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/assets/MEE/images/mgb-default-thumb.png Superior Semicircular Canal Dehiscence Syndrome

Otolaryngology–Head and Neck Surgery

Canal Dehiscence Syndromes

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Canal dehiscence syndromes refer to conditions in which there is an incomplete bony covering of one or more semicircular canals (portion of the inner ear responsible for detecting motion). The incomplete bony covering can enable stimulation of the balance canal with movements that pressurize the ear or with loud sounds.

The most common type of dehiscence is superior semicircular canal dehiscence (SSCD). This condition is likely due to a congenitally thin skull base that may become thinner with age until a dehiscence develops. Posterior canal dehiscence most often occurs in the setting of a vascular structure impinging on the posterior canal.

Other causes of canal dehiscences include cholesteatoma (skin cysts), chronic otitis media, tumors or surgery.

7Common Symptoms

  • Echoes of sounds in your ear
  • Fullness in your ears
  • Internal noises (heartbeat) are louder than normal
  • Ringing in the ears (tinnitus)
  • Maneuvers such as heavy lifting, bearing down or loud sounds trigger vertigo
  • Unsteadiness
  • Quick side-to-side or up-and-down movements of your eyes

Diagnosis and Treatment

A canal dehiscence may be found when patients develop symptoms or by chance on imaging. Typically a high-resolution temporal bone CT scan is needed to diagnose. Other types of balance tests (VEMP testing) may be used to determine whether the dehiscence leads to functional changes.

Management options include observation or surgical repair. The approach and extent for surgical repair depends on the location of the dehiscence and ranges from transmastoid surgery (behind the ear) to craniotomy surgery (above the ear).

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