In superior semicircular canal dehiscence, the temporal bone overlaying that canal is either thin or missing. With the gap acting as a kind of third window to the inner ear, the disorder leads to hearing and balance problems. Those who have it suffer from oversensitivity to sound. They also exhibit lower thresholds on the vestibular-evoked myogenic potential tests.
It seems to be an acquired disorder because no children have been found to have it. But the cause is unknown.
Dr. Arts said that a busy neurotologist will see only about two or three case of the disorder per year. We’re just starting to look for it in earnest, he said.