Superior canal dehiscence (SCD) is a rare disorder of the inner ear that can dramatically affect both balance and hearing. It results from a thinning or a hole (dehiscence) in the bony covering of the superior semicircular canal, one of the three semicircular canals responsible for detecting head motion and spatial awareness.

SCD occurs when the bone overlying the superior semicircular canal is absent or abnormally thin, creating a "third window" in the inner ear that disrupts the normal flow of sound and pressure. This aberration causes the inner ear to transmit signals in ways it's not supposed to, often making everyday sounds seem amplified or distorted.

The symptoms of SCD are a unique mix of auditory and vestibular (balance) disturbances: 

• Dizziness triggered by loud noises, pressure changes, coughing, or sneezing.
  
  
• Autophony, which is an unusually loud perception of one's own voice or internal sounds like heartbeat and even eye movement.
  
  
• Hearing loss, which might be conductive in nature.
  
  
• Tinnitus, often described as ringing or pulsing in the ears.
  
  
• Sound sensitivity and a sense of disequilibrium, especially with sudden movements or exertion.
  
  

These symptoms can be intermittent or chronic and are often so unusual that patients may see multiple specialists before receiving a correct diagnosis. As far as we know, SCD develops from a congenital thinning of the bone over the canal, which may be worsened by minor trauma or increased intracranial pressure later in life. It's not generally something patients cause through lifestyle or activity; rather, it’s often a developmental anomaly.

Diagnosis is typically confirmed by a combination of clinical assessment and imaging:

• High-resolution CT scan of the temporal bone to visualize the defect.
  
  
• Special vestibular evoked myogenic potential (VEMP) tests to assess the function of the inner ear and help differentiate SCD from other ear disorders.
  
  

Treatment Options

Treatment depends on severity:

• More severe or disabling cases might require surgical intervention. The most common procedures involve resurfacing or plugging the dehiscent canal, generally performed through a middle fossa craniotomy or transmastoid approach.
• Physical therapy may help manage symptoms. There is a reflex called the vestibular ocular reflex (VOR) that can become dysfunctional in many types of vertigo. It is responsible for keeping your gaze stable as you move your head. There are corrective exercises that can be done to improve this reflex.
  
  

If you or someone you know is experiencing unexplained vertigo or unusual hearing symptoms, give us a call and we can help you get on the right path.