Superior canal dehiscence: review of a new condition.

A new cause of sound and pressure induced vertigo, superior canal dehisence, is described. Auditory manifestations include hyperacusis to bone-conducted sounds and conductive hearing loss with normal acoustic reflexes. The diagnosis is reached by a directed history, documentation of upward and torsional nystagmus evoked by sound and pressure, and radiology. Acoustic reflexes and VEMP (vestibular evoked myogenic potentials) aid in the identification of patients with an apparent conductive loss with normal acoustic reflexes or have an asymptomatic dehiscense on radiology. Treatment involves avoidance of the precipitating stimuli. Surgical treatment, by resurfacing the dehiscence, is considered in patients with more severe symptoms.