VZV IgG in 32% of PACNS CSF; can cause vasculopathy without rash (PMID: 41782529)
HIV Immune compromise enables opportunistic vasculopathy VZV reactivation in 37% of HIV+ stroke patients (PMID: 35133008)
Cytomegalovirus (CMV) Monocyte-mediated CNS entry in immunodeficient hosts Meningitis, choroiditis, encephalitis, vasculitis, necrosis (PMID: 14722303)
Mycobacterium tuberculosis Granulomatous vasculitis of basal arteries Tuberculous meningitis with BBB disruption (PMID: 38675201)
Treponema pallidum Meningovascular syphilis Endarteritis obliterans of cerebral vessels (PMID: 37951699)

COVID-19 Association

SARS-CoV-2 can cause immune dysregulation leading to vasculitis, with "ischemic injury due to vasculitis" identified as a mechanism of organ dysfunction (PMID: 39692912). Post-vaccination cerebral venous sinus thrombosis has also been reported.

Environmental and Lifestyle Factors

No specific toxins, occupational exposures, or lifestyle factors (smoking, diet, exercise) have been definitively linked to PACNS development. Cardiovascular risk factors, particularly body weight, have been associated with PACNS vessel-size phenotype (PMID: 41041677).

6. Mechanism / Pathophysiology

Molecular Pathways

The pathophysiology of PACNS involves multiple interconnected immune and inflammatory cascades:

Unknown trigger (? viral, ? autoimmune, ? amyloid-related)
 │
 ▼
┌─────────────────────────────┐
│  IMMUNE ACTIVATION          │
│  • Dendritic cell maturation│
│  • Antigen processing ↑     │
│  • IL-17 ↑ in CSF           │
│  • TBC1D3C/TBC1D3L ↑       │
└─────────┬───────────────────┘
  │
  ▼
┌─────────────────────────────────────┐
│  CELLULAR INFILTRATION              │
│  • NK cells (activated) ↑           │
│  • M1 macrophages ↑                 │
│  • Memory B cells ↑                 │
│  • Follicular helper T cells ↑      │
│  • CD3/CD4/CD8/CD20 lymphocytes     │
└─────────┬───────────────────────────┘
  │
  ▼
┌─────────────────────────────────────┐
│  VASCULAR WALL DAMAGE               │
│  • Transmural inflammation           │
│  • Granulomatous reaction            │
│  • Fibrinoid necrosis                │
│  • Blood-brain barrier disruption    │
└─────────┬───────────────────────────┘
  │
  ▼
┌─────────────────────────────────────┐
│  TISSUE INJURY                       │
│  • Ischemic stroke (arterial)        │
│  • Hemorrhage (vessel rupture)       │
│  • Demyelination                     │
│  • Neuronal death (↑ NfL)            │
│  • Oxidative phosphorylation ↓       │
└─────────────────────────────────────┘

Key Molecular Findings

  1. IL-17/Th17 axis: "Recent advances in understanding pathophysiology have identified elevated interleukin-17 in cerebrospinal fluid, distinct gene expression profiles including upregulation of TBC1D3C and TBC1D3L genes, and immune cell profiling showing increased intrathecal NK-cell and B-cell frequencies" (PMID: 41947889). This is significant because anti-IL-17 therapy (secukinumab) has shown efficacy in giant cell arteritis (70% sustained remission vs. 20% placebo at week 28) (PMID: 38251601), suggesting potential translational relevance.

  2. Mitochondrial dysfunction: Oxidative phosphorylation was inhibited in PACNS tissue compared to normal brain (PMID: 36264136). GO terms: GO:0006119 (oxidative phosphorylation), GO:0005739 (mitochondrion).

  3. Dendritic cell and antigen processing activation: Consistent with autoimmune pathogenesis. GO terms: GO:0019882 (antigen processing and presentation).

  4. Tryptophan-kynurenine pathway (animal model): In MRL/lpr lupus-prone mice, cortical metabolomics revealed tryptophan metabolism diverted from serotonin toward the kynurenine pathway, with increased quinolinic acid/kynurenic acid ratio and IDO1 upregulation. "Inflammation was dominated by a Th1 cytokine program, with interferon-gamma emerging as a prominent component of the inflammatory profile. Composite cytokine scores correlated strongly with plasma NfL, establishing an immune-neuronal injury axis" (PMID: 41869319). CHEBI: CHEBI:16828 (tryptophan), CHEBI:16675 (quinolinic acid).

Immune System Involvement

Immune Component Role in PACNS Cell Ontology Evidence Source
Activated NK cells Innate immune effectors CL:0000623 PMID: 36264136
M1 macrophages Pro-inflammatory tissue damage CL:0000863 PMID: 36264136
Memory B cells Antibody-mediated pathology CL:0000787 PMID: 36264136
Follicular helper T cells B-cell help, germinal center reactions CL:0002038 PMID: 36264136
Th1 cells (IFN-gamma) Dominant in lupus CNS model CL:0000545 PMID: 41869319
IL-17/Th17 cells Vascular wall inflammation CL:0000899 PMID: 41947889
CD4+ T cells Transmural infiltration CL:0000624 PMID: 39732702
CD8+ T cells Cytotoxic effectors CL:0000625 PMID: 39732702

Tissue Damage Mechanisms

  • Ischemia: Stenotic/occlusive vasculitis causing ischemic infarcts (most common mechanism)
  • Hemorrhage: Vessel wall destruction causing parenchymal hemorrhage (55%), convexity subarachnoid hemorrhage (26%) (PMID: 28330942)
  • Fibrinoid necrosis: Vessel wall necrosis with fibrin deposition (necrotizing subtype)
  • Granulomatous inflammation: Epithelioid cell/giant cell reaction (granulomatous subtype)
  • Blood-brain barrier disruption: Enabling immune cell infiltration and edema
  • Neuroaxonal damage: Reflected by elevated NfL (PMID: 40643487)

Molecular Profiling

Transcriptomics (PMID: 36264136): RNA-seq of brain tissue revealed subtype-specific immune cell profiles via CIBERSORT: granulomatous/ABRA enriched for naive CD4 T cells and monocytes; lymphocytic for plasma cells and gamma-delta T cells.

Biomarker candidates: NfL elevated in active PACNS (serum and CSF) and may precede radiological abnormalities (PMID: 40643487; PMID: 31211179). Circulating endothelial cells proposed as differential diagnostic biomarker (PMID: 32296382).

GO Terms for Key Biological Processes

Process GO ID
Inflammatory response GO:0006954
Antigen processing and presentation GO:0019882
Oxidative phosphorylation GO:0006119
T cell activation GO:0042110
B cell activation GO:0042113
Natural killer cell activation GO:0030101
Interleukin-17 production GO:0032620
Leukocyte migration GO:0050900
Endothelial cell activation GO:0042118

7. Anatomical Structures Affected

Organ Level

  • Primary: Brain (UBERON:0000955) — principal target
  • Primary: Spinal cord (UBERON:0002240) — rare but severe subset; 29% mortality (PMID: 39979764)
  • Leptomeninges (UBERON:0000400): Enhancement in 42% of PACNS (PMID: 28330942)
  • Body systems: Nervous system (primarily), cardiovascular system (vascular component)
  • By definition, PACNS does NOT involve other organ systems

Tissue and Cell Level

  • Blood vessel walls (UBERON:0001981): Arterial wall — transmural inflammation of intima, media, adventitia
  • Cell populations:
  • Vascular endothelial cells (CL:0000071) — reactive endothelium strongly associated with sv-cPACNS (OR 8.93, p=0.001) (PMID: 39732702)
  • Vascular smooth muscle cells (CL:0000359) — vessel wall remodeling
  • Neurons (CL:0000540) — secondary ischemic/hemorrhagic damage
  • Oligodendrocytes (CL:0000128) — demyelination in some cases

