Superior Semicircular Canal Dehiscence Syndrome

This disorder is a recently identified cause of vertigo, imbalance, and hearing loss. Most patients will present with rather untypical balance symptoms ranging from a vague imbalance to more pronounced true vertigo. Also, many patients will have hearing loss and/or tinnitus and some patients will describe balance issues triggered by loud sounds.

As a cause for this disorder, incomplete bony coverage of the superior balance canal (superior semicircular canal) has been identified. This bony dehiscence results in what is termed a third window effect. This has been termed as such since the normal inner ear already features two windows, the oval and the round windows. With the presence of a third opening, an abnormal amount of acoustic energy is shunted through the affected balance canal resulting in the symptoms listed above.

In many cases, the symptoms are quite subtle and management includes patient education and reassurance. With more pronounces symptoms, however, surgery may become necessary. Goal of surgery is to plug the superior balance canal and thus to eliminate the third membranous opening (window) of the inner ear.