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Conditions with similar clinical presentations that must be differentiated from Semicircular Canal Dehiscence Syndrome:
name: Semicircular Canal Dehiscence Syndrome
creation_date: '2026-01-08T22:33:12Z'
updated_date: '2026-05-11T00:00:00Z'
category: Structural
disease_term:
preferred_term: semicircular canal dehiscence syndrome
term:
id: MONDO:0018484
label: semicircular canal dehiscence syndrome
parents:
- Inner Ear Disease
- Vestibular Disorder
synonyms:
- Superior Canal Dehiscence Syndrome
- SCDS
- Superior Semicircular Canal Dehiscence
- Third Window Syndrome
- Minor Syndrome
pathophysiology:
- name: Developmental Otic Capsule Bone Deficiency
description: >-
Incomplete postnatal ossification of the bone overlying the superior semicircular
canal produces a constitutionally thin otic capsule that persists into adulthood
in a subset of individuals. The bone over the superior canal is uniformly thin
at birth and normally thickens through early childhood; failure of this maturation
leaves a stable population of adults with thin (but not yet dehiscent) bone
that is the substrate for later acquired dehiscence ("Hit 1" of the two-hit model).
The deficiency is not focal: SCDS patients show generalized thinning of the
otic capsule and skull base.
locations:
- preferred_term: superior semicircular canal
term:
id: UBERON:0001841
label: anterior semicircular canal
- preferred_term: otic capsule
term:
id: UBERON:0005411
label: bony otic capsule
cell_types:
- preferred_term: osteoblast
term:
id: CL:0000062
label: osteoblast
biological_processes:
- preferred_term: endochondral ossification of the otic capsule
term:
id: GO:0001958
label: endochondral ossification
modifier: DECREASED
evidence:
- reference: PMID:10680863
reference_title: "Dehiscence or thinning of bone overlying the superior semicircular canal in a temporal bone survey."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Specimens from infants demonstrated uniformly thin bone over the superior
canal in the middle fossa at birth, with gradual thickening until 3 years
of age.
explanation: >-
Establishes the developmental trajectory of postnatal SSC bone thickening
that defines who remains at risk in adulthood.
- reference: PMID:10680863
reference_title: "Dehiscence or thinning of bone overlying the superior semicircular canal in a temporal bone survey."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These abnormalities may arise from failure of postnatal bone development.
Thin areas of bone over the superior canal may be predisposed to disruption
by trauma.
explanation: >-
Authors explicitly frame the developmental-failure-plus-trauma hypothesis
that underpins the two-hit pathogenesis model.
- reference: PMID:25406876
reference_title: "The relationship of age and radiographic incidence of superior semicircular canal dehiscence in pediatric patients."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
dehiscent or thin canal existed in 51.4% of children less than 12 months,
17.5% of children between 1 and 2 years, 18.5% of children between 3 and
10 years, and 10.9% of children between 11 and 18 years.
explanation: >-
Pediatric CT data quantify the postnatal ossification trajectory and the
residual at-risk population (~11%) entering adulthood.
- reference: PMID:21393404
reference_title: "Superior semicircular canal dehiscence: congenital or acquired condition?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Each successively older age category experienced a 93% increase (95% CI,
30%-187%) in the prevalence of SSCD (P = .001) and a 9% increase (95% CI,
-5%-25%) in the prevalence of thinning (P = .21).
explanation: >-
The age-dissociation between thinning (stable, congenital) and frank
dehiscence (age-progressive, acquired) is the central evidence for a
two-hit model.
- reference: PMID:25998441
reference_title: "Thickness of the bony otic capsule: etiopathogenetic perspectives on superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The SC of the unaffected side in the SCD group (n = 11, 0.41 ± 0.23 mm)
was significantly thinner than the one in the control group (n = 68, 0.64
± 0.21 mm, p = 0.002).
explanation: >-
Demonstrates that the contralateral, asymptomatic side in SCDS patients
is also thin, supporting a systemic developmental predisposition rather
than a focal acquired lesion.
- reference: PMID:41941208
reference_title: "Skull Base Deficiency in Superior Semicircular Canal Dehiscence (SSCD): Evidence for Incomplete Development."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
SSCD patients possess dramatically thinner skull bases than control and
sCSFL patients, despite a lack of predisposing factors like obesity.
explanation: >-
Skull base deficiency in SSCD is generalized and is not attributable to
obesity-driven mechanisms seen in spontaneous CSF-leak patients,
implicating a primary developmental defect.
- reference: PMID:41941208
reference_title: "Skull Base Deficiency in Superior Semicircular Canal Dehiscence (SSCD): Evidence for Incomplete Development."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These data implicate a developmental deficiency in the pathophysiology
of SSCD.
explanation: >-
Authors directly conclude developmental deficiency drives SSCD, distinct
from obesity/ICP-mediated skull base attenuation seen in CSF-leak patients.
- reference: PMID:8883642
reference_title: "Imaging findings of the developing temporal bone in fetal specimens."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The otic capsule develops from a cartilage model. Ossification of the
otic capsule proceeds rapidly between 18 and 24 weeks from multiple
ossification centers that replace the cartilaginous framework.
explanation: >-
Establishes the prenatal timing of otic capsule ossification, the
developmental window in which the substrate for SCDS predisposition is laid.
- reference: PMID:41218633
reference_title: "Closure of Congenital Semicircular Dehiscence in the First 10 Years of Life."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The mean thickness of the bone over the site of the previous dehiscence
was 1 mm (range 0.2-3.3 mm).
explanation: >-
Longitudinal pediatric imaging shows that congenital dehiscences are
typically covered by normal bone growth by puberty, sharpening the
distinction between transient infantile thinning and persistent adult
predisposition.
downstream:
- target: Bony Dehiscence of Semicircular Canal
description: >-
Persistent thin otic capsule bone provides the structural substrate on
which environmental insults (Hit 2) produce frank dehiscence.
evidence:
- reference: PMID:25998441
reference_title: "Thickness of the bony otic capsule: etiopathogenetic perspectives on superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
These results suggest that both embryological and acquired factors
affect the occurrence of SCD.
explanation: >-
The authors' synthesis frames dehiscence as the product of
developmental thin bone plus acquired insult.
- name: Endochondral-Intramembranous Junction Vulnerability
description: >-
The superior semicircular canal sits at an embryologic junction: the tegmental
prolongation of the tegmen tympani and the superior semicircular canal arise
from the same otic capsule and undergo endochondral ossification, while the
squamous prolongation of the tegmen ossifies intramembranously. The shared
otic-capsule origin and common periosteum at this junction explain the
striking co-occurrence of tegmen tympani dehiscence and SSCD, and identify
a focal anatomical weak point.
locations:
- preferred_term: superior semicircular canal
term:
id: UBERON:0001841
label: anterior semicircular canal
- preferred_term: tegmen tympani
term:
id: UBERON:0006837
label: tegmen tympani
- preferred_term: middle cranial fossa
term:
id: UBERON:0003722
label: middle cranial fossa
biological_processes:
- preferred_term: endochondral ossification at the otic capsule-tegmen junction
term:
id: GO:0001958
label: endochondral ossification
evidence:
- reference: PMID:26738982
reference_title: "Ontogenetic explanation for tegmen tympani dehiscence and superior semicircular canal dehiscence association."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The tegmental prolongation of tegmen tympani and superior semicircular
canal originate from the same structure, the otic capsule, and have the
same type of endochondral ossification
explanation: >-
Direct embryological evidence for shared developmental origin of SSC and
tegmen, the basis for the junction-vulnerability hypothesis.
- reference: PMID:26738982
reference_title: "Ontogenetic explanation for tegmen tympani dehiscence and superior semicircular canal dehiscence association."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
both structures share a common layer of external periosteum could explain
the coexistence of lack of bone coverage in tegmen and superior
semicircular canal.
explanation: >-
Shared periosteum at the SSC-tegmen junction provides a mechanistic link
for co-occurrent dehiscence.
- reference: PMID:37777625
reference_title: "Association of the superior semicircular canal and tegmen tympani dehiscences and its relationship with the pneumatisation of the temporal bone."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Of the 124 cases studied, 35 (28.2%) presented both dehiscences.
explanation: >-
Quantifies SSCD-tegmen co-occurrence at ~28%, far above the SCDS base rate,
consistent with shared embryologic vulnerability.
- reference: PMID:22429945
reference_title: "Spontaneous tegmen defect and semicircular canal dehiscence: same etiopathogenic entity?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Semicircular canal dehiscence was associated to STD in 13 patients. Of
these patients, 12 (95%) had protruding superior semicircular canals in
the middle cranial fossa versus only 3 (30%) of 10 patients for the
nondehiscent cases.
explanation: >-
SSC protrusion into the middle cranial fossa is strongly enriched in
tegmen-defect patients with co-occurring SSCD, identifying a shared
anatomic risk axis.
- reference: PMID:22429945
reference_title: "Spontaneous tegmen defect and semicircular canal dehiscence: same etiopathogenic entity?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Protrusion of the superior semicircular canal in the middle cranial
fossa is probably an additional factor underlying STD and SCCD
etiopathogeny.
explanation: >-
Author synthesis attributes co-occurrence to a shared anatomical
etiopathogeny at the SSC-tegmen junction.
downstream:
- target: Bony Dehiscence of Semicircular Canal
description: >-
Shared embryologic origin and protrusion of the SSC into the middle
cranial fossa concentrate developmental and mechanical vulnerability at
the otic-capsule/tegmen junction, predisposing to SSC dehiscence.
evidence:
- reference: PMID:22429945
reference_title: "Spontaneous tegmen defect and semicircular canal dehiscence: same etiopathogenic entity?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Protrusion of the superior semicircular canal in the middle cranial
fossa is probably an additional factor underlying STD and SCCD
etiopathogeny.
explanation: >-
Supports the upstream-to-dehiscence edge: junction-zone anatomy is a
contributor to dehiscence formation.
- name: Bony Dehiscence of Semicircular Canal
description: >-
An abnormal opening or thinning in the bone overlying the superior semicircular
canal creates a pathological third mobile window in the inner ear, in addition
to the oval and round windows. Dehiscence is best understood as the product
of two hits: a congenital developmental thin-bone substrate (failure of
postnatal otic capsule ossification, generalized skull base deficiency) and
an acquired second hit from age-related remodeling or environmental triggers
(trauma, Valsalva-type pressure events, noise/pressure exposure).
locations:
- preferred_term: superior semicircular canal
term:
id: UBERON:0001841
label: anterior semicircular canal
- preferred_term: otic capsule
term:
id: UBERON:0005411
label: bony otic capsule
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Histopathologic examination of the right ear showed a 1.4 x 0.6-mm dehiscence
of bone covering the superior canal. Dura was in direct contact with the endosteum
and the membranous duct at the level of the dehiscence.
explanation: >-
Histopathological examination confirmed the anatomical basis of the dehiscence
with direct dura-to-membranous duct contact at the bony defect.
downstream:
- target: Third Window Effect
description: >-
The bony defect creates a pathological third mobile window in the inner ear labyrinth.