Localization

  • Cerebral arteries: Most commonly multiterritorial bilateral distal involvement (42% in COVAC cohort)
  • Internal carotid artery system: 94% of cases in VZV-associated series
  • Lateralization: Usually bilateral; unilateral PACNS (U-PACNS) rare (~49 cases) — "often misdiagnosed as glioma, demyelination, or chronic encephalitis" (PMID: 40835417)

8. Temporal Development

Onset

  • Adult PACNS: Median age 46–48 years (range: adolescence to elderly)
  • Pediatric cPACNS: Mean onset 7.89 years (SD 4.17) (PMID: 30762375)
  • ABRA: Typically elderly (mean age 73 years) (PMID: 38900992)
  • Onset pattern: Usually subacute (weeks to months); median diagnostic delay 23 months (PMID: 35931755)

Progression

  • Disease course: Relapsing-remitting in ~50%; monophasic in some; rapidly progressive in a minority
  • Relapse rate: 35–50% depending on cohort and treatment
  • Course by subtype: Lymphocytic monophasic (65%); ABRA monophasic (75%); granulomatous relapsing-remitting (63%) (PMID: 40494617)

Pediatric Course

Childhood cPACNS classified by vessel size and course (PMID: 23622312): - Large-vessel non-progressive (APNP): n=49; monophasic - Large-vessel progressive (APP): n=10; chronic relapsing - Small-vessel (AN): n=21; requires biopsy; worst cognitive outcomes

Critical Periods

Diagnostic delay is a modifiable prognostic factor (HR 1.01 per month) (PMID: 40546217). "Early recognition and diagnosis of inflammatory brain diseases is critical, as the reversibility of the neurological deficits is closely related to early initiation of treatment" (PMID: 25877722).

9. Inheritance and Population

Epidemiology

Metric Value Source
Prevalence (PACNS) ~2.4 per million person-years (North America) PMID: 41947889
Sex ratio ~45–55% female; slight male predominance in most cohorts PMID: 40546217
Median age at onset 46–48 years (adults); 7.89 years (pediatric) Multiple sources
Diagnostic delay Median 23 months PMID: 35931755

Inheritance

PACNS is not a Mendelian disorder — multifactorial/polygenic susceptibility. Monogenic mimics follow specific patterns: - DADA2: Autosomal recessive (ADA2, chromosome 22q11.1) - CTLA4 haploinsufficiency: Autosomal dominant - IPEX/FOXP3: X-linked recessive - LRBA deficiency: Autosomal recessive

Population Demographics

  • No specific ethnic predilection for PACNS; most data from North American and European populations
  • For Behcet's disease (secondary CNS vasculitis): Silk Road distribution
  • For Takayasu arteritis: More common in East Asian populations
  • No known geographic clustering for PACNS

10. Diagnostics

Clinical Criteria

Calabrese and Mallek Criteria (1988) — the standard diagnostic framework: 1. Acquired neurological deficit unexplained by other diagnoses 2. Angiographic or histopathologic evidence of vasculitis within the CNS 3. No evidence of systemic vasculitis or any condition that could mimic angiographic or pathological features

Laboratory Tests

  • CSF analysis: Abnormalities in 65–75% (elevated protein, lymphocytic pleocytosis); normal CSF + normal MRI has high negative predictive value
  • NfL (Neurofilament light chain): "NfL holds potential as a biomarker for PACNS, in particular in younger patients" (PMID: 40643487). "A marked increase in NFL levels preceding the onset of neuro-axonal damage and arterial-vessel abnormalities" (PMID: 31211179)
  • ESR/CRP: Usually normal in PACNS (helps distinguish from systemic vasculitis)
  • ANCA, ANA, anti-dsDNA: Should be negative in PACNS; if positive, consider secondary causes

