| Source (first author year, journal) | Study type/setting | N | Key diagnostic criteria/definition highlights | Key clinical features with frequencies | Key diagnostic test findings (CSF/EEG/MRI/PET) | Treatment(s) and response/relapse statistics | Notes/controversies | PMID | DOI/URL | Publication date |
|---|---|---:|---|---|---|---|---|---|---|---|
| Dumrikarnlert 2023, *BMC Neurology* | Retrospective tertiary-center cohort, Siriraj Hospital (Thailand), acute encephalopathy referrals | 204 screened; 31 thyroid Ab+; 13 met HE criteria | Required encephalopathy with neuropsychiatric features, serum anti-TPO and/or anti-Tg positivity, negative neuronal antibodies in serum/CSF, thyroid disease typically euthyroid/subclinical, normal or nonspecific MRI, and exclusion of alternative causes (Table 3). HE should be considered in unexplained subacute cognitive impairment or cerebellar ataxia. (pqac-00000008, pqac-00000009, pqac-00000013, pqac-00000027) | Cognitive impairment 76.9%; clouding of consciousness 46.2%; ataxia 46.2%; seizures 38.5% with status epilepticus 23.1%; sleep disturbance 38.5%; behavior change 30.8%; visual hallucinations 30.8%; mood disturbance 23.1%; abnormal movement 23.1%; stroke-like episodes 15.4%. (pqac-00000009, pqac-00000013) | CSF pleocytosis 15.4%; elevated CSF protein 46.2%; MRI generally nonspecific white-matter changes; autoimmune/paraneoplastic panels negative by inclusion; authors note MRI and labs are nonspecific. (pqac-00000008, pqac-00000012, pqac-00000013) | Corticosteroids in 12/13: marked improvement 75%, slight improvement 8.3%, no improvement 16.6%; 1 untreated patient died. (pqac-00000008, pqac-00000009, pqac-00000013) | Identifiable among acute encephalopathy presentations, but remains diagnosis of exclusion; MRI and CSF lack specificity. (pqac-00000008, pqac-00000009) |  | 10.1186/s12883-023-03305-4; https://doi.org/10.1186/s12883-023-03305-4 | Sep 2023 |
| Lee 2024, *Acta Neurologica Belgica* | Single-center retrospective study of unexplained mental dysfunction | 198 total; 86 tested for ATA; 22 probable HE | Proposed probable HE criteria: altered mentation, rapid cognitive impairment, or myoclonus of unknown cause; ATA positivity; no significant free T4 abnormality or overt thyroid symptoms; no other definite autoimmune disorder; no paraneoplastic or ALE antibodies; CSF not mandatory. (pqac-00000014) | Clinical seizures in 7 patients; cohort selected from altered mentation, rapidly progressive cognitive decline, or myoclonus. ATA positivity 29.1%; probable HE rate 25.6% among tested patients. (pqac-00000014) | EEG showed NCSE in 6 patients, often intractable to antiepileptic drugs; neuroimaging may show vasogenic or cytotoxic edema patterns and vascular enhancement responding to steroids; elevated 14-3-3 may complicate distinction from CJD. (pqac-00000011, pqac-00000014) | Immunosuppressants and steroids were first-line; 19/21 treated patients had good outcomes (90.5%); lack of immunosuppression correlated with poorer outcomes. (pqac-00000011, pqac-00000014) | Suggests possible under-recognition; broader criteria than Graus may increase probable HE classification. (pqac-00000011, pqac-00000014) |  | 10.1007/s13760-024-02520-1; https://doi.org/10.1007/s13760-024-02520-1 | Jun 2024 |
| Pempera 2024, *International Journal of Molecular Sciences* | Systematic and critical review through Feb 2024 | 6 included studies after screening 2,443 records | HE or SREAT is rare, poorly understood, and lacks a specific marker. Negative anti-TPO may help rule out HE, but positive anti-TPO cannot confirm it; anti-NAE is non-specific. (pqac-00000000) | Review-level summary includes recurrent cognitive disorders, impaired mental status, hallucinations, stroke-like events, and mixed psychiatric-neurologic phenotypes. (pqac-00000000) | No specific biomarker identified; anti-thyroid titers do not correlate with severity; antithyroid antibodies not demonstrated in CNS tissue at autopsy; available diagnostic test data were heterogeneous. (pqac-00000000) | Pooled glucocorticoid effectiveness 60.94%; relapse after treatment 31.67%. (pqac-00000000) | Emphasizes limited high-quality evidence and overreliance on nonspecific thyroid antibodies. (pqac-00000000) |  | 10.3390/ijms25137101; https://doi.org/10.3390/ijms25137101 | Jun 2024 |
| Chaudhuri 2023, *Current Neurology and Neuroscience Reports* | Narrative review with case series and literature synthesis | Not stated | Defines HE or SREAT as altered mental status, confusion, hallucinations, delusions, and sometimes seizures with high serum antithyroid antibodies and usual steroid responsiveness; diagnosis requires exclusion of autoimmune encephalitis including anti-IgLON5 and paraneoplastic causes. (pqac-00000005, pqac-00000006) | Core manifestations include subacute encephalopathy, neuropsychiatric symptoms, seizures, status epilepticus or NCSE, fluctuating consciousness, and rapidly progressive dementia; psychiatric misdiagnosis is common. (pqac-00000005, pqac-00000006) | MRI and CSF are often normal or nonspecific; CSF may show raised protein and mild lymphocytic pleocytosis; EEG commonly shows generalized slowing without epileptiform discharges. (pqac-00000006) | Corticosteroids remain mainstay; some clinicians use early oral steroids or IVIG plus steroids; no standardized steroid dose or duration guidelines. (pqac-00000005, pqac-00000006) | Stresses thyroid antibodies are nonspecific and may be markers rather than pathogenic; discusses possible IgG4-related aggressive phenotype. (pqac-00000005, pqac-00000006) |  | 10.1007/s11910-023-01255-5; https://doi.org/10.1007/s11910-023-01255-5 | Feb 2023 |