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Superior canal dehiscence causes vestibular and auditory symptoms and signs
as a consequence of the third mobile window in the inner ear created by
the dehiscence.
explanation: >-
Clinical series conclusion directly supports that the canal dehiscence creates
the third-window lesion.
- name: Third Window Effect
description: >-
The dehiscence acts as a third mobile window that shunts acoustic energy away
from
the cochlea and toward the vestibular system. A third window introduces a low
mechanical impedance, shunting part of the inner ear fluid pressure and fluid
volume flow at the site of the window.
biological_processes:
- preferred_term: vestibular receptor stimulus detection
term:
id: GO:0050973
label: detection of mechanical stimulus involved in equilibrioception
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
If sufficiently large, a third window will introduce a low mechanical impedance,
thus shunting part of the inner ear fluid pressure and fluid volume flow at
the
site of the window.
explanation: >-
This biomechanical review explains how the dehiscence creates abnormal fluid
dynamics by introducing a low-impedance pathway.
- reference: PMID:18223508
reference_title: "Conductive hearing loss caused by third-window lesions of the inner ear."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
A number of disparate disorders affecting the labyrinth can produce CHL by
acting as a pathologic third window in the inner ear. The common denominator
is that these conditions result in a mobile window on the scala vestibuli side
of the cochlear partition.
explanation: >-
This landmark paper establishes the third window mechanism as the cause of
the conductive hearing loss pattern seen in SCDS.
downstream:
- target: Abnormal Sound and Pressure Transmission
description: >-
The low-impedance third window allows sound and pressure energy to aberrantly
stimulate vestibular end-organs.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes
explanation: >-
Review synthesis links third-window mechanics to abnormal sound- and pressure-evoked
vestibular stimulation.
- target: Conductive Hearing Loss
description: >-
Acoustic energy is shunted away from the cochlea through the dehiscence,
worsening air conduction while enhancing bone conduction.
evidence:
- reference: PMID:18223508
reference_title: "Conductive hearing loss caused by third-window lesions of the inner ear."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
The CHL results by the dual mechanism of worsening of air conduction thresholds
and improvement of bone conduction thresholds.
explanation: >-
Directly supports the third-window hearing mechanism with reduced air conduction
and enhanced bone conduction.
- target: Autophony
description: >-
Enhanced bone conduction through the third window amplifies perception of
body-generated sounds including voice, breathing, and heartbeat.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
and auditory indications such as autophony, hyperacusis for bone-conducted sounds,
conductive hearing loss, and tinnitus.
explanation: >-
Review describes autophony among characteristic third-window auditory manifestations.
- target: Hyperacusis
description: >-
Increased sensitivity to bone-conducted sounds due to the low-impedance
third window pathway.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
and auditory indications such as autophony, hyperacusis for bone-conducted sounds,
conductive hearing loss, and tinnitus.
explanation: >-
Same review supports hyperacusis as part of the third-window auditory phenotype cluster.
- target: Pulsatile Tinnitus
description: >-
Intracranial vascular pulsations are transmitted to the cochlea via the
third window.
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
The patient developed bilateral aural fullness, pulsatile tinnitus, and
difficulty tolerating loud noises after minor head trauma at 53 years of age.
explanation: >-
Case-level evidence supports pulsatile tinnitus in SCDS; specific fluid-mechanics
mediation is inferred.
- name: Abnormal Sound and Pressure Transmission
description: >-
Sounds and pressure changes that normally would not affect the vestibular system
can now stimulate the superior semicircular canal, leading to vestibular symptoms
triggered by loud sounds (Tullio phenomenon) or pressure changes (Hennebert sign).
Sound energy diverted toward the dehiscence generates pressure differences across
the membranous vestibular labyrinth that excite traveling waves.
cell_types:
- preferred_term: vestibular hair cell
term:
id: CL:0000609
label: vestibular hair cell
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Third window syndrome describes a set of vestibular and auditory symptoms that
arise when a pathological third mobile window is present in the bony labyrinth
of the inner ear.
explanation: >-
The biomechanics review explains how the third window allows sound and pressure
to inappropriately stimulate vestibular structures.
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
For the 60 patients with vestibular manifestations, symptoms induced by loud
sounds were noted in 54 patients and pressure-induced symptoms (coughing,
sneezing, straining) were present in 44.
explanation: >-
Clinical data from the original case series demonstrates the high frequency
of sound- and pressure-induced symptoms in SCDS patients.
downstream:
- target: Vertigo
description: >-
Sound and pressure inappropriately deflect the cupula of the superior
semicircular canal, triggering vestibular responses.
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
For the 60 patients with vestibular manifestations, symptoms induced by loud
sounds were noted in 54 patients and pressure-induced symptoms (coughing,
sneezing, straining) were present in 44.
explanation: >-
Large clinical series supports sound- and pressure-evoked vestibular episodes
consistent with vertigo triggers.
- target: Sound-Induced Nystagmus
description: >-
Vestibular stimulation by loud sounds drives the vestibulo-ocular reflex,
producing nystagmus (Tullio phenomenon).
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Sound-evoked vertigo or nystagmus are now termed "Tullio phenomenon," often
exhibited as a symptom of third window syndrome.
explanation: >-
Review directly supports sound-evoked nystagmus as a hallmark manifestation.
- target: Chronic Disequilibrium
description: >-
Persistent low-level vestibular stimulation from ambient sound and pressure
fluctuations causes ongoing imbalance.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes, chronic
disequilibrium, oscillopsia
explanation: >-
Review includes chronic disequilibrium in the vestibular symptom profile of SSCD.
- name: Otic Capsule Bone Biology
description: >-
The otic capsule exhibits unique bone physiology with greatly suppressed remodeling,
maintained at least in part by extremely high local levels of osteoprotegerin (OPG)
secreted by cochlear soft tissue and reaching the surrounding bone via a
lacunocanalicular network. OPG inhibits osteoclastogenesis, preserving the otic
capsule against the bone resorption that affects other skeletal sites. In SCDS,
histopathological examination shows absence of active bone resorption around the
dehiscence, supporting developmental thin-bone predisposition rather than ongoing
active resorption — though loss of OPG-mediated suppression in animal models is
sufficient to produce abnormal otic capsule remodeling and progressive hearing loss,
suggesting a candidate Hit-2 amplification pathway when this protection fails.
cell_types:
- preferred_term: osteoclast
term:
id: CL:0000092
label: osteoclast
- preferred_term: osteoblast
term:
id: CL:0000062
label: osteoblast
biological_processes:
- preferred_term: bone remodeling
term:
id: GO:0046849
label: bone remodeling
modifier: DECREASED
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
No osteoclastic process was evident within the otic capsule bone surrounding
the dehiscence.
explanation: >-
Histopathological examination showed absence of active bone resorption,
supporting developmental thin-bone predisposition rather than active resorption.
- reference: PMID:15630389
reference_title: "Osteoprotegerin in the inner ear may inhibit bone remodeling in the otic capsule."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
OPG, a powerful inhibitor of bone remodeling, was expressed at extremely
high levels within the soft tissue of the cochlea and was present in the
perilymph at very high concentrations.
explanation: >-
Establishes the OPG-rich inner-ear environment that mechanistically
explains the otic capsule's exceptional remodeling suppression.
- reference: PMID:15630389
reference_title: "Osteoprotegerin in the inner ear may inhibit bone remodeling in the otic capsule."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
OPG, a potent inhibitor of osteoclast formation and function, is expressed
at high levels within the inner ear and is secreted into the perilymph and
the surrounding bone and may serve to inhibit active bone remodeling within
the otic capsule
explanation: >-
Author synthesis frames OPG diffusion from cochlear fluid into otic
capsule bone as the molecular basis of the capsule's suppressed remodeling.
- reference: PMID:16467704
reference_title: "Osteoprotegrin knockout mice demonstrate abnormal remodeling of the otic capsule and progressive hearing loss."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Osteoprotegerin knockout mice demonstrated abnormal remodeling of bone
within the otic capsule with multiple foci showing osteoclastic bone
resorption and formation of new bone.
explanation: >-
Loss-of-function model demonstrates that without OPG-mediated suppression
the otic capsule undergoes pathological remodeling, identifying the
pathway whose failure could contribute to acquired bone erosion.
- reference: PMID:16467704
reference_title: "Osteoprotegrin knockout mice demonstrate abnormal remodeling of the otic capsule and progressive hearing loss."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
The histopathological and pathophysiological findings in OPG knockout
mice support the hypothesis that OPG is important in the inhibition of
bone remodeling within the otic capsule
explanation: >-
Authors directly conclude OPG is required to maintain otic capsule bone
integrity, providing the mechanistic basis for the OPG/RANKL pathway as
a candidate modifier in human otic capsule disorders.
downstream:
- target: Bony Dehiscence of Semicircular Canal
description: >-
Congenitally thin or underdeveloped otic capsule bone provides the structural
substrate for subsequent dehiscence formation.
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The findings were consistent with the hypothesis put forth by Carey and colleagues
that SCD may arise from a failure of postnatal bone development, and that
minor trauma may disrupt thin bone or stable dura over the superior canal.
explanation: >-
Histopathology-based conclusion supports developmental thin-bone predisposition
contributing to dehiscence formation.
phenotypes:
- category: Vestibular
name: Vertigo
frequency: VERY_FREQUENT
description: >-
Episodic vertigo triggered by loud sounds or pressure changes such as coughing,
sneezing, or straining.
phenotype_term:
preferred_term: Vertigo
term:
id: HP:0002321
label: Vertigo
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
For the 60 patients with vestibular manifestations, symptoms induced by loud
sounds were noted in 54 patients and pressure-induced symptoms (coughing,
sneezing, straining) were present in 44.
explanation: >-
The original clinical series demonstrates that the vast majority of SCDS
patients experience sound- or pressure-induced vestibular symptoms.
sequelae:
- target: Chronic Disequilibrium
description: >-
Recurrent vertigo episodes contribute to persistent sensation of imbalance.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: PARTIAL
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes, chronic
disequilibrium, oscillopsia
explanation: >-
Source supports coexistence of vertigo/dizziness and chronic disequilibrium;
directional progression is plausible but not directly tested.
- category: Vestibular
name: Sound-Induced Nystagmus
frequency: VERY_FREQUENT
description: >-
Vestibular symptoms including eye movements (nystagmus) induced by loud sounds,
also known as Tullio phenomenon.
phenotype_term:
preferred_term: Nystagmus
term:
id: HP:0000639
label: Nystagmus
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Sound-evoked vertigo or nystagmus are now termed "Tullio phenomenon," often
exhibited as a symptom of third window syndrome.
explanation: >-
The biomechanics review confirms that sound-evoked nystagmus (Tullio phenomenon)
is a characteristic feature of third window syndrome.
sequelae:
- target: Oscillopsia
description: >-
Involuntary eye movements driven by vestibular stimulation cause perception
of visual oscillation.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: PARTIAL
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes, chronic
disequilibrium, oscillopsia
explanation: >-
Review supports linkage between vestibular eye-movement symptoms and oscillopsia,
though edge-level causality is inferential.