Imaging Studies

Modality Findings Diagnostic Value
Brain MRI Multiterritorial infarcts, WM hyperintensities, hemorrhage (55%), mass lesions Sensitivity 97–98%, low specificity
Vessel Wall MRI (VW-MRI) Concentric wall enhancement, wall thickening Improves accuracy from 36.1% to 88.8% per-lesion (PMID: 29030476)
HR-VWI LMVV: 90% strong/concentric enhancement vs. 7.1% in SVV (p<0.001) Distinguishes vessel-size subtypes (PMID: 37073640)
DSA "String of beads" pattern; alternating stenoses/dilatations Gold standard for large/medium vessel disease
SWI sequences Cerebral microbleeds, hemorrhage Sensitive marker

"IVWI can significantly improve the differentiation of nonocclusive intracranial vasculopathies when combined with traditional luminal imaging modalities" (PMID: 29030476)

Brain Biopsy

Brain and leptomeningeal biopsy remains the gold standard for small-vessel PACNS: - Biopsy diagnosed SVV in 78.3% vs. 30.8% for LMVV (p=0.022) (PMID: 37073640) - Biopsy accuracy: 100% for SVV, 57.1% for LMVV (p=0.015) - Pediatric distinction: No granulomas, necrosis, or fibrin deposits found in any pediatric sv-PACNS case. "Reactive endothelium was strongly associated with sv-cPACNS, with an OR of 8.93 (p = 0.001)" (PMID: 39732702)

Screening Algorithm

A published screening algorithm proposes (PMID: 32776287): - Major clinical features: Headache, stroke, cognitive impairment, focal neurological deficits - Minor clinical features: Seizures, altered consciousness, psychiatric disorders - Major radiological features: Multiple parenchymal lesions, parenchymal/meningeal contrast enhancement, MRA vessel abnormalities, vessel wall enhancement

MRI Hemorrhagic Spectrum

French COVAC cohort (n=60) (PMID: 28330942): "Hemorrhagic infarctions and parenchymal hemorrhages were also frequently found in the cohort (55%). Acute convexity subarachnoid hemorrhage was found in 26% of patients and 42% demonstrated pre-eminent leptomeningeal enhancement, which is found to be significantly more prevalent in biopsy-proven patients (60% versus 28%)"

CAA-RI vs BP-PACNS Differentiation

Comparison of 104 CAA-RI vs. 52 BP-PACNS patients (PMID: 38900992): CAA-RI patients older (73 vs. 45 years), more hemorrhagic signs, past ICH, ≥21 centrum semiovale perivascular spaces. BP-PACNS had more leptomeningeal enhancement and ischemic lesions.

Differential Diagnosis

Condition Distinguishing Features
RCVS Thunderclap headache, no focal deficit, convexal SAH, normal parenchyma, resolves in 3 months (PMID: 22467936)
CAA-RI Older age (73 vs. 45 years), hemorrhagic signs, ≥21 perivascular spaces
DADA2 Childhood onset, livedo reticularis, systemic inflammation, ADA2 mutations
Tumefactive PACNS Mass-like lesion mimicking glioblastoma; 34 cases, mean age 35.9 years (PMID: 41112399)
Neuro-Behcet HLA-B51+, oral/genital ulcers, CSF IL-6 elevation
NPSLE ANA/anti-dsDNA positive, multi-organ involvement
SLIPPERS Overlapping features; some cases may be PACNS variants (PMID: 41718297)
Tregopathies Pediatric multi-organ autoimmunity with CNS vasculitis (PMID: 41142805)

"Thunderclap headaches, the absence of a focal neurological deficit, a convexal subarachnoid hemorrhage and/or normal brain parenchyma on magnetic resonance imaging, and 'string of beads' appearance on conventional angiography had high diagnostic value" (PMID: 22467936)

Genetic Testing

Not routinely recommended for adult PACNS. Indicated in: - ADA2 sequencing: For childhood-onset PAN-like vasculitis with strokes - LRBA, CTLA4, FOXP3 panels: For patients with multi-organ autoimmunity + CNS vasculitis - ApoE genotyping: For suspected ABRA subtype - WES: For VZV CNS infections to identify inborn errors of immunity (PMID: 40848267)

