Superior Semicircular Canal Dehiscence

Although the exact cause is not known, current medical evidence suggests that this rare defect, or susceptibility, is congenital (or inborn). An additional theory is an increase in intracranial pressure (inside your skull). There are also numerous cases of symptoms arising after physical trauma to the head. Histology of human temporal bones describes a dehiscent or thin overlying bone in 1-2% of the population.

• Oscillopsia—The apparent motion of objects that are known to be stationary
• Autophony—A person’s own speech or other self-generated noises (such as creaking joints, chewing, heartbeat) are unusually loud in the affected ear
• Dizziness or vertigo
• Tullio phenomenon—The patient may note that loud noises cause them to see things moving or experience a similar sensation when coughing, sneezing, or straining to lift something heavy
• Hyperacusis—Being overly-sensitive to sound
• Hearing loss—Typically in the low frequencies. This is not a true hearing loss, and thus is referred to as “pseudo-conductive hearing loss.” It is important to distinguish this disorder from otosclerosis which presents with near identical hearing loss. When this dilemma occurs, acoustic reflex testing is performed to rule out one disorder.
• A feeling of fullness in the affected ear (aural fullness or pressure)
• Tinnitus—A high pitched ringing in the ear
• Fatigue

Diagnostic testing should be done by an otolaryngologist and otologist who have experience with this condition. An otolaryngologist will perform a complete history and physical examination.

Several diagnostic methods are used to diagnose SSCD.

• Complete hearing test (audiogram) with acoustic reflexes to evaluate hearing loss and