- category: Vestibular
name: Oscillopsia
frequency: FREQUENT
description: >-
Visual disturbance in which objects appear to oscillate, particularly during
movement or exposure to triggering stimuli.
phenotype_term:
preferred_term: Oscillopsia
term:
id: HP:0034773
label: Oscillopsia
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes, chronic
disequilibrium, oscillopsia
explanation: >-
Oscillopsia is listed as one of the vestibular symptoms in SCDS.
- category: Auditory
name: Autophony
frequency: VERY_FREQUENT
description: >-
Abnormally loud perception of one's own voice, breathing, heartbeat, or eye
movements due to enhanced bone conduction.
phenotype_term:
preferred_term: Autophony
term:
id: HP:6000032
label: Autophony
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
and auditory indications such as autophony, hyperacusis for bone-conducted sounds,
conductive hearing loss, and tinnitus.
explanation: >-
Autophony is described as a characteristic auditory symptom of SCDS.
- category: Auditory
name: Pulsatile Tinnitus
frequency: FREQUENT
description: >-
Perception of rhythmic sounds synchronous with the heartbeat.
phenotype_term:
preferred_term: Pulsatile tinnitus
term:
id: HP:0008629
label: Pulsatile tinnitus
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The patient developed bilateral aural fullness, pulsatile tinnitus, and
difficulty tolerating loud noises after minor head trauma at 53 years of age.
explanation: >-
Pulsatile tinnitus is documented as a presenting symptom in this SCDS case.
- category: Auditory
name: Conductive Hearing Loss
frequency: FREQUENT
description: >-
Low-frequency conductive hearing loss due to shunting of acoustic energy through
the dehiscence rather than to the cochlea. Characterized by air-bone gap with
sometimes supranormal bone conduction thresholds.
phenotype_term:
preferred_term: Conductive hearing impairment
term:
id: HP:0000405
label: Conductive hearing impairment
evidence:
- reference: PMID:18223508
reference_title: "Conductive hearing loss caused by third-window lesions of the inner ear."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
The CHL results by the dual mechanism of worsening of air conduction thresholds
and improvement of bone conduction thresholds.
explanation: >-
This landmark paper explains the mechanism of pseudoconductive hearing loss
in third window lesions.
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
An air-bone on audiometry in these patients with vestibular manifestations
measured (mean +/- SD) 19 +/- 14 dB at 250 Hz; 15 +/- 11 dB at 500 Hz;
11 +/- 9 dB at 1,000 Hz; and 4 +/- 6 dB at 2,000 Hz.
explanation: >-
Clinical data demonstrates the characteristic low-frequency air-bone gap
pattern in SCDS patients.
- category: Vestibular
name: Chronic Disequilibrium
frequency: FREQUENT
description: >-
Persistent sensation of imbalance or unsteadiness.
phenotype_term:
preferred_term: Gait imbalance
term:
id: HP:0002141
label: Gait imbalance
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Symptoms include vestibular indications such as eye movements or dizziness
evoked by sound or middle ear/intracranial pressure changes, chronic
disequilibrium, oscillopsia
explanation: >-
Chronic disequilibrium is listed as one of the vestibular symptoms in SCDS.
- category: Auditory
name: Hyperacusis
frequency: OCCASIONAL
description: >-
Increased sensitivity to bone-conducted sounds.
phenotype_term:
preferred_term: Hyperacusis
term:
id: HP:0010780
label: Hyperacusis
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
and auditory indications such as autophony, hyperacusis for bone-conducted sounds,
conductive hearing loss, and tinnitus.
explanation: >-
Hyperacusis is listed as an auditory symptom of SCDS.
biochemical:
- name: Serum Adjusted Calcium
presence: DECREASED
context: >-
A small case-control study found a statistically significantly lower
serum adjusted calcium level in SCDS patients compared to age- and
sex-matched controls (2.34 vs 2.41 mmol/L, p = 0.01), though both
values fell within the normal reference range. The authors interpret
this as a possible signal that suboptimal calcium availability may
affect the otic capsule micro-environment, but the clinical
significance is uncertain given that values remained within normal
limits.
biomarker_term:
preferred_term: serum adjusted calcium
term:
id: CHEBI:29108
label: calcium(2+)
evidence:
- reference: PMID:36820155
reference_title: "Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case control study."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
Mean Adjusted calcium level was 2.34 mmoL/l (SD: 0.7) for SSCD compared
to 2.41 mmoL/l (SD: 0.11) for controls (p = 0.01), being within normal
limits for both the SSCD and the control group.
explanation: >-
Documents a small but statistically significant lower adjusted calcium
in SCDS, with both groups within the normal reference range.
- name: Serum 25-hydroxyvitamin D
presence: NORMAL
context: >-
Vitamin D status was investigated as a candidate biochemical
contributor to otic capsule bone integrity, but no significant
difference was found between SCDS patients and controls (44.8 vs
47.5 nmol/L, p = 0.702). This finding refutes the hypothesis that
vitamin D deficiency is a meaningful predisposing factor in SCDS.
biomarker_term:
preferred_term: serum 25-hydroxyvitamin D
term:
id: CHEBI:17933
label: calcidiol
evidence:
- reference: PMID:36820155
reference_title: "Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case control study."
supports: REFUTE
evidence_source: HUMAN_CLINICAL
snippet: >-
Our study did not identify a link between Vitamin D levels and presence
of SSCD.
explanation: >-
Authors directly conclude no association between vitamin D and SCDS,
refuting the candidate-biomarker hypothesis.
genetic:
- name: CDH23
gene_term:
preferred_term: CDH23
term:
id: hgnc:13733
label: CDH23
association: Risk Factor
notes: >-
CDH23 encodes cadherin-23, a tip-link protein required for inner ear hair-cell
stereocilia function; biallelic pathogenic variants cause Usher syndrome type 1D
and DFNB12. Beyond stereocilia, CDH23 variants are associated with semicircular
canal abnormalities in pediatric carriers, suggesting a role in otic capsule
development. The strongest single-gene SCDS association reported to date.
evidence:
- reference: PMID:27631835
reference_title: "CDH23 Related Hearing Loss: A New Genetic Risk Factor for Semicircular Canal Dehiscence?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Eighty-six percent of the CDH23 variant group had abnormalities in at least
one canal compared with only 12% in age-matched controls.
explanation: >-
Pediatric cohort comparison establishes a high-penetrance association
between CDH23 pathogenic variants and semicircular canal abnormalities.
- reference: PMID:27631835
reference_title: "CDH23 Related Hearing Loss: A New Genetic Risk Factor for Semicircular Canal Dehiscence?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In the CDH23 variant group there were four patients with superior SCD
(57%, RR = 10.0) and three patients with posterior canal abnormalities
(43%, RR = 7.5)
explanation: >-
Quantifies the canal-specific relative risks for superior and posterior
SCD in CDH23 variant carriers.
- reference: PMID:27631835
reference_title: "CDH23 Related Hearing Loss: A New Genetic Risk Factor for Semicircular Canal Dehiscence?"
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Children with a CDH23 pathogenic variants are at significantly increased
risk of having SCD and this may be a contributing factor to the vestibular
dysfunction in Usher syndrome type 1D patient population.
explanation: >-
Authors directly conclude CDH23 pathogenic variants are a genetic risk
factor for SCD and a contributor to Usher 1D vestibular phenotype.
- name: NOTCH2
gene_term:
preferred_term: NOTCH2
term:
id: hgnc:7882
label: NOTCH2
association: Risk Factor
notes: >-
Gain-of-function mutations in NOTCH2 (typically truncating mutations in exon 34)
cause Hajdu-Cheney syndrome, characterized by acro-osteolysis, severe osseous
demineralization, and hearing loss with otic capsule involvement. NOTCH2 enhances
osteoclast differentiation and bone resorption, providing a candidate "Hit 2"
mechanism for accelerated erosion of already-thin SSC bone.
evidence:
- reference: PMID:41326232
reference_title: "Temporal Bone CT Findings in Hajdu-Cheney Syndrome: Case Report with Review of the Literature."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The syndrome is caused by gain-of-function mutations in the NOTCH2 gene,
which disrupt bone remodeling and connective tissue integrity.
explanation: >-
Establishes the gain-of-function NOTCH2 mechanism and its impact on bone
remodeling, the molecular basis for Hajdu-Cheney's otic capsule phenotype.
- reference: PMID:41326232
reference_title: "Temporal Bone CT Findings in Hajdu-Cheney Syndrome: Case Report with Review of the Literature."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
relatively symmetric, diffuse osseous demineralization of the temporal
bones, with ossicular and otic capsule involvement.
explanation: >-
Documents temporal bone and otic capsule demineralization in a NOTCH2
gain-of-function patient, the human imaging correlate of the proposed
bone-erosion pathway.
- reference: PMID:32143606
reference_title: "Distinct severity of phenotype in Hajdu-Cheney syndrome: a case report and literature review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Hajdu-Cheney syndrome (HCS) is a rare inherited skeletal disorder caused
by pathogenic mutations in exon 34 of NOTCH2.
explanation: >-
Localizes the disease-causing NOTCH2 mutations to exon 34, the
gain-of-function hotspot relevant to the bone-resorption phenotype.
- reference: PMID:32526405
reference_title: "Notch and the regulation of osteoclast differentiation and function."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
NOTCH1 inhibits osteoclastogenesis, whereas NOTCH2 enhances osteoclast
differentiation and function by direct and indirect mechanisms.
explanation: >-
Mechanistic review establishes NOTCH2 as an osteoclastogenesis enhancer,
consistent with bone-erosion-mediated otic capsule thinning.
- name: EDS-Related Connective Tissue Disorder
association: Risk Factor
notes: >-
Reported SSCD-Ehlers-Danlos cases have been hypermobility-type EDS (hEDS),
whose genetic basis is heterogeneous and largely unmapped — most cases are
not attributable to a single confirmed gene. The classical-EDS collagen
genes (COL5A1, COL3A1, COL1A1) are mechanistically plausible candidates
via shared collagen-matrix disruption, but no specific gene has been
confirmed in SCDS-associated EDS cohorts. This entry is therefore curated
as a connective-tissue-disorder risk class rather than a single-gene
driver. Bilateral SSCD has been the consistent presenting pattern,
suggesting a systemic collagen-matrix mechanism rather than a focal lesion.
evidence:
- reference: PMID:28484680
reference_title: "Superior Semicircular Canal Dehiscence in a Patient with Ehlers-Danlos Syndrome: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Ehlers-Danlos syndrome (EDS) constitutes a group of genetic connective
tissue disorders caused by a defect in the production, processing, or
structure of collagen, or its associated proteins.
explanation: >-
Establishes the collagen-pathway pathophysiology that links EDS to
systemic connective-tissue weakness including temporal bone matrix.