| Valencia-Sanchez 2021, *Brain Communications* | Mayo Clinic retrospective referral series for suspected HE or SREAT | 144 referred thyroid Ab-positive patients | Evaluated suspected HE using objective neurologic workup and Graus-based autoimmune encephalitis criteria. Thyroid antibody positivity alone had little diagnostic value; all but 3 autoimmune CNS cases met Graus criteria, whereas none of the non-autoimmune group did when full exclusion criteria were applied. (pqac-00000007, pqac-00000021, pqac-00000022, pqac-00000024) | 39/144 or 27% had autoimmune CNS disorders; 105/144 or 73% had alternative diagnoses. Features favoring autoimmune CNS disease included subacute onset 82.1% vs 27.6%, seizures, stroke-like episodes, aphasia, ataxia, and prior autoimmune history. (pqac-00000007, pqac-00000021, pqac-00000023, pqac-00000024) | MRI abnormalities 20.5% vs 3.8%; abnormal EEG 42.4% vs 16.5%; inflammatory CSF 51.3% vs 22.7%; CSF WBC greater than 5 cells per µL 23.1% vs 1.1%; oligoclonal bands 13.3% vs 0%; TPO titers did not differ between groups. (pqac-00000007, pqac-00000023, pqac-00000024) | Responders more often had inflammatory CSF; subjective improvement also occurred in some alternative diagnoses; relapse occurred in 6/11 with at least 6 months follow-up. (pqac-00000020, pqac-00000022, pqac-00000025) | Strong evidence for overdiagnosis and misdiagnosis; thyroid antibodies are common and of little value beyond autoimmune thyroid disease. (pqac-00000007, pqac-00000022, pqac-00000024) |  | 10.1093/braincomms/fcaa233; https://doi.org/10.1093/braincomms/fcaa233 | Jan 2021 |
| Graus 2016, *The Lancet Neurology* | International expert clinical diagnostic framework for autoimmune encephalitis | Not applicable | Positions Hashimoto encephalopathy or SREAT as a controversial entity to be diagnosed cautiously as probable autoimmune encephalitis only after rigorous exclusion. Panel 6 criteria: encephalopathy with seizures, myoclonus, hallucinations, or stroke-like episodes; subclinical or mild thyroid disease; normal or nonspecific MRI; serum thyroid antibodies; absence of well-characterized neuronal antibodies in serum and CSF; reasonable exclusion of alternatives. (pqac-00000016, pqac-00000019) | Not a frequency study; focuses on syndrome definition and differential diagnosis. (pqac-00000016, pqac-00000019) | Framework uses history and examination plus CSF, MRI, and EEG; notes thyroid antibodies lack specificity and occur in about 13% of healthy people, more often in older women; alpha-enolase antibodies not reliable. (pqac-00000016) | Steroid responsiveness historically informed the entity, but immunotherapy should follow comprehensive exclusion of mimics. (pqac-00000016) | Foundational criteria paper used to avoid misclassification of thyroid-antibody-positive encephalopathy. (pqac-00000016, pqac-00000019) |  | 10.1016/S1474-4422(15)00401-9; https://doi.org/10.1016/S1474-4422(15)00401-9 | Apr 2016 |
| Laurent 2016, *Autoimmunity Reviews* | Literature review and systematic compilation of reported SREAT cases | 251 cases | Defined SREAT or HE as encephalopathy with anti-thyroid antibodies and no alternative cause; controversy remained whether it is antibody-mediated encephalitis or nonspecific encephalopathy linked to thyroid autoimmunity. (pqac-00000004, pqac-00000010) | Median age 52; 73% female. Seizures 47%; confusion 46%; memory impairment 43%; speech disorder 37%; gait disturbance 27%; persecutory delusions 25%; myoclonus 22%; headaches 16%; coma 15%; depression 12%; isolated progressive memory impairment 11%; isolated psychiatric disorder 10%. (pqac-00000004, pqac-00000010) | All had elevated anti-thyroid antibodies; 69% both anti-TPO and anti-Tg, 34% only anti-TPO, 7% only anti-Tg; median TSH normal at 2 UI/mL; 32% had known thyroid disease. Aggregated CSF, EEG, and MRI details were not provided in the excerpt. (pqac-00000004, pqac-00000010) | Steroids were usually first-line; dose, duration, and predictors of failure remained unresolved; steroid dependence and relapses occurred. (pqac-00000004) | Important historical benchmark for symptom frequencies, but many included reports predated modern neuronal antibody testing. (pqac-00000004, pqac-00000010) |  | 10.1016/j.autrev.2016.09.008; https://doi.org/10.1016/j.autrev.2016.09.008 | Dec 2016 |


*Table: This table summarizes the most informative recent and landmark studies on Hashimoto encephalopathy or SREAT, emphasizing diagnostic criteria, test findings, treatment outcomes, and controversies. It is useful for quickly comparing how modern studies refine or challenge the traditional HE or SREAT concept.*