Dehiscence of the posterior semicircular canal.

Semicircular canal dehiscence (SCD) is a condition of the inner ear wherein the temporal bone adjacent to the vestibular apparatus thins or erodes completely. It has no clear epidemiological predisposing factors that have been identified to date. Its diagnosis is made difficult by a clinical presentation that often overlaps with other pathologies of the ear. Symptoms of SCD are believed to result from a "third-window" phenomenon, which disrupts the transmission of acoustic energy in the inner ear. Symptoms, when present, may change or worsen over time, confounding the diagnosis. We present a case of SCD of the posterior canal that mimicked Meniere's disease for several decades. We also discuss the clinical findings that may steer clinical suspicion towards this diagnosis.