What Is Canal Dehiscence Syndrome?

This disorder, also called superior semicircular canal dehiscence syndrome (SSCD), affects your balance and hearing.

"Dehiscence" is another word for hole. If you have SSCD, you have a hole or a very thin place in the bone in your ear that helps your body balance itself. It also can cause problems with the way sound comes into your ear.

SSCD is a rare condition -- only 1% to 2% of the population has been diagnosed with it. Not everyone with the syndrome has symptoms, so the number of people who have it could be slightly higher.

It affects men and women equally. People usually discover they have it in their 40s.

Symptoms

When you have SSCD, you might have one or more of the following:

  • Echoes of sounds in your ear, like when you eat or talk (called autophony)
  • Fullness in your ears
  • Hearing loss
  • Internal noises, like your heartbeat, that are louder than normal
  • Quick side to side or up and down movements of your eyes (called nystagmus)
  • Ringing in your ears
  • Sound of your pulse in your ears
  • Unsteadiness
  • Vertigo or dizziness

These symptoms can be triggered when you:

  • Cough or sneeze
  • Feel pressure changes
  • Hear loud sounds
  • Lift heavy objects
  • Strain

SSCD also can cause a condition that makes your brain think objects are moving when they're actually sitting still. This is called oscillopsia.

Causes

Three small looped structures inside your ear called semicircular canals have fluid in them that moves when you move. When the fluid moves, tiny hairs inside the canals also move. This tells your brain how your body is positioned. Your brain takes that information and tells your muscles how to act to help you keep your balance.

The canal that sits highest in your ear, the superior semicircular canal, is covered by bone. When you have SSCD, this bone has a hole or very thin place in it. This affects how the sensors react to movement.

A few things can cause SSCD, including:

  • A gene passed down from your parents that kept the bone in that area from growing thick enough
  • An infectious disease
  • Some form of trauma that damaged the bone

You can get SSCD in either ear. Some people have it in both. When that's the case, one ear typically causes more symptoms than the other.

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Diagnosis

Your doctor will do an exam and ask questions about your symptoms and when you have them. He may want to do a test called a videonystagmography (VNG). This test measures your eye movements in order to look for signs of a problem with your sense of balance.

You will be asked to wear goggles that will record your eye movements.

You'll follow targets with your eyes, and the person doing the exam may put your head in different positions. She also might use air or water to change the temperature slightly in your ear canal. You might feel your eyes make some jerky movements for a short time.

After the VNG, your doctor also may want you to have a test called a vestibular evoked myogenic potentials (VEMP) test. It checks the reflex in a muscle in your neck that responds to sound.

An electrode is placed on the muscle. Then you'll hear low to mid-range tones in one ear while your doctor watches the results on a monitor.

If your doctor suspects you have SSCD, she may order a CT scan of your ear to look for holes in the bone above your canals. This type of scan uses X-rays taken from different angles to show a more complete picture of your ear.

Treatment

If your symptoms are minor, you may be able to simply avoid triggers, such as loud noises or altitude changes. If you have hearing loss as a result of your SSCD, your doctor may suggest hearing aids.

If some symptoms are severe - like oscillopsia, balance issues, or autophony -- your doctor may suggest surgery. The most common surgery used to treat SSCD is called middle cranial fossa approach. A doctor takes some of your tissue or a small piece of bone from your skull and plugs the hole.

WebMD Medical Reference Reviewed by Shelley A. Borgia, CCCA on August 17, 2018

Sources

SOURCES:

Adult and Pediatric Otology and Neurotology: "Superior semicircular canal dehiscence syndrome."

American Speech Language Hearing Association: "Superior Canal Dehiscence."

Genetic and Rare Diseases Information Center: "Superior semicircular canal dehiscence syndrome."

Johns Hopkins Medicine: "Otolaryngology Head and Neck Surgery: Recent Findings."

Kids Health: "Your Ears."

Medscape: "Superior Canal Dehiscence."

Vestibular Disorders Association: "How Are Vestibular Disorders Diagnosed?" "Superior Semicircular Canal Dehiscence (SSCD)."

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