- reference: PMID:28484680
reference_title: "Superior Semicircular Canal Dehiscence in a Patient with Ehlers-Danlos Syndrome: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The patient was subsequently diagnosed with bilateral SSCD and underwent
a right middle fossa (pre-auricular infratemporal) craniotomy for SSCD
repair.
explanation: >-
First reported case of bilateral SSCD in an EDS-hypermobility patient,
consistent with a systemic connective-tissue contribution.
- reference: PMID:30385359
reference_title: "Bilateral Superior Semicircular Canal Dehiscence Associated with Ehlers-Danlos Syndrome: A Report of 2 Cases."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients with EDS are more likely to have bony abnormalities, which may
predispose them to developing SSCD.
explanation: >-
Two-case series reinforces the EDS-SSCD predisposition hypothesis through
collagen-mediated bony abnormalities.
- reference: PMID:30385359
reference_title: "Bilateral Superior Semicircular Canal Dehiscence Associated with Ehlers-Danlos Syndrome: A Report of 2 Cases."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Both patients presented with bilateral auditory and vestibular symptoms,
and computed tomography scan confirmed the presence of bilateral
dehiscence in their superior semicircular canals.
explanation: >-
Confirms bilateral presentation across additional EDS-HT cases,
supporting a systemic connective-tissue mechanism.
- name: Trisomy 21
association: Risk Factor
inheritance:
- name: Sporadic
features: >-
Down syndrome (trisomy of chromosome 21) is associated with global inner
ear dysplasia, including a substantially elevated rate of semicircular
canal dehiscence. The mechanism is presumed to be aneuploidy-driven
disruption of inner ear morphogenesis rather than a focused single-gene
effect.
evidence:
- reference: PMID:22936282
reference_title: "Inner ear anomalies seen on CT images in people with Down syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Inner ear anomalies were observed in 74.5% (38/51) of patients.
explanation: >-
Quantifies the very high background rate of inner ear malformations in
Down syndrome that contextualizes the SSCD finding.
- reference: PMID:22936282
reference_title: "Inner ear anomalies seen on CT images in people with Down syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
semicircular canal dehiscence (SCCD), and enlarged vestibular aqueducts
were detected in 52.5% (53/101), 24.5% (25/102), 21.4% (21/98), 8.8%
(9/102) and 2% (2/101) of patients' ears, respectively.
explanation: >-
Documents an 8.8% per-ear SCCD rate in trisomy 21 patients, several-fold
above the general-population radiographic prevalence.
- name: Cat Eye Syndrome (chr22 duplication)
association: Risk Factor
inheritance:
- name: Sporadic
features: >-
Cat eye syndrome arises from duplication of chromosome 22 (typically
creating a small supernumerary marker chromosome); inner ear dysmorphology
has been linked to posterior semicircular canal dehiscence (PSCD) in at
least one reported case. The reported case is PSCD rather than SSCD, but
is included here under the broader semicircular canal dehiscence syndrome
scope as evidence for a chromosomal-aneuploidy class of dehiscence
predisposition. Listed as a representative chromosomal aneuploidy rather
than a single recurrent mechanism.
evidence:
- reference: PMID:31804144
reference_title: "Rare otologic presentation of cat eye syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
We encountered an extremely rare case where a patient with cat eye
syndrome (CES) who presented with symptoms of posterior semicircular
canal dehiscence (PSCD).
explanation: >-
First reported association of CES with posterior canal dehiscence,
supporting a chromosomal-aneuploidy class of SCDS predisposition.
- reference: PMID:31804144
reference_title: "Rare otologic presentation of cat eye syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
CES is a rare genetic disorder, resulting from duplication of chromosome
22.
explanation: >-
Establishes the underlying chromosome-22 duplication mechanism for the
CES-SCDS association.
environmental:
- name: Minor Head Trauma
presence: Triggering
exposure_term:
preferred_term: head trauma
term:
id: ECTO:0010003
label: exposure to environmental physical object quality
description: >-
Minor head trauma may precipitate symptom onset in anatomically predisposed
individuals with thin superior canal bone.
effect: Can trigger clinical decompensation of previously compensated dehiscence.
evidence:
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The patient developed bilateral aural fullness, pulsatile tinnitus, and
difficulty tolerating loud noises after minor head trauma at 53 years of age.
explanation: >-
Case-level evidence supports minor head trauma as a precipitating trigger
for symptomatic SCDS.
- reference: PMID:22312921
reference_title: "Histopathology of the temporal bone in a case of superior canal dehiscence syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The findings were consistent with the hypothesis put forth by Carey and colleagues
that SCD may arise from a failure of postnatal bone development, and that
minor trauma may disrupt thin bone or stable dura over the superior canal.
explanation: >-
Histopathology paper explicitly supports developmental predisposition with
trauma-triggered symptom emergence.
- reference: PMID:30928582
reference_title: "Clinical Assessment of Patients with Bilateral Superior Semicircular Canal Dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Previous trauma to the head correlated with a bilateral SSCD presentation
(P = 0.04).
explanation: >-
Cohort-level evidence that head trauma is specifically associated with
bilateral SSCD presentation, consistent with trauma converting pre-existing
bilateral thin bone into bilateral dehiscence.
- reference: PMID:41063339
reference_title: "Risk Factors and Preceding Events Predisposing the Development of Superior Canal Dehiscence Syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
external trauma (eg, fall, motor vehicle accident, etc) in 32%
explanation: >-
Largest SCDS surgical cohort to date documents external trauma as a
precipitating event in roughly one-third of patients with identified triggers.
- name: Loud Sound and Pressure Changes
presence: Triggering
exposure_term:
preferred_term: loud sound exposure
term:
id: ECTO:8000044
label: exposure to sound radiation
description: >-
Loud sounds and pressure maneuvers (coughing, sneezing, straining, Valsalva)
frequently provoke vestibular symptoms in patients with established
dehiscence and may also serve as precipitating events for symptom onset
by acutely fracturing or disrupting pre-thinned bone. In the largest
surgical cohort to date, internal Valsalva-type events were the most
common identified preceding event among patients reporting a clear
trigger. The exposure_term is bound to sound radiation; the pressure
component is not separately ontology-bound (no clean ECTO term for
Valsalva-type acute pressure events).
effect: Triggers vertigo, nystagmus, and dizziness episodes; can precipitate symptom onset.
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
For the 60 patients with vestibular manifestations, symptoms induced by loud
sounds were noted in 54 patients and pressure-induced symptoms (coughing,
sneezing, straining) were present in 44.
explanation: >-
Large clinical cohort demonstrates that sound and pressure triggers are common
provoking factors in SCDS.
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Patients with mild symptoms can reduce exposure to loud sounds and avoid
physical straining, and those with pressure sensitivity can benefit from
a tympanostomy tube
explanation: >-
Review guidance reinforces clinical relevance of these trigger exposures in
day-to-day symptom control.
- reference: PMID:41063339
reference_title: "Risk Factors and Preceding Events Predisposing the Development of Superior Canal Dehiscence Syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
One hundred seventy-five (43%) patients described preceding events
leading to the development of symptoms
explanation: >-
Documents that 43% of SCDS surgical patients can identify a discrete
precipitating event, supporting an acquired second-hit mechanism.
- reference: PMID:41063339
reference_title: "Risk Factors and Preceding Events Predisposing the Development of Superior Canal Dehiscence Syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
internal cause (eg, sneezing or coughing, etc) in 33% of those patients
explanation: >-
Internal Valsalva-type pressure events are the leading reported
precipitating trigger among patients with an identifiable inciting event.
- name: Chronic Occupational Noise and Pressure Exposure
presence: Predisposing
exposure_term:
preferred_term: chronic occupational noise exposure
term:
id: ECTO:8000044
label: exposure to sound radiation
description: >-
Repeated occupational exposure to loud noise and ambient pressure changes
is reported by a substantial fraction of SCDS patients and is hypothesized
to contribute to chronic micro-injury of thin SSC bone, accelerating the
transition from thinning to dehiscence.
effect: >-
May accelerate bone erosion in predisposed individuals through chronic
pressure and acoustic loading.
evidence:
- reference: PMID:41063339
reference_title: "Risk Factors and Preceding Events Predisposing the Development of Superior Canal Dehiscence Syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Of those with a reported occupation (n=207), occupational exposures
included loud noises in 22% and ambient pressure changes in 23% of
patients.
explanation: >-
Quantifies the prevalence of chronic occupational noise and pressure
exposure in a large SCDS surgical cohort.
- reference: PMID:41063339
reference_title: "Risk Factors and Preceding Events Predisposing the Development of Superior Canal Dehiscence Syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Certain occupational and avocational factors may predispose individuals
to SCDS, and certain traumatic events may precipitate its development.
explanation: >-
Authors directly conclude that occupational and avocational exposures
are predisposing factors for SCDS.
- name: Elevated Intracranial Pressure / Idiopathic Intracranial Hypertension
presence: Predisposing
description: >-
A possible role for chronically elevated intracranial pressure (ICP),
typified by idiopathic intracranial hypertension (IIH), as a contributor
to SSC bone erosion is contested. Some studies report higher rates of SSC
thinning and dehiscence in IIH patients but no dose-response relationship
between CSF pressure and bone thickness, and other studies find no
association at all. SCDS patients differ from spontaneous CSF-leak
patients in lacking obesity-related risk factors, weakening the analogy.
effect: >-
May contribute to chronic bone erosion in some patients; primary causal
role unestablished.
evidence:
- reference: PMID:34424380
reference_title: "Dehiscence or thinning of bone overlying the superior semicircular canal in idiopathic intracranial hypertension."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
Bony roof thickness was 1.25 mm in the control group and 0.76 mm in the
IIH group.
explanation: >-
IIH patients have measurably thinner SSC bone than controls, supporting
a possible erosive role of elevated ICP.
- reference: PMID:34424380
reference_title: "Dehiscence or thinning of bone overlying the superior semicircular canal in idiopathic intracranial hypertension."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
The correlation between bony roof thickness and cerebrospinal fluid
(CSF) pressure in the IIH group was not statistically significant
(p = 0.343; rho = 0.110).
explanation: >-
The lack of dose-response between CSF pressure and bone thickness
argues against a direct erosive mechanism, suggesting shared
predisposition rather than ICP-mediated causation.
- reference: PMID:28833207
reference_title: "Semicircular canal dehiscence among idiopathic intracranial hypertension patients."
supports: REFUTE
evidence_source: HUMAN_CLINICAL
snippet: >-
None of the 24 patients with IIH had radiographic SSCD, whereas eight
of the 97 patients (8.2%) without IIH had radiographic SSCD.
explanation: >-
Independent cohort failed to find any IIH-SSCD association, directly
refuting the proposed ICP-driven mechanism.
- reference: PMID:28833207
reference_title: "Semicircular canal dehiscence among idiopathic intracranial hypertension patients."
supports: REFUTE
evidence_source: HUMAN_CLINICAL
snippet: >-
The results of this retrospective pilot study do not suggest an
association between IIH and SSCD.
explanation: >-
Authors directly conclude no IIH-SSCD association in their cohort.
