Superior canal dehiscence is an inner ear condition characterized by a variety of symptoms, including:
The superior canal is the top-most canal of the inner ear. Pulsations and pressure can cause the bony portion of the canal to erode away gradually. This creates an outflow tract for the fluid compartments of the inner ear, which can cause hearing loss, dizziness, sound sensitivity, and vertigo. A cause of superior canal dehiscence is thought to be due to an increase in the intracranial pressure (fluid pressure of the brain).
The standard for diagnosing superior canal dehiscence is a CT scan followed by a vestibular evoked myogenic potential (VEMP) test. It is crucial that the CT obtain scan slices under 1 mm in thickness to ensure accurate results. Scans of 1 mm thickness or larger may show a false positive for dehiscence.
A VEMP assesses the balance organ of the ear. Sound is sent to the ear while the neck muscle is placed under tension. A VEMP result showing a decreased threshold and increased amplitude indicates superior canal dehiscence, especially when accompanied by a positive CT finding.
Some patients choose not to seek treatment for their superior canal dehiscence. This may be appropriate for individuals who are relatively sedentary, aren’t bothered by the minor symptoms, and can easily avoid activities that can trigger the dizziness and vertigo.
Several surgical options are also available to repair the superior canal and relieve the symptoms caused by the dehiscence: