Vestibular Aqueduct Hypoplasia Identifies Semicircular Canal Dehiscence Patients Who Progress to Meniere's Disease.

Objective: Semicircular canal dehiscence (SCD) and vestibular aqueduct (VA) hypoplasia are developmental anomalies associated with distinct inner ear syndromes-SCD syndrome and Meniere's disease (MD). Our previous work found frequent SCD in MD patients with VA hypoplasia, suggesting a shared developmental origin. To further explore this association, we adopted a reciprocal approach by assessing VA hypoplasia prevalence in patients diagnosed with SCD. Study Design: Retrospective cohort study. Setting: Tertiary referral center. Patients: A total of 219 ears from 173 patients (mean age 53.5 years, standard deviation 16.6 years; 54.3% females) were evaluated for suspected SCD, confirmed by temporal bone computed tomography (CT). Interventions: Radiological analysis of temporal bone CT scans using the angular trajectory of the vestibular aqueduct (ATVA) marker; review of clinical records for diagnosis of MD. Main Outcome Measures: Prevalence of VA hypoplasia among SCD patients; association of radiological findings with clinical diagnosis of MD. Results: VA hypoplasia was identified in 4 of 173 patients (2.3%), representing a 46-fold increase compared with the estimated 0.05% prevalence of MD patients with VA hypoplasia in the general population. These cases showed an atypical SCD localization in the posterior limb of the superior semicircular canal. All 4 patients were diagnosed with MD ipsilateral to the SCD/VA hypoplasia. Conclusions: SCD and VA hypoplasia are associated in a distinct patient group, suggesting a shared developmental etiology. These patients may be predisposed to an early overlap of SCD syndrome and MD, with their clinical course eventually dominated by the progressive nature of MD.