superior semicircular canal dehiscence (SSCD)

definition of SSCD

common symptoms of SSCD

common signs of SSCD

how can you test for SSCD?

management options in SSCD

Patients with hearing loss and fullness or autophony as their only complaints should be observed. A hearing aid can be helpful if a low to mid frequency conductive hearing loss is seen.

There is a real risk of hearing loss following SSCD repair (12% if performed for the first time, via a middle fossa approach and using a plugging technique) and surgery should only be offered to a patient with confirmed SSCD if:

1) Dizziness with symptoms referable to the ear that has the SSCD

2) compelling clinical history (ear fullness, autophony, oscillopsia and sound and pressure sensitivity)

3) signs of symptomatic SSCD are present on exam (nystagmus to pressure or sound, tuning forks lateralize to ear that has "normal" hearing, etc.)

4) VEMP testing shows low thresholds in the involved ear

5) High resolution CT scans reformatted to examine the superior canals in the Poschel and Stenver planes

Surgical approaches include either a middle fossa craniotomy approach performed by a neurotologic surgeon (and sometimes with a neurosurgeon) or a transmastoid approach.

MIDDLE FOSSA CRANIOTOMY - this is a surgical approach through the side of the skull, above the ear. A hole, about 2 inches square, is made in the skull, the dura (lining) of the brain is gently retracted off of the skull base, the SSCD is identified, and the defect is either plugged or resurfaced. Plugging is associated with a more stable repair but potentially with a higher risk of mild to moderate hearing loss. Although resurfacing has not yet been shown to be associated with hearing loss, there is a higher incidence of recurrence.

The other advantage to a middle fossa craniotomy is the exposure that is obtained during the surgery. Often, the skull base surround the SSCD is also very thin, or even dehiscent (like Swiss-cheese) - and requires a repair using a thin slab of bone harvested from the same bone flap that is raised during the initial craniotomy. This ensures that the entire skull base is repaired, not just the SSCD. Why is this important? Holes in the skull base can lead to other problems, like a small portion of the brain (with the lining called the dura) to push through and fill the middle ear or mastoid. This is called a meningoencephalocele.

TRANSMASTOID REPAIR - this is an approach behind the ear, through the mastoid to expose the superior canal and plug it. The actually SSCD defect is never visualized directly and new holes are made in the canal to plug it. There may be a greater risk of hearing loss using this surgical approach compared with SSCD plugging using a middle fossa craniotomy approach.

surgical repair of SSCD

Case 1 - 27 year old woman with left SSCD (video)

Case 2 - 39 year old woman with left SSCD (video)

Case 3 - 48 year old man with left SSCD and meningoencephalocele

Case 4 - 38 year old man with left SSCD (3D-temporal bone model)