11. Outcome/Prognosis

Survival and Mortality

Metric Value Cohort Source
Overall mortality 18% n=163, German multicenter PMID: 40546217
Poor outcome (mRS 3–6) 52% n=163, German multicenter PMID: 40546217
Good functional outcome 65.2% n=82, Indian cohort PMID: 35931755
Remission achieved 61.3% n=80, real-world PMID: 41995257
G-PACNS mortality 25% Biopsy-proven PMID: 40494617
Spinal cord PACNS mortality 29% n=38, systematic review PMID: 39979764

"Of 163 patients with PACNS (median [interquartile range (IQR)] age 48 [39-59.5] years; 73 [45%] women), 29 (18%) died, 84 (52%) had a poor outcome (modified Rankin scale [mRS] 3-6 at last follow-up), and 82 (50%) patients relapsed" (PMID: 40546217)

Prognostic Factors

Poorer survival associated with (PMID: 40546217): - Older age (HR 1.96 per 10-year increase) - Diagnostic delay (HR 1.01 per month) - Necrotizing subtype (HR 10.2, 95% CI 2.18–48.2)

Subtype-Specific Outcomes

Subtype Induction Response Median mRS Mortality
Lymphocytic Good 1–2 Low
ABRA Good Variable Moderate
Granulomatous 29% 4 (worst) 25%
Necrotizing Variable Variable Highest (HR 10.2)

"Worst outcome (median mRS 4) and highest mortality (25%) were seen in G-PACNS. Good induction treatment response was achieved in 77% of all BP-PACNS patients but was low in those with G-PACNS (29%)" (PMID: 40494617)

12. Treatment

Pharmacotherapy

No randomized controlled trials exist for PACNS treatment. All recommendations are based on observational studies and expert consensus.

Induction Therapy

Agent Class Evidence MAXO Term
Glucocorticoids Corticosteroid Standard of care; pulse then taper MAXO:0000609
Cyclophosphamide Alkylating agent HR 0.44 (95% CI 0.22–0.86) for relapse reduction (PMID: 40546217) MAXO:0001298
Rituximab (refractory) Anti-CD20 mAb Combined CYC+RTX effective in rapidly progressive PACNS (PMID: 39954605) MAXO:0001380

"Patients treated with cyclophosphamide alone or in combination with steroids had a lower incidence of relapse than untreated patients (HR, 0.44 [95% CI, 0.22-0.86]; HR, 0.47 [95% CI, 0.24-0.92])" (PMID: 40546217)

Maintenance Therapy

Agent Evidence MAXO Term
Mycophenolate mofetil No relapses over mean 29 months in pediatric cases (PMID: 28034820) MAXO:0001077
Azathioprine Commonly used maintenance MAXO:0001069
Methotrexate Long-term immunosuppression MAXO:0001084
Rituximab Relapsed/refractory cases MAXO:0001380

"In all children, no relapse of cerebral vasculitis occurred during the whole follow-up period and all of them improved while in MMF treatment" (PMID: 28034820)

Treatment Response

  • Overall remission: 61.3%; favorable functional outcomes: 87.5% (PMID: 41995257)
  • Good induction response: 77% overall, but only 29% in granulomatous subtype (PMID: 40494617)
  • Relapse rate: 35% overall

Treatment Complications

  • Glucocorticoid use before ICH may worsen bleeding severity in AAV patients (p<0.001) (PMID: 40643697)
  • Standard immunosuppression risks: infections, bone marrow suppression, infertility (cyclophosphamide), PML (rituximab, rare)

Treatment Algorithm

Suspected PACNS
      │
      ▼
Glucocorticoid pulse (methylprednisolone 1g/day × 3-5 days)
      │
      ▼
Induction: GC + Cyclophosphamide (3-6 months)
      │
      ├── Response → Maintenance: MMF or AZA or MTX (2-3 years)
      │
      ├── Refractory → Rituximab ± CYC combination
      │
      └── Rapidly progressive → CYC + RTX + GC (triple therapy)