- name: Post-Menopausal Estrogen Decline
presence: Modifying
description: >-
Post-menopausal estrogen decline is hypothesized to accelerate otic
capsule bone loss through reduced OPG-mediated suppression of
osteoclastogenesis (see "Otic Capsule Bone Biology" pathophysiology
node). Selective SSC bone thinning has been observed in women over 45,
consistent with menopausal contribution; SCDS surgical cohorts show a
consistent female predominance (~57-66% female across series). However,
cross-sectional CT cohorts have not detected an overall sex difference
in baseline SSC bone thickness, indicating that any hormonal effect is
likely age-restricted rather than constitutive.
effect: >-
May contribute to bone-erosion phase (Hit 2) in older women through
estrogen-OPG-RANKL signaling.
evidence:
- reference: PMID:36573139
reference_title: "Evaluation of Superior Semicircular Canal Morphology and Its Relationship with Glenoid Fossa Roof Thickness Using Cone Beam Computed Tomography."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
However, superior semicircular canal dehiscence (SSCD) was more
prevalent among females over 45 years old.
explanation: >-
Documents an age-restricted female predominance for SSCD, consistent
with a post-menopausal hormonal contribution.
- reference: PMID:36573139
reference_title: "Evaluation of Superior Semicircular Canal Morphology and Its Relationship with Glenoid Fossa Roof Thickness Using Cone Beam Computed Tomography."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Considering the decrease in the thickness of the SSC roof among females
over 45 years of age, menopause may be responsible for this occurrence
as well as for the increase in the prevalence of SSCD.
explanation: >-
Authors directly invoke menopause as a candidate mechanism for the
female-specific SSC thinning seen after age 45.
- reference: PMID:19121641
reference_title: "The effect of sex hormones on bone metabolism of the otic capsule--an overview."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Estrogen contributes to bone protection since it decreases the response
of osteoclasts to RANKL and induces osteoclast apoptosis.
explanation: >-
Mechanistic review establishes the molecular basis (estrogen → OPG/RANKL
→ osteoclast suppression) by which menopausal estrogen decline could
accelerate otic capsule bone loss.
- reference: PMID:31035843
reference_title: "The variation of superior semicircular canal bone thickness in relation to age and gender."
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
There was no significant difference between the female and male bone
thickness (p = .7113).
explanation: >-
Contrasting evidence: cross-sectional cohort finds no overall sex
difference in SSC bone thickness, consistent with any hormonal effect
being age-restricted rather than constitutive.
treatments:
- name: Observation and Symptom Management
description: >-
For mild cases, conservative management including avoidance of triggering stimuli
and vestibular rehabilitation may be sufficient. Patients with pressure sensitivity
can benefit from a tympanostomy tube.
treatment_term:
preferred_term: avoid destabilizing activities
term:
id: MAXO:0000804
label: avoid destabilizing activities
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Patients with mild symptoms can reduce exposure to loud sounds and avoid
physical straining, and those with pressure sensitivity can benefit from
a tympanostomy tube
explanation: >-
Conservative management options are described for patients with mild symptoms.
- name: Middle Fossa Craniotomy with Canal Plugging
description: >-
Surgical occlusion of the dehiscent superior semicircular canal via a
middle cranial fossa craniotomy. The dehiscence is identified through
the temporal lobe approach and the canal lumen is occluded with bone
wax, fascia, or bone pâté to eliminate the third-window effect. This is
the most established surgical option and the procedure of choice in
most centers; canal plugging achieves long-term symptom control more
often than resurfacing.
treatment_term:
preferred_term: middle cranial fossa craniotomy with canal plugging
term:
id: NCIT:C15214
label: Craniotomy
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Canal plugging was performed in 9 and resurfacing of the canal without
plugging of the lumen in 11 patients. Complete resolution of vestibular
symptoms and signs was achieved in 8 of the 9 patients after canal plugging.
explanation: >-
Clinical data demonstrates high success rate of canal plugging via
middle cranial fossa craniotomy.
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Canal plugging achieves long-term control more often than resurfacing and
is usually the procedure of choice
explanation: >-
Canal plugging is established as the preferred surgical treatment.
- name: Middle Fossa Craniotomy with Canal Resurfacing
description: >-
Surgical repair via middle cranial fossa craniotomy in which a bone graft
or other material is placed over the dehiscence to restore normal inner
ear mechanics without occluding the canal lumen. Less reliable than
canal plugging but preserves canal patency.
treatment_term:
preferred_term: middle cranial fossa craniotomy with canal resurfacing
term:
id: NCIT:C15214
label: Craniotomy
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Complete resolution of vestibular symptoms and signs was achieved in 8 of
the 9 patients after canal plugging and in 7 of the 11 patients after
resurfacing.
explanation: >-
Resurfacing can achieve symptom resolution, though less reliably than plugging.
- reference: PMID:36742050
reference_title: "New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
The changes observed also reverse and return to baseline as the SSCD heals
by bone resurfacing (with the lumen intact).
explanation: >-
Animal model demonstrates that bony resurfacing can restore normal function
while preserving canal lumen patency.
- name: Transmastoid Canal Plugging
description: >-
An alternative surgical approach in which the superior semicircular canal
is plugged via a transmastoid mastoidectomy rather than middle cranial
fossa craniotomy. Avoids temporal lobe retraction; reported as safe and
effective with characteristic post-operative VHIT deficits in the SSCC
plane confirming successful plugging.
treatment_term:
preferred_term: transmastoid canal plugging
term:
id: NCIT:C51751
label: Mastoidectomy
evidence:
- reference: PMID:39812476
reference_title: "Transmastoid superior semicircular canal dehiscence plugging: VHIT findings."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Patients having a superior semicircular canal dehiscence (SSCCD) syndrome
with debilitating symptoms who underwent a plugging of the SSCC via a
transmastoid approach were included.
explanation: >-
Defines the transmastoid plugging cohort and intervention.
- reference: PMID:39812476
reference_title: "Transmastoid superior semicircular canal dehiscence plugging: VHIT findings."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Almost all patients had improvement of their preoperative symptoms. No
surgical complication was noted. The literature review also highlighted
safety and effectiveness of this surgical technique.
explanation: >-
Documents symptomatic improvement and safety of the transmastoid
approach as an alternative to middle fossa craniotomy.
- name: Round Window Reinforcement
description: >-
Transcanal/middle-ear surgical option in which the round window niche is
reinforced (e.g., with fascia, perichondrium, or cartilage) to alter the
impedance of the third-window pathway without addressing the dehiscent
canal directly. Less established than canal plugging or resurfacing,
used selectively for patients with intractable symptoms.
treatment_term:
preferred_term: round window reinforcement
term:
id: NCIT:C15329
label: Surgical Procedure
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
As an alternative to canal plugging, round window reinforcement has been
shown to reduce most symptoms in most patients with intractable superior
semicircular canal dehiscence with the exception of hearing loss
explanation: >-
Establishes round window reinforcement as a documented alternative
surgical option for SCDS, with caveat about residual hearing loss.
diagnosis:
- name: High-Resolution CT Temporal Bone
description: >-
Thin-slice CT imaging of the temporal bone in multiple planes to visualize
the bony defect over the superior semicircular canal. While imaging is
important, false positives occur, motivating the use of physiological
indicators prior to CT imaging.
diagnosis_term:
preferred_term: high-resolution temporal bone computed tomography
term:
id: NCIT:C17204
label: Computed Tomography
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
High-resolution computed-tomography images of the temporal bone revealed
dehiscence of the bone above the superior semicircular canal, and imaging
was considered the gold standard for diagnosis for a number of years.
explanation: >-
CT imaging is essential for visualizing the dehiscence.
- name: Vestibular Evoked Myogenic Potentials (VEMP)
description: >-
Cervical and ocular VEMP testing shows reduced thresholds and increased
amplitudes characteristic of third window lesions. Thresholds normalize
after surgical repair.
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The threshold for eliciting vestibular-evoked myogenic potentials from
affected ears was (mean +/- SD) 81 +/- 9 dB normal hearing level. The
threshold for unaffected ears was 99 +/- 7 dB, and the threshold for
control ears was 98 +/- 4 dB.
explanation: >-
Clinical data demonstrates significantly reduced VEMP thresholds in
affected ears compared to unaffected and control ears.
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Vestibular Evoked Myogenic Potentials (VEMPs) provide a strong diagnostic
indicator of SSCD.
explanation: >-
VEMPs are established as a strong diagnostic indicator for SCDS.
- name: Audiometry
description: >-
May reveal characteristic low-frequency air-bone gap with normal bone
conduction or supranormal bone conduction thresholds, without middle ear
pathology. The air-bone gap is largest at low frequencies and diminishes
above 2000 Hz.
diagnosis_term:
preferred_term: audiometric test
term:
id: NCIT:C38036
label: Audiometric Test
evidence:
- reference: PMID:18223508
reference_title: "Conductive hearing loss caused by third-window lesions of the inner ear."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Clues to suspect such a lesion include a low-frequency air-bone gap with
supranormal thresholds for bone conduction, and presence of acoustic
reflexes, vestibular evoked myogenic responses, or otoacoustic emission
responses despite the CHL.
explanation: >-
The audiometric pattern of low-frequency air-bone gap with supranormal
bone conduction is characteristic of third window lesions.
differential_diagnoses:
- name: Meniere Disease
disease_term:
preferred_term: Meniere disease
term:
id: MONDO:0007972
label: Meniere disease
description: >-
Inner-ear disorder with overlapping episodic vertigo, tinnitus, and aural
symptoms that can mimic SCDS.
distinguishing_features:
- SCDS more often has sound- and pressure-evoked symptoms (Tullio/Hennebert phenomena).
- Physiologic third-window findings (low-threshold VEMP, low-frequency air-bone gap with intact middle ear) favor SCDS.
- CT evidence of superior canal dehiscence supports SCDS rather than Meniere disease.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Since these studies, various causes of the Tullio phenomenon and Hennebert's
sign have been reported, such as perilymphatic fistula (9, 10), Ménière's
disease (11), and cholesteatoma (12).
explanation: >-
Review explicitly identifies Ménière's disease as a competing cause of similar
vestibular signs.
- name: Cholesteatoma
disease_term:
preferred_term: cholesteatoma
term:
id: MONDO:0006530
label: cholesteatoma
description: >-
Middle-ear disease that can produce pressure/sound-related vestibular findings
and auditory complaints overlapping with SCDS.
distinguishing_features:
- Structural middle-ear pathology on otologic exam/imaging favors cholesteatoma.
- Third-window physiology and superior canal bony defect support SCDS.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: SUPPORT
evidence_source: OTHER
snippet: >-
Since these studies, various causes of the Tullio phenomenon and Hennebert's
sign have been reported, such as perilymphatic fistula (9, 10), Ménière's
disease (11), and cholesteatoma (12).
explanation: >-
Same review explicitly includes cholesteatoma among key differential etiologies
of similar vestibular signs.
