SOUND-INDUCED AND OR PRESSURE-INDUCED VERTIGO DUE TO BONE DEHISCENCE OF THE SUPERIOR SEMICIRCULAR CANAL/

Objectives: To present symptoms, patterns of nystagmus, and computed t omographic scan identification of patients with sound- and/or pressure -induced vertigo due to dehiscence of bone overlying the superior semi circular canal. To describe anatomical findings and outcome in 2 patie nts undergoing plugging of the superior semicircular canal for treatme nt of these symptoms. Design and Setting: Prospective study of a case series in a tertiary care referral center. Patients and Results: Eight patients with vertigo, oscillopsia, and/or disequilibrium related to sound, changes in middle ear pressure, and/or changes in intracranial pressure were identified in a 2-year period. Seven of these patients a lso had vertical-torsional eye movements induced by these sound and/or pressure stimuli. The direction of the evoked eye movements could be explained by excitation or inhibition of the superior semicircular can al in the affected ear. Computed tomographic scans of the temporal bon es identified dehiscence of bone overlying the affected superior semic ircular canal in each case. Disabling disequilibrium in 2 patients pro mpted plugging of the dehiscent superior canal through a middle crania l fossa approach. Symptoms were improved in each case. One patient dev eloped recurrent symptoms requiring an additional plugging procedure a nd developed sensorineural hearing loss several days after this second procedure. Conclusions: We have identified patients with a syndrome o f vestibular symptoms induced by sound in an ear or by changes in midd le ear or intracranial pressure. These patients can also experience ch ronic disequilibrium. Eye movements in the plane parallel to that of t he superior semicircular canal were evoked by stimuli that have the po tential to cause ampullofugal or ampullopetal deflection of this canal 's cupula in the presence of a dehiscence of bone overlying the canal. The existence of such deshiscences was confirmed with computed tomogr aphic scans of the temporal bones. Surgical plugging of the affected c anal may be beneficial in patients with disabling symptoms.