Advanced and Experimental Therapeutics

  • Anti-IL-17 (secukinumab): 70% sustained remission in GCA vs. 20% placebo (PMID: 38251601) — rational candidate for PACNS given elevated CSF IL-17
  • Anti-TNF: First-line for DADA2; efficacious in Neuro-Behcet
  • Anti-IL-6 (tocilizumab): Established in GCA; potential in CNS vasculitis
  • Abatacept/mTOR inhibitors: Required for Tregopathies causing CNS vasculitis (PMID: 41142805)
  • Mepolizumab (anti-IL-5): For EGPA-related CNS vasculitis (PMID: 38109745)
  • Anifrolumab (anti-IFNAR): Glucocorticoid-sparing in NPSLE (PMID: 41211782)

Pharmacogenomics

  • TPMT/NUDT15 genotyping: For azathioprine dosing (CPIC guidelines)
  • CYP2B6: Affects cyclophosphamide metabolism
  • ApoE genotype: Influences ABRA treatment response and prognosis

13. Prevention

Primary Prevention

No primary prevention strategies exist for PACNS. For secondary CNS vasculitis: - VZV vaccination: May reduce VZV vasculopathy risk - HIV treatment: Antiretroviral therapy reduces opportunistic CNS vasculitis - Treatment of underlying systemic vasculitis: Prevents secondary CNS involvement

Secondary Prevention (Early Detection)

  • High clinical suspicion in young stroke patients with multiterritorial infarcts
  • VW-MRI as screening tool when clinical/radiological "major features" are present
  • NfL monitoring: Can precede radiological abnormalities (PMID: 31211179)
  • Genetic screening for ADA2 mutations in childhood-onset vasculitis/stroke

Tertiary Prevention

  • Long-term maintenance immunosuppression to prevent relapse
  • Regular neuroimaging surveillance
  • NfL monitoring for early relapse detection
  • Rehabilitation: physical, occupational, cognitive, and speech therapy
  • Psychological support for anxiety/depression (affecting >70% long-term)

14. Other Species / Natural Disease

Naturally Occurring CNS Vasculitis in Animals

Species Condition Mechanism Source
Dog (Canis lupus familiaris, NCBI Taxon: 9615) Encephalitozoonosis Encephalitozoon cuniculi parasitizes endothelial cells, causing granulomatous vasculitis PMID: 750958
Dog Trypanosomiasis Trypanosoma brucei causes necrotizing vasculitis with CNS involvement PMID: 6110340

"Vasculitis is demonstrated as the underlying lesion of canine encephalitozoonosis affecting the brain and is suggested to be the basic factor in the pathogenesis of this disease" (PMID: 750958)

No well-documented natural disease equivalent to human primary/idiopathic PACNS exists in other species.

15. Model Organisms

Available Models

Model Type Key Findings Limitations
MRL/lpr mouse Spontaneous lupus IFN-gamma-dominated Th1; NfL-cytokine correlation; kynurenine pathway diversion (PMID: 41869319) Systemic disease, not isolated CNS
Nude/SCID + CMV Induced viral CNS vasculitis, meningitis, necrosis; requires immunodeficiency (PMID: 14722303) Not autoimmune
ACE inhibitor MRL/lpr Pharmacological Centrally-acting ACE inhibitors suppress IFN responses (PMID: 33042154) Limited to lupus model

Key Model Findings

The MRL/lpr mouse reveals critical mechanistic insights: 1. Immune-neuronal injury axis: Composite cytokine scores correlated with plasma NfL (PMID: 41869319) 2. Region-specific cytokine signatures: Hippocampal IL-10 loss, frontal cortex IFN-gamma dominance 3. Metabolic remodeling: Tryptophan diverted to neurotoxic kynurenine pathway 4. Important negative result: Anti-IFNAR treatment "did NOT improve neuropsychiatric disease despite decreasing IFN-stimulated genes" — "no significant differences were seen between the anti-IFNAR- and control-treated mice when assessing for depression-like behavior or cognitive dysfunction" (PMID: 31474191)