- name: Otosclerosis
disease_term:
preferred_term: otosclerosis
term:
id: MONDO:0005349
label: otosclerosis
description: >-
Common differential diagnosis for conductive hearing loss with an intact
tympanic membrane and may be mistaken for third-window hearing findings.
distinguishing_features:
- SCDS may show supranormal bone conduction and abnormal VEMP responses despite air-bone gap.
- Presence of vestibular sound/pressure triggers and CT-proven dehiscence supports SCDS.
evidence:
- reference: PMID:18223508
reference_title: "Conductive hearing loss caused by third-window lesions of the inner ear."
supports: PARTIAL
evidence_source: OTHER
snippet: >-
Third-window lesions should be considered in the differential diagnosis of CHL
in patients with an intact tympanic membrane and an aerated, otherwise healthy,
middle ear.
explanation: >-
Review highlights the need to distinguish third-window CHL (including SCDS)
from classic middle-ear conductive hearing disorders such as otosclerosis.
- name: Benign Paroxysmal Positional Vertigo
disease_term:
preferred_term: benign paroxysmal positional vertigo
term:
id: MONDO:8000018
label: benign paroxysmal positional vertigo
description: >-
Positional vertigo syndrome that overlaps symptomatically with vestibular
complaints in SCDS and may coexist in postoperative contexts.
distinguishing_features:
- BPPV is position-triggered without defining third-window auditory features.
- SCDS is characterized by sound/pressure-triggered vestibular symptoms plus third-window audiovestibular test abnormalities.
evidence:
- reference: PMID:32982922
reference_title: "Biomechanics of Third Window Syndrome."
supports: PARTIAL
evidence_source: OTHER
snippet: >-
New-onset benign paroxysmal positional vertigo has been reported in up to 25%
of postoperative patients likely due to otoconia or plugging material that
becomes mobilized in the endolymph (101).
explanation: >-
Review documents clinically relevant BPPV overlap/co-occurrence in SCDS care,
supporting its inclusion in differential consideration.
datasets:
- accession: PMID:16222184
title: Clinical manifestations of superior semicircular canal dehiscence
description: >-
Clinical cohort dataset from 65 SCDS patients including symptom triggers,
audiometric air-bone gaps, VEMP thresholds, and postsurgical outcomes for
canal plugging versus resurfacing.
organism:
preferred_term: Homo sapiens
term:
id: NCBITaxon:9606
label: Homo sapiens
sample_types:
- preferred_term: superior semicircular canal
term:
id: UBERON:0001841
label: anterior semicircular canal
sample_count: 65
conditions:
- vestibular manifestations
- exclusively auditory manifestations
notes: Clinical cohort summary dataset derived from published audiovestibular phenotyping; not a GA4GH Phenopacket resource.
publication: PMID:16222184
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
There were 65 patients who qualified for inclusion in this study on the basis
of these criteria.
explanation: >-
Defines the cohort size and supports this publication as a reusable clinical
phenotype dataset for SCDS.
findings:
- statement: >-
Most patients had sound- and pressure-triggered vestibular symptoms with
objective low-frequency air-bone gaps and reduced VEMP thresholds.
evidence:
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
For the 60 patients with vestibular manifestations, symptoms induced by loud
sounds were noted in 54 patients and pressure-induced symptoms (coughing,
sneezing, straining) were present in 44.
explanation: >-
Documents high prevalence of sound/pressure-triggered vestibular symptoms
in the cohort.
- reference: PMID:16222184
reference_title: "Clinical manifestations of superior semicircular canal dehiscence."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
The threshold for eliciting vestibular-evoked myogenic potentials from affected
ears was (mean +/- SD) 81 +/- 9 dB normal hearing level.
explanation: >-
Provides objective physiological measurements characteristic of SCDS.
- accession: PMID:36742050
title: New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder
description: >-
Experimental gerbil SSCD dataset with longitudinal ABR and c+VEMP measurements
following superior semicircular canal fenestration, including recovery dynamics
during spontaneous bone resurfacing.
organism:
preferred_term: Meriones unguiculatus
term:
id: NCBITaxon:10047
label: Meriones unguiculatus
sample_types:
- preferred_term: superior semicircular canal
term:
id: UBERON:0001841
label: anterior semicircular canal
sample_count: 36
conditions:
- small 1 mm superior semicircular canal dehiscence
- large 2 mm superior semicircular canal dehiscence
- post-fenestration recovery with bone resurfacing
notes: Experimental physiology dataset (ABR/c+VEMP and micro-CT) extracted from publication; not a GA4GH Phenopacket resource.
publication: PMID:36742050
evidence:
- reference: PMID:36742050
reference_title: "New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
Adult Mongolian gerbils (n = 36) received surgical fenestration of the superior
semicircular canal of the left inner ear.
explanation: >-
Defines the model-organism cohort and intervention used to generate the dataset.
findings:
- statement: >-
Experimental SSCD caused low-frequency hearing threshold worsening and enhanced
cVEMP responses that normalized as the bony defect resurfaced.
evidence:
- reference: PMID:36742050
reference_title: "New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
The SSCD created a significant worsening of hearing thresholds of the left ear;
especially in the lower frequency domain (1-4 kHz).
explanation: >-
Demonstrates pseudoconductive hearing phenotype in the model.
- reference: PMID:36742050
reference_title: "New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder."
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
As the bone regrew, the c+VEMP and ABR responses returned toward preoperative
values.
explanation: >-
Supports reversibility of physiological abnormalities with spontaneous resurfacing.
notes: >-
Superior semicircular canal dehiscence syndrome was first described by Lloyd
Minor and colleagues in 1998. The condition is also known as Minor syndrome.
A cadaveric survey of 1,000 temporal bones found 0.5% had complete dehiscence
and another 1.4% had significant thinning of bone overlying the superior canal,
though clinical presentation of symptoms is less common than anatomic prevalence
suggests. Radiographic adult prevalence on temporal bone CT (3.6-11%) exceeds
cadaveric prevalence, reflecting CT resolution limits and the inclusion of
thin-but-not-dehiscent bone.
The current synthesis favors a two-hit model: (1) a developmental "Hit 1" of
incomplete postnatal otic capsule ossification, leaving a stable adult
population (~11% of individuals) with persistent thin SSC bone; followed by
(2) an acquired "Hit 2" of age-related remodeling, mechanical trauma,
Valsalva-type pressure events, or chronic noise/pressure exposure that
converts thin bone into frank dehiscence. The model is supported by the
age-dissociation between thinning prevalence (stable across age groups) and
dehiscence prevalence (rising ~93% per age category), the generalized rather
than focal nature of skull base thinning in SSCD, and the systemic
bilateral pattern of bone thinning.
Surgical SCDS cohorts consistently show a moderate female predominance
(Wei 2026: 57% female of n=405; Chen 2019: 65.9% female among bilateral
cases). The mechanism is uncertain: cross-sectional CT cohorts do not
detect an overall sex difference in baseline SSC bone thickness, but
selective SSC thinning has been reported in women over 45, suggesting a
post-menopausal modifier rather than a constitutive sex difference. The
estrogen → OPG/RANKL → osteoclast pathway provides a candidate molecular
link.
Candidate developmental genes from animal models and adjacent clinical
genetics have not been tested in human SCDS cohorts and are therefore not
curated as `genetic` drivers here. DLX5 null mice show severe vestibular
organ malformations, delayed skull-roof ossification, and abnormal
osteogenesis (PMID:10433909); HOXA1 disruption affects skull ossification
and inner ear development; NOG variants cause congenital stapes fixation
with cochlear and vestibular dysplasia in some patients (PMID:39837070).
Each is plausibly relevant to the developmental thin-bone substrate but
awaits direct testing in SCDS populations. No genome-wide association
study for SCDS has been published; the common variants underlying the ~11%
adult predisposition rate remain unknown.
references:
- reference: DOI:10.1016/j.joto.2022.12.005
title: 'Investigation of serum calcium and vitamin D levels in superior semicircular
canal dehiscence syndrome: A case control study'
findings: []
- reference: DOI:10.1097/01.mao.0000244370.47320.9a
title: Measurements of Human Middle- and Inner-Ear Mechanics With Dehiscence
of the Superior Semicircular Canal
findings: []
- reference: DOI:10.1097/01.mlg.0000150702.28451.35
title: Osteoprotegerin in the Inner Ear May Inhibit Bone Remodeling in the
Otic Capsule
findings: []
- reference: DOI:10.1097/mao.0b013e318161ab24
title: Conductive Hearing Loss Caused by Third-Window Lesions of the Inner Ear
findings: []
- reference: DOI:10.1177/000348941212100102
title: Histopathology of the Temporal Bone in a Case of Superior Canal
Dehiscence Syndrome
findings: []
- reference: DOI:10.3389/fneur.2020.00891
title: Biomechanics of Third Window Syndrome
findings: []
- reference: DOI:10.3389/fneur.2021.704095
title: 'Editorial: Third Window Syndrome'
findings: []
- reference: DOI:10.3389/fneur.2022.1035478
title: New model of superior semicircular canal dehiscence with reversible
diagnostic findings characteristic of patients with the disorder
findings: []
Disease Pathophysiology Research Report Target Disease - Disease Name: Semicircular Canal Dehiscence Syndrome (typically superior SCDS) - MONDO ID: not firmly established (entity often covered under third-window syndromes) - Category: Structural
Pathophysiology Description Core concept: A dehiscence (or extreme thinning) of otic capsule bone over a semicircular canal creates a pathological “third mobile window,” which lowers impedance on the vestibular side of the inner ear and shunts acoustic and pressure energy away from the cochlea toward the dehiscence. This redistributes fluid pressures, alters cochlear and vestibular mechanics, and produces the characteristic combination of low-frequency air–bone gaps (pseudoconductive hearing loss), supranormal bone conduction, and sound/pressure-induced vestibular symptoms (Tullio/Hennebert signs). Mechanistically, to generate conductive hearing loss the third window must be on the scala vestibuli side; patching/plugging the dehiscence can resolve the air–bone gap (mechanistic proof) (Apr 2008, Otology & Neurotology; https://doi.org/10.1097/mao.0b013e318161ab24) (merchant2008conductivehearingloss pages 4-5).
Hydromechanics and vestibular activation: The third window introduces a low-impedance pathway; “a third window will introduce a low mechanical impedance,” shunting sound/pressure, generating large transmembrane pressure gradients and traveling waves in the membranous labyrinth, with outbound flow at the dehiscence balancing inflow at the oval window (Aug 2020, Frontiers in Neurology; https://doi.org/10.3389/fneur.2020.00891) (iversen2020biomechanicsofthird pages 6-7). These waves drive hair-bundle vibration at stimulus frequency (phase-locked irregular afferent firing) and, via nonlinear fluid interactions, endolymph pumping that deflects the cupula (sustained firing in regular afferents). Plugging abolishes these phase-locked responses, consistent with mechanical origin (iversen2020biomechanicsofthird pages 6-7).
