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SUPERIOR SEMICIRCULAR CANAL DEHISCENCE SYNDROME

The ear has 3 inner ear chambers that deliver position sense to the brain depending on the position of the head. These chambers are referred to as semicircular canals due to their shape. The superior semicircular canal lies against the roof of the bone of hearing, which also corresponds to the floor of the middle cranial fossa. Some individuals may have an abnormal opening or dehiscence of this chamber and is referred to as superior semicircular canal dehiscence (SSCD). This may result from slow erosion of the bone over time and aggravated by the pulsations of the brain, although no clear cause has been established.

A variety of symptoms may be attributed to SSCD. Patients may notice a sense of fullness in the affected ear. Their own voice may seem unusually loud in the affected ear and is referred to as autophony. These individuals may also hear their heart beat in the affected ear and is referred to as pulsatile tinnitus. Affected individuals may have symptoms of dizziness. This may be a sense of imbalance and can be severe. Further, loud sounds may be uncomfortable and cause a sense of dizziness. Individuals with SSCD may also have an associated conductive hearing loss, which at times may be confused with otosclerosis or other middle ear hearing disorders.

The diagnosis is made with a high resolution CT scan of the temporal bone. The diagnosis is often confirmed with vestibular evoked myogenic potentials.

Treatment most often requires nothing more than avoiding loud sounds. When symptoms continue and are uncomfortable however, surgical repair may be undertaken. The surgical repair is most often a resurfacing of the dehiscent portion of the semicircular canal.