Model Limitations

  • No spontaneous model exactly recapitulates human PACNS
  • MRL/lpr models systemic lupus with secondary CNS involvement
  • Viral models require immunodeficiency
  • Species differences in cerebrovascular anatomy and immune surveillance

Mechanistic Model: Integrated Pathophysiology

Synthesizing all evidence, the following mechanistic model emerges for PACNS:

UPSTREAM TRIGGERS
├── Viral reactivation (VZV, CMV) ──────────────┐
├── Autoimmune predisposition (HLA, ERAP1) ─────┤
├── Amyloid deposition (ApoE ε4 → ABRA) ────────┤
└── Monogenic defects (ADA2, LRBA, CTLA4) ──────┘
                                  │
                                  ▼
      IMMUNE ACTIVATION IN CNS VESSELS
      ├── IL-17/Th17 activation (CSF IL-17 ↑)
      ├── Dendritic cell maturation
      ├── NK cell activation
      ├── M1 macrophage polarization
      ├── Memory B cell/plasma cell expansion
      └── TBC1D3C/TBC1D3L upregulation
                                  │
                                  ▼
      VASCULAR WALL INFLAMMATION
      ├── Lymphocytic infiltration (65%)
      ├── Granulomatous reaction (14%)
      ├── Fibrinoid necrosis (5%)
      └── ABRA (amyloid + inflammation) (16%)
                                  │
                                  ▼
      DOWNSTREAM CONSEQUENCES
      ├── Ischemic stroke (stenosis/occlusion)
      ├── Hemorrhage (55%) (vessel destruction)
      ├── Mitochondrial dysfunction (OXPHOS ↓)
      ├── BBB disruption → edema
      ├── Kynurenine pathway diversion (quinolinic acid ↑)
      └── Neuroaxonal injury (NfL ↑)
                                  │
                                  ▼
      CLINICAL MANIFESTATIONS
      ├── Focal deficits (63%)
      ├── Headache (51%)
      ├── Cognitive impairment (41%)
      ├── Seizures (16-36%)
      └── Long-term: anxiety/depression (70.4%)

Translational implications: The convergence of elevated CSF IL-17 in PACNS (PMID: 41947889) with the success of anti-IL-17A therapy (secukinumab) in giant cell arteritis (70% sustained remission, PMID: 38251601) identifies IL-17 inhibition as the most rational translational therapeutic candidate for PACNS. The negative anti-IFNAR result in MRL/lpr mice (PMID: 31474191) cautions against targeting type I interferons alone.

Evidence Base

This report synthesizes evidence from 113 papers, including:

Paper Type Key Examples Count
Systematic reviews/meta-analyses PMID: 34663675 (n=911 PACNS) 8+
Multicenter cohort studies PMID: 40546217 (n=163) 5+
Single-center cohorts PMID: 40494617 (n=57 biopsy-proven) 10+
Gene expression/molecular PMID: 36264136 3+
Genetics studies PMID: 29374629, PMID: 25405820 5+
Animal model studies PMID: 41869319, PMID: 31474191 5+
Comprehensive reviews PMID: 41947889 15+
Case reports/series PMID: 29963054 20+

Limitations and Knowledge Gaps

  1. No GWAS for PACNS: Disease too rare; genetic susceptibility inferred from cross-vasculitis analyses
  2. No randomized controlled trials: All treatment evidence observational; multicenter RCTs urgently needed
  3. Diagnostic uncertainty: Up to 40–50% initially misdiagnosed; biopsy sensitivity only 57% for large-vessel disease
  4. Limited molecular profiling: Only one gene expression study; no proteomics, metabolomics, or single-cell studies in human PACNS tissue
  5. Animal model limitations: No model recapitulates primary PACNS; available models reflect secondary CNS vasculitis
  6. Pediatric data scarcity: Smaller cohorts; distinct pathology from adults but treatment extrapolated
  7. Biomarker validation: NfL promising but not validated in large prospective PACNS cohorts
  8. Long-term outcome data: Limited follow-up beyond 5 years; late complications poorly characterized
  9. Subtype classification heterogeneity: Different classification systems across studies limit comparison
  10. Quality of life data: Limited to single study with small sample (n=27) and 34.6% response rate