Histopathology and anatomy: Temporal bone histology from a clinically diagnosed SCDS case showed a focal bony defect (1.4 × 0.6 mm) with dura directly contacting the endosteum and membranous duct at the defect; notably, “No osteoclastic process was evident within the otic capsule,” and sensory epithelia were preserved without hydrops—supporting a developmental thin-bone predisposition with trauma trigger (Jan 2012, Annals of Otology, Rhinology & Laryngology; https://doi.org/10.1177/000348941212100102) (teixido2012histopathologyofthe pages 1-2).
Bone biology/remodeling: The otic capsule exhibits unique bone physiology with greatly suppressed remodeling. Osteoprotegerin (OPG; TNFRSF11B) is expressed in the inner ear and “may inhibit bone remodeling in the otic capsule,” providing a molecular explanation for its quiescent remodeling state (Jan 2005, The Laryngoscope; https://doi.org/10.1097/01.mlg.0000150702.28451.35) (tikka2023investigationofserum pages 6-6). In a 2023 gerbil SSCD model, fenestrations of the superior canal produced reversible diagnostic features—worsened low-frequency ABR thresholds (proxy for pseudoconductive hearing loss) and increased cVEMP amplitudes with low thresholds—and healed by osteoneogenesis that “resurfac[es] the SSCD without obliteration,” returning electrophysiology toward baseline (Jan 2023, Frontiers in Neurology; https://doi.org/10.3389/fneur.2022.1035478) (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15). Clinical biochemical work has explored calcium/vitamin D and bone turnover markers in SSCD patients, aligning SSCD with otic capsule bone metabolism hypotheses (Jan 2023, Journal of Otology; https://doi.org/10.1016/j.joto.2022.12.005) (tikka2023investigationofserum pages 6-6).
Diagnostic correlations: Third-window mechanics predict low-frequency air–bone gaps with normal tympanometry, improved bone conduction thresholds, and characteristically low-threshold/high-amplitude VEMPs; surgical repair normalizes measures such as SP/AP ratios on ECoG and resolves the air–bone gap in many cases (merchant2008conductivehearingloss pages 4-5, iversen2020biomechanicsofthird pages 6-7). Contemporary clinical/biomechanical overviews and editorials emphasize that SSCD is the most common third-window disorder and summarize consistent VEMP and vestibulo-ocular reflex findings (Jun 2021, Frontiers in Neurology; https://doi.org/10.3389/fneur.2021.704095) (wackym2021editorialthirdwindow pages 3-4).
Recent developments and latest research (prioritized) - Reversible animal model (2023): Surgical SSCD in gerbils demonstrated (a) low-frequency ABR threshold worsening, (b) increased cVEMP amplitudes/low thresholds, and (c) spontaneous reversal associated with osteoneogenesis and resurfacing of the dehiscence, with many measures returning toward baseline (Jan 2023; Frontiers in Neurology) (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15). - Biochemical context (2023): Case–control work investigated serum calcium and vitamin D in SSCD, referencing bone turnover markers (alkaline phosphatase, bone alkaline phosphatase, osteocalcin) and literature on osteoclastic activity in temporal bone, suggesting systemic mineral metabolism may interact with local otic capsule biology (Jan 2023; Journal of Otology) (tikka2023investigationofserum pages 6-6). - Mechanistic synthesis: Biomechanical reviews consolidate the role of pressure-driven flows, near-incompressible lymphs, and resultant traveling waves/cupular deflection in third-window states, supporting the diagnostic signatures and explaining symptom triggers (Aug 2020; Frontiers in Neurology) (iversen2020biomechanicsofthird pages 6-7).
Current applications and real-world implementations - Clinical diagnostics: High-resolution temporal bone CT to identify dehiscence; audiometry demonstrating low-frequency air–bone gaps with normal middle-ear tests; VEMPs with reduced thresholds and increased amplitudes; ECoG SP/AP ratio elevation with normalization post-plugging (merchant2008conductivehearingloss pages 4-5, iversen2020biomechanicsofthird pages 6-7, wackym2021editorialthirdwindow pages 3-4). - Surgical repair: Middle cranial fossa or transmastoid canal plugging/resurfacing to eliminate the third window, with resolution of the air–bone gap and improvement of sound/pressure-induced vertigo in many patients, consistent with mechanical mechanism (merchant2008conductivehearingloss pages 4-5, iversen2020biomechanicsofthird pages 6-7). - Emerging models: The 2023 gerbil model offers a platform for testing molecular and biomechanical interventions, showing osteoneogenesis-mediated resurfacing without canal obliteration (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15).
Expert opinions and authoritative analyses - “A third window will introduce a low mechanical impedance,” shunting energy and generating pressure gradients/waves that activate vestibular afferents; plugging abolishes phase-locked responses—biomechanical proof linking lesion to physiology (Aug 2020; Frontiers in Neurology) (iversen2020biomechanicsofthird pages 6-7). - “To produce a conductive hearing loss the third window must be on the scala vestibuli side,” and “patching/plugging the dehiscence resolves the air–bone gap” (Apr 2008; Otology & Neurotology) (merchant2008conductivehearingloss pages 4-5). - “No osteoclastic process was evident within the otic capsule” in a histopathologically verified clinical SCDS case, consistent with a thin-bone predisposition and trauma-trigger model (Jan 2012; Ann Otol Rhinol Laryngol) (teixido2012histopathologyofthe pages 1-2). - SSCD is the most common third mobile window; editorials summarize diagnostic and QOL impacts and emphasize specific biomarkers such as cochlin-tomoprotein under evaluation (Jun 2021; Frontiers in Neurology) (wackym2021editorialthirdwindow pages 3-4).
Relevant statistics and data - Audiometry: Third-window lesions (including SSCD) typically cause low- to mid-frequency air–bone gaps up to ~2 kHz with improved bone conduction and normal middle-ear measures; correction after plugging confirms causality (Apr 2008; Otology & Neurotology) (merchant2008conductivehearingloss pages 4-5). - VEMPs: Abnormally low thresholds and high amplitudes are characteristic of SSCD and reverse after repair; animal model shows cVEMP amplitude increases with larger fenestrations and returns toward baseline with resurfacing (Jan 2023; Frontiers in Neurology) (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15, iversen2020biomechanicsofthird pages 6-7). - Histology: Clinical SCDS case with 1.4 × 0.6 mm defect; dura contacting membranous duct; no osteoclasts observed (Jan 2012; Ann Otol Rhinol Laryngol) (teixido2012histopathologyofthe pages 1-2). - Biochemistry: Case–control exploration of serum calcium and vitamin D in SSCD; references to bone turnover markers and literature on temporal bone osteoclastic activity (Jan 2023; Journal of Otology) (tikka2023investigationofserum pages 6-6).
Evidence summary table | Citation (authors, year) | Publication date | Journal | URL | Focus (mechanism / diagnostic) | Core finding (1–2 sentences) | |---|---|---|---|---|---| | Wackym PA et al., 2023 | Jan 2023 | Frontiers in Neurology | https://doi.org/10.3389/fneur.2022.1035478 | Animal model / mechanism & diagnostics | Gerbil SSCD model produced reversible pseudoconductive hearing loss (worse low-frequency ABR) and increased cVEMP amplitudes/low thresholds; micro-CT and histology show bone resurfacing (osteoneogenesis) with recovery of electrophysiologic measures (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15). | | Iversen MM & Rabbitt RD, 2020 | Aug 2020 | Frontiers in Neurology | https://doi.org/10.3389/fneur.2020.00891 | Biomechanics / mechanism | Detailed biomechanical account of third-window hydromechanics: dehiscence introduces a low-impedance pathway that shunts sound/pressure, generates transmembrane pressure gradients and traveling waves that activate canal and utricular afferents, explaining VEMP and vertigo phenomena (iversen2020biomechanicsofthird pages 6-7). | | Merchant SN & Rosowski JJ, 2008 | Apr 2008 | Otology & Neurotology | https://doi.org/10.1097/mao.0b013e318161ab24 | Mechanism / clinical audiology | Seminal description of third-window effects: vestibular-side dehiscence lowers impedance, producing low-frequency air–bone gaps and enhanced bone conduction (pseudoconductive hearing loss), with resolution after surgical patching/plugging confirming mechanism (merchant2008conductivehearingloss pages 4-5). | | Chien W et al., 2007 | Feb 2007 | Otology & Neurotology | https://doi.org/10.1097/01.mao.0000244370.47320.9a | Human ear mechanics / measurements | Experimental measurements show that superior canal dehiscence behaves as a third window altering middle/inner ear mechanics, redistributing pressure and explaining clinical audiometric patterns and vestibular responses associated with SSCD (supported by biomechanical reviews) (iversen2020biomechanicsofthird pages 6-7). | | Teixidó M et al., 2012 | Jan 2012 | Annals of Otology, Rhinology & Laryngology | https://doi.org/10.1177/000348941212100102 | Histopathology / anatomy | Temporal bone histology of a clinical SSCD case showed a focal bony dehiscence with dura contacting the membranous duct; no clear osteoclastic resorption was seen, supporting thin/developmental bone predisposition and trauma-trigger hypotheses (teixido2012histopathologyofthe pages 1-2). | | Tikka T et al., 2023 | Jan 2023 | Journal of Otology | https://doi.org/10.1016/j.joto.2022.12.005 | Bone biology / clinical biochemistry | Case–control study linking SSCD with investigations of serum calcium and vitamin D; places SSCD in context of otic capsule bone metabolism and suggests roles for calcium/Vit D pathways and osteoclastic activity hypotheses in dehiscence etiology (tikka2023investigationofserum pages 6-6). |
Table: Concise summary of foundational and recent papers on superior semicircular canal dehiscence (SCDS)/third-window pathophysiology, showing publication details, URLs, focus, and 1–2 sentence core findings with supporting context citations.
Structured Annotations Key molecular players (HGNC) and related entities - TNFRSF11B (OPG; HGNC:11909): Secreted decoy receptor inhibiting RANKL; “may inhibit bone remodeling in the otic capsule,” supporting the quiescent remodeling milieu and the biology of thin bone versus active resorption in SCDS (tikka2023investigationofserum pages 6-6). - Bone turnover markers referenced clinically: alkaline phosphatase (ALPL; HGNC:436), bone alkaline phosphatase isoform; osteocalcin (BGLAP; HGNC:1048). Discussed as markers in SSCD biochemical evaluation (tikka2023investigationofserum pages 6-6). - Cochlin-tomoprotein (COCH fragment): Investigated as a specific inner-ear biomarker in perilymphatic disorders within third-window discourse (editorial context) (wackym2021editorialthirdwindow pages 3-4).
Cell types (CL) - Osteoclast (CL:0000098): Multinucleated bone-resorbing cells; implicated by broader temporal bone literature and bone marker context, though histology in one SCDS case did not show osteoclastic activity (teixido2012histopathologyofthe pages 1-2, tikka2023investigationofserum pages 6-6). - Osteoblast (CL:0000062) and bone lining cells: The otic capsule is characterized by bone quiescence with specialized lining cells; resurfacing (osteoneogenesis) observed in animal SSCD healing (wackym2023newmodelof pages 14-15). - Vestibular hair cells (e.g., CL:0000201) and afferent neurons: Activated by third-window pressure gradients/traveling waves, producing phase-locked and sustained responses (iversen2020biomechanicsofthird pages 6-7).
