CASE #2: Left-sided superior semicircular canal dehiscence (SCDS) in a 39 year old woman with chronic aural fullness, autophony, and dizziness

This is a 39 year old woman who presented with a several year history of worsening aural (ear fullness) and dizziness. Her dizziness was aggravated by heavy lifting and loud noises.

Her physical exam revealed nystagmus to pneumatic otoscopy and valsalva against pinched nostril and closed glottis when using the Frenzel goggles. Her hearing testing revealed supranormal bone conduction of the left ear. VEMP testing revealed large amplitude and low threshold responses of the left ear.

High resolution temporal bone CT scans revealed a 3mm SCD of the left ear.

 

 

 

Above: Three-dimensional CT scan reconstruction of the skull showing the relative location of a left-sided middle fossa craniotomy. This craniotomy is centered above the external auditory canal to gain sufficient exposure of the middle fossa skull base floor and the arcuate eminence of the left superior semicircular canal.

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1. Three-dimensional CT reconstruction of the left skull base showing a dehiscence of the left superior semicircular canal.

2. Poeschel and Stenver projections of the left temporal bone reveal a 3 millimeter SCD.

3. Using a left-sided middle fossa craniotomy approach and extradural dissection, the SCD is seen surrounded by a dehiscent tegmen. Copious irrigation is used around the exposed membraneous labyrinth.

4. Softened bone wax is used to gently plug the SCD and a cotton pledget is used to gently press the wax into the defect to ensure that both limbs are plugged.

5. NOT SHOWN - a split calverial bone graft, harvested from the middle fossa craniotomy bone flap, is used to resurface the tegmen. The patient had immediate improvement of aural fullness and autophony of the left ear and one month later had resolution of dizziness. Her hearing showed normal thresolds and speech understanding of the operated ear.