Proposed Follow-up Experiments/Actions

Immediate Priorities

  1. Multicenter PACNS registry: Establish a prospective international registry with standardized phenotyping, biobanking, and outcome measures to enable future GWAS and clinical trials
  2. NfL validation study: Prospective longitudinal cohort measuring serum/CSF NfL at diagnosis, during treatment, and at relapse to establish clinical utility thresholds
  3. Single-cell RNA-seq of brain biopsies: Profile cell-type-specific transcriptomic signatures in PACNS subtypes to identify therapeutic targets

Medium-term Goals

  1. IL-17 inhibitor pilot trial: Based on elevated CSF IL-17 in PACNS and secukinumab efficacy in GCA (70% sustained remission), a pilot study in refractory PACNS is warranted
  2. PACNS genetic study: Whole-exome sequencing of well-phenotyped PACNS patients vs. controls to identify disease-specific susceptibility variants
  3. CSF proteomics/metabolomics: Unbiased profiling across subtypes for diagnostic biomarkers and therapeutic targets
  4. VZV investigation: Systematic CSF VZV antibody testing in all PACNS patients to determine proportion with occult viral triggers

Long-term Vision

  1. Precision medicine framework: Develop subtype-specific treatment algorithms based on histopathology, gene expression, and biomarker profiles
  2. Machine learning diagnostic tool: Integrate clinical, imaging, laboratory, and molecular data for automated PACNS probability scoring
  3. Kynurenine pathway modulation: Evaluate IDO1 inhibitors as adjunctive neuroprotective therapy based on animal model evidence

Ontology Term Summary

Category Terms
MONDO MONDO:0007141 (cerebral vasculitis)
HPO HP:0002315 (Headache), HP:0001269 (Hemiparesis), HP:0100543 (Cognitive impairment), HP:0001250 (Seizures), HP:0000504 (Abnormality of vision), HP:0002381 (Aphasia), HP:0001251 (Ataxia), HP:0002922 (Elevated CSF protein), HP:0012229 (CSF pleocytosis)
GO (BP) GO:0006954 (inflammatory response), GO:0019882 (antigen processing and presentation), GO:0006119 (oxidative phosphorylation), GO:0042110 (T cell activation), GO:0042113 (B cell activation), GO:0030101 (NK cell activation), GO:0032620 (IL-17 production), GO:0050900 (leukocyte migration), GO:0042118 (endothelial cell activation)
GO (CC) GO:0005739 (mitochondrion), GO:0005768 (endosome), GO:0005840 (ribosome)
CL CL:0000623 (NK cell), CL:0000863 (M1 macrophage), CL:0000787 (memory B cell), CL:0002038 (T follicular helper cell), CL:0000071 (endothelial cell), CL:0000540 (neuron), CL:0000624 (CD4+ T cell), CL:0000625 (CD8+ T cell)
UBERON UBERON:0000955 (brain), UBERON:0002240 (spinal cord), UBERON:0000400 (leptomeninx), UBERON:0001981 (blood vessel)
CHEBI CHEBI:16828 (tryptophan), CHEBI:16675 (quinolinic acid), CHEBI:28790 (serotonin), CHEBI:57959 (kynurenine)
MAXO MAXO:0000609 (corticosteroid therapy), MAXO:0001298 (cyclophosphamide therapy), MAXO:0001380 (rituximab therapy), MAXO:0001077 (MMF therapy), MAXO:0001069 (azathioprine therapy), MAXO:0001084 (methotrexate therapy), MAXO:0000127 (brain biopsy)

Report generated through systematic PubMed literature review covering 113 publications across 5 research iterations. 13 confirmed findings recorded with statistical evidence and 40+ unique PMID citations with verbatim abstract quotes. Ontology annotations include HPO, GO, CL, UBERON, CHEBI, MAXO, and MONDO terms. Information current as of May 2026.