Anatomical locations (UBERON) - Superior semicircular canal (UBERON:0010740); otic capsule (UBERON:0001755); oval window (UBERON:0001752); round window (UBERON:0001753); utricle (UBERON:0001756). Lesion resides on vestibular side; thin or absent bone over SSC produces third-window mechanics (merchant2008conductivehearingloss pages 4-5, teixido2012histopathologyofthe pages 1-2, iversen2020biomechanicsofthird pages 6-7).
Chemical entities (CHEBI) - Calcium ion (CHEBI:29108); vitamin D (e.g., cholecalciferol, CHEBI:28940). Explored in SSCD case–control biochemistry (tikka2023investigationofserum pages 6-6).
Gene Ontology (GO) biological processes (disrupted or engaged) - Bone remodeling (GO:0046850) and regulation of osteoclast differentiation (GO:0045670): OPG/RANKL axis in otic capsule (tikka2023investigationofserum pages 6-6). - Mechanotransduction and sensory perception of sound (GO:0050957) and vestibular receptor cell stimulus detection (GO:0050911): Altered by third-window hydromechanics that impose abnormal pressure gradients/waves on hair cells (iversen2020biomechanicsofthird pages 6-7). - Endolymph and perilymph fluid transport dynamics (related to fluid shear and cupula deflection; aligns with GO terms such as cilium movement GO:0003341 in vestibular hair cell kinocilia context) (iversen2020biomechanicsofthird pages 6-7).
Cellular components (GO CC) - Otic capsule extracellular matrix (bone matrix) and perilymph/endolymph compartments; stereocilia bundle (GO:0032420) and cupula of ampulla (anatomical structure). Third-window mechanics produce transmembrane pressure differences across these compartments (iversen2020biomechanicsofthird pages 6-7, merchant2008conductivehearingloss pages 4-5).
Disease Progression (sequence of events) 1) Predisposition: Congenitally thin otic capsule bone over SSC and/or developmental anatomy predisposes to third-window formation; systemic mineral metabolism might modulate risk (teixido2012histopathologyofthe pages 1-2, tikka2023investigationofserum pages 6-6). 2) Trigger: Minor trauma, pressure events, or chronic pulsation at the middle cranial fossa can disrupt thin bone, creating a dehiscence with dura contacting the membranous duct (teixido2012histopathologyofthe pages 1-2). 3) Third-window hydromechanics: Dehiscence lowers vestibular-side impedance, shunting sound/pressure and generating pressure gradients and traveling waves in the vestibular labyrinth (merchant2008conductivehearingloss pages 4-5, iversen2020biomechanicsofthird pages 6-7). 4) Sensory consequences: Hair-bundle vibration and cupular deflection evoke phase-locked and sustained vestibular afferent activity, respectively; cochlear energy shunting yields low-frequency air–bone gaps with supranormal bone conduction (iversen2020biomechanicsofthird pages 6-7, merchant2008conductivehearingloss pages 4-5). 5) Clinical manifestation: Autophony, aural fullness, pulsatile tinnitus, sound/pressure-induced vertigo/oscillopsia, and conductive-pattern hearing loss. Diagnostics: low-threshold/high-amplitude VEMPs, CT-visible dehiscence, ECoG SP/AP changes (teixido2012histopathologyofthe pages 1-2, merchant2008conductivehearingloss pages 4-5, iversen2020biomechanicsofthird pages 6-7, wackym2021editorialthirdwindow pages 3-4). 6) Repair/healing: Surgical plugging/resurfacing often normalizes diagnostics and symptoms; in animal models, osteoneogenesis can resurface the defect and reverse electrophysiologic changes (merchant2008conductivehearingloss pages 4-5, wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15).
Phenotypic manifestations (HP) and links to mechanism - Tullio phenomenon (HP:0011510) and Hennebert sign (HP:0033533): Sound/pressure-induced vertigo/oscillopsia due to third-window-driven vestibular activation (iversen2020biomechanicsofthird pages 6-7, merchant2008conductivehearingloss pages 4-5). - Autophony (HP:0001601) and pulsatile tinnitus (HP:0000842): Aberrant hydromechanics and direct transmission pathways in third-window states (teixido2012histopathologyofthe pages 1-2, merchant2008conductivehearingloss pages 4-5). - Conductive hearing impairment (air–bone gap) (HP:0000405; low-frequency): Shunting of acoustic energy at scala vestibuli side reduces cochlear partition drive; improves with plugging (merchant2008conductivehearingloss pages 4-5). - Abnormal VEMP (HP:0033781; low thresholds, high amplitudes): Enhanced vestibular sensitivity due to third-window impedance shunting (iversen2020biomechanicsofthird pages 6-7, wackym2023newmodelof pages 1-2).
Key mechanistic evidence (with direct supporting quotes where available) - “A third window will introduce a low mechanical impedance,” generating pressure gradients/waves that activate vestibular afferents; plugging abolishes phase-locked responses (Aug 2020; Frontiers in Neurology) (iversen2020biomechanicsofthird pages 6-7). - “To produce a conductive hearing loss the third window must be on the scala vestibuli side” and plugging “resolves the air–bone gap” (Apr 2008; Otology & Neurotology) (merchant2008conductivehearingloss pages 4-5). - “No osteoclastic process was evident within the otic capsule” in histology of a clinical SCDS case (Jan 2012; Ann Otol Rhinol Laryngol) (teixido2012histopathologyofthe pages 1-2). - SSCD model “heals in situ by bony resurfacing of the SSCD without obliteration,” with ABR and cVEMP changes reversing toward baseline (Jan 2023; Frontiers in Neurology) (wackym2023newmodelof pages 14-15, wackym2023newmodelof pages 1-2).
Evidence items (primary literature; URLs and dates) - Wackym PA et al. New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder. Frontiers in Neurology. Jan 2023. https://doi.org/10.3389/fneur.2022.1035478 (wackym2023newmodelof pages 1-2, wackym2023newmodelof pages 14-15). - Iversen MM, Rabbitt RD. Biomechanics of Third Window Syndrome. Frontiers in Neurology. Aug 2020. https://doi.org/10.3389/fneur.2020.00891 (iversen2020biomechanicsofthird pages 6-7). - Merchant SN, Rosowski JJ. Conductive Hearing Loss Caused by Third-Window Lesions of the Inner Ear. Otology & Neurotology. Apr 2008. https://doi.org/10.1097/mao.0b013e318161ab24 (merchant2008conductivehearingloss pages 4-5). - Teixidó M et al. Histopathology of the Temporal Bone in a Case of Superior Canal Dehiscence Syndrome. Ann Otol Rhinol Laryngol. Jan 2012. https://doi.org/10.1177/000348941212100102 (teixido2012histopathologyofthe pages 1-2). - Tikka T et al. Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case-control study. Journal of Otology. Jan 2023. https://doi.org/10.1016/j.joto.2022.12.005 (tikka2023investigationofserum pages 6-6). - Wackym PA et al. Editorial: Third Window Syndrome. Frontiers in Neurology. Jun 2021. https://doi.org/10.3389/fneur.2021.704095 (wackym2021editorialthirdwindow pages 3-4).
Notes and limitations - Direct genetic causality for SCDS remains unestablished; molecular insights largely relate to bone remodeling biology (e.g., OPG/RANKL pathways) and unique quiescence of otic capsule bone. Histopathology can show thin bone and dura contact without active osteoclastic resorption, though other temporal bone studies document osteoclastic activity in general (teixido2012histopathologyofthe pages 1-2, tikka2023investigationofserum pages 6-6). - While most mechanistic claims are grounded in biomechanical and histologic evidence, targeted molecular pathways beyond OPG in the otic capsule require further study in human SCDS.
References
(merchant2008conductivehearingloss pages 4-5): Saumil N. Merchant and John J. Rosowski. Conductive hearing loss caused by third-window lesions of the inner ear. Otology & Neurotology, 29:282-289, Apr 2008. URL: https://doi.org/10.1097/mao.0b013e318161ab24, doi:10.1097/mao.0b013e318161ab24. This article has 431 citations and is from a peer-reviewed journal.
(iversen2020biomechanicsofthird pages 6-7): Marta M. Iversen and Richard D. Rabbitt. Biomechanics of third window syndrome. Frontiers in Neurology, Aug 2020. URL: https://doi.org/10.3389/fneur.2020.00891, doi:10.3389/fneur.2020.00891. This article has 58 citations and is from a peer-reviewed journal.
(teixido2012histopathologyofthe pages 1-2): Michael Teixido, Brian Kung, John J. Rosowski, and Saumil N. Merchant. Histopathology of the temporal bone in a case of superior canal dehiscence syndrome. Annals of Otology, Rhinology & Laryngology, 121:12-7, Jan 2012. URL: https://doi.org/10.1177/000348941212100102, doi:10.1177/000348941212100102. This article has 30 citations.
(tikka2023investigationofserum pages 6-6): Theofano Tikka, Mohd Afiq Mohd Slim, Trung Ton, Anna Sheldon, Louise J. Clark, and Georgios Kontorinis. Investigation of serum calcium and vitamin d levels in superior semicircular canal dehiscence syndrome: a case control study. Journal of Otology, 18:49-54, Jan 2023. URL: https://doi.org/10.1016/j.joto.2022.12.005, doi:10.1016/j.joto.2022.12.005. This article has 2 citations and is from a peer-reviewed journal.
(wackym2023newmodelof pages 1-2): P. Ashley Wackym, Carey D. Balaban, Olivia J. Van Osch, Brian T. Morris, Mark-Avery Tamakloe, Victoria L. Salvatore, Sudan Duwadi, Jennifer D. Gay, and Todd M. Mowery. New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder. Frontiers in Neurology, Jan 2023. URL: https://doi.org/10.3389/fneur.2022.1035478, doi:10.3389/fneur.2022.1035478. This article has 6 citations and is from a peer-reviewed journal.
(wackym2023newmodelof pages 14-15): P. Ashley Wackym, Carey D. Balaban, Olivia J. Van Osch, Brian T. Morris, Mark-Avery Tamakloe, Victoria L. Salvatore, Sudan Duwadi, Jennifer D. Gay, and Todd M. Mowery. New model of superior semicircular canal dehiscence with reversible diagnostic findings characteristic of patients with the disorder. Frontiers in Neurology, Jan 2023. URL: https://doi.org/10.3389/fneur.2022.1035478, doi:10.3389/fneur.2022.1035478. This article has 6 citations and is from a peer-reviewed journal.
(wackym2021editorialthirdwindow pages 3-4): P. Ashley Wackym, Yuri Agrawal, Tetsuo Ikezono, and Carey D. Balaban. Editorial: third window syndrome. Frontiers in Neurology, Jun 2021. URL: https://doi.org/10.3389/fneur.2021.704095, doi:10.3389/fneur.2021.704095. This article has 26 citations and is from a peer-reviewed journal.