Superior Semicircular Canal Dehiscence

Superior semicircular canal dehiscence syndrome (SCDS) is a rare disorder that causes a constellation of symptoms that include hearing loss, dizziness and ringing in the ears. It typically occurs in people ages 30 to 70, and affects women more often than men.

Triggers and Symptoms of SCDS

The superior semicircular canal is one of the three balance canals in the inner ear. It helps the brain determine the vertical position of your head.

A layer of skull bone separates the top of the superior semicircular canal and the brain. But in rare cases — and for unknown reasons — this bone can become very thin or is completely absent, leading to symptoms.

Dizziness and vertigo are two common symptoms of SCDS. They are often triggered by loud, low-frequency sounds (Tulio phenomenon) or with increased pressure in the skull (Hennebert’s phenomenon) caused by heavy lifting, sexual activity, strenuous exercise, bowel movements, sneezing or childbirth.

Other common symptoms may include:

  • Autophony — an echoing sensation in the ear during speaking, walking, chewing or swallowing
  • A sense of fullness or pressure in the ear
  • Hearing one’s own heartbeats or footsteps
  • Some degree of conductive hearing loss

A missing bone over the superior semicircular canal does not always lead to symptoms. In some cases, it is discovered during an MRI or CT scan done for unrelated reasons.

Diagnosing SCDS

SCDS is diagnosed by an otologist or otolaryngologist. Diagnostic tests can include:

  • Comprehensive hearing tests
  • Videonystagmography (VNG) — a test of the function of the inner ear balance system
  • Vestibular evoked myogenic potentials (VEMP) — an electrophysiology test that evaluates responses of the inner ear using reflexes in the neck muscles in response to loud noises
  • Electrocochleography (ECochG) — a test of the electrical potential energy in the inner ear
  • CT imaging of the bone that houses the middle and inner ear

Treating SCDS

A conservative approach to managing SCDS symptoms is always tried first. People can learn to avoid the triggers that provoke symptoms. A physical therapy program focused on balance can also help control dizziness.

Surgical options to repair the bone are available if conservative therapy fails. In many cases, surgery dramatically improves or resolves the symptoms. Surgical repair of SCDS has a number of risks, including worsening of symptoms, hearing loss, persistent dizziness, stroke, bleeding and injury to the facial nerve.

Our neurotologists are experienced in treating SCDS, and will thoroughly discuss appropriate surgical options and their risks with you.