Posterior Semicircular Canal Dehiscence: Case Series and Systematic Review

Objective:To conduct a systematic review of posterior semicircular canal dehiscence (PSCD) and to present a series of patients with PSCD with and without classic third-window symptoms.Data Sources:PubMed, Scopus, and the Cochrane Library from inception until April 2019. Case series of five patients seen in a multidisciplinary, vestibular-focused, neurotology clinic.Study Selection:Inclusion criteria: PSCD studies of symptomatology, diagnostic testing, radiology, and histopathology. Exclusion criteria: non-English articles, reviews, letters, animal studies.Data Extraction:Quality evaluated according to Oxford Center for Evidence-Based Medicine criteria and funnel plot via the Stern and Egger method.Data Synthesis:Two hundred five studies were found, and 58 studies were included. In 47 total patients, sound-induced vertigo, mixed hearing loss, and tinnitus were the most common presenting symptom. A meta-analysis of proportions using eight radiological and histopathological studies revealed an incidence of 0.38% adult ears [95% CI 0.08, 0.89] and 2.16% of adult patients [0.64, 4.54]. The incidence in pediatric patients ranged from 1.3 to 43%. Jugular bulb abnormalities were common. In our case series, four of five patients presented without third-window symptoms, while one had sound- and pressure-induced vertigo. Hearing loss in these patients was not salvageable.Conclusions:PSCD is a rare phenomenon most commonly presenting with third-window type symptoms. However, PSCD might also present with dizziness and hearing loss inconsistent with third-window symptomatology. One should be conscious of potentially poorer prognosis for hearing recovery in these patients.