Superior Canal Dehiscence

Dizziness, or a sense of being out of balance, can have many possible causes. When the likely source is a problem in the inner ear, a common cause is a condition called superior canal dehiscence. It occurs when inner ear membranes are uncovered by bone or when bones of the inner ear are damaged or become thinner. In addition to causing hearing issues, superior canal dehiscence also increases sensitivity to noises and pressure.

What Causes Superior Canal Dehiscence?

Superior canal dehiscence occurs in the uppermost (superior) part of the inner ear canal. The bony part of the ear canal may wear away or deteriorate from excessive pressure or rhythmical throbbing (pulsations). The thinner bones create a new pathway for fluid within the inner ear that can trigger dizziness and related symptoms. It’s believed to be linked to added fluid pressure in the skull and brain (intracranial pressure).

Symptoms of Superior Canal Dehiscence

A sense of being off balance (vertigo) and dizziness are among the common symptoms associated with superior canal dehiscence. Sneezing, coughing, and lifting something heavy sometimes triggers a temporary change in visual focus that usually lasts a few seconds. You may also experience:

  • Hearing your own voice as you speak (autophony)
  • Blocked or clogged sensations that don’t go away with ear popping
  • Internal sounds heard in your ears, such as your own heartbeat
  • Hearing loss relegated to the ear canal
Superior Canal Dehiscence UCI Head Neck 1 - Superior Canal Dehiscence
Superior Canal Dehiscence UCI Head Neck 2 - Superior Canal Dehiscence

Diagnosing Superior Canal Dehiscence

An analysis of eye movements is oftentimes part of the process of confirming superior canal dehiscence as a source of presented symptoms. Recommended tests include a CT scan combined with a test to determine the function of structures within the inner ear (vestibular evoked myogenic potential test) by transmitting sound waves as tension is placed on a neck muscle.

Superior Canal Dehiscence Treatments

Avoiding loud noises and other likely triggers is a common treatment for superior canal dehiscence. Avoidance of stimuli doesn’t work for all symptoms. For instance, it doesn’t usually help with autophony. If self-treatment isn’t effective, surgery may be performed to correct the bone defect.

Middle Fossa Approach
The middle fossa approach is the most common surgical procedure to correct superior canal dehiscence. It involves plugging the affected canal with fibrous tissue secured by bone chips. Part of the skull above the ear is opened to access the canal.

Transmastoid Approach
With the transmastoid approach, the affected canal is accessed behind the ear. The canal is blocked or plugged to prevent fluid flow.

Round Window Plugging

Part of the inner ear is plugged with this newer procedure. The affected inner ear is accessed directly through the ear canal.

How you are affected by superior canal dehiscence will be determined by how much the inner ear membrane has been exposed and the specific location of the abnormality or defect. Whether or not you choose to seek treatment will also depend on how bothered you are by the symptoms, how active you are, and your ability to avoid situations or movements likely to trigger discomfort.

Superior Canal Dehiscence UCI Head Neck 3 - Superior Canal Dehiscence