[Acoustic and vestibular effects of superior semicircular canal dehiscence]

A dehiscence of the superior semicircular canal is associated with many middle and inner ear symptoms of varying specificity. Concerning the pathophysiology, the way in which these symptoms are connected to a postulated missing bony layer of the superior semicircular canal remains to be completely clarified. In particular, it is unclear why a bony dehiscence might induce symptoms at all; as shown by recent experimental investigations, the natural in vivo coverage of the superior semicircular canal by dura, cerebrospinal fluid and brain prevents changes in inner ear impedance. Diagnosis of superior semicircular canal dehiscence is currently based on a combination of different tests. While cranial computed tomography (with its limited visual resolution) has proven to be largely unsuitable, ocular vestibular-evoked myogenic potentials (oVEMP) are considered an important component of diagnosis. In addition to symptomatic treatment, isolated cases also present the option of highly invasive surgical intervention. Although the majority of published case reports document positive clinical outcomes for operated patients, these procedures are associated with considerable perioperative risks.