Bilateral Dehiscence of the Bony Cochlear Basal Turn

OBJECTIVE: To identify bony labyrinth defects as causing symptoms that might otherwise be difficult to understand. DESIGN: Imaging investigation on cases of lowered vestibular evoked myogenic potentials (VEMP) threshold. SETTING: Academic tertiary case-referral medical center. PATIENTS: One patient with continuous bilateral tinnitus. INTERVENTIONS: High-resolution computed tomography of petrous bone was performed after audiometry, impedance, and VEMP recording. RESULTS: We found a previously unreported dehiscence of the bony plate between the basal turn of the cochlea and the carotid canal. CONCLUSIONS: A VEMP study could prompt diagnostic imaging tests that might otherwise be neglected. Moreover, it is important to consider the possibility of a bony dehiscence involving not just the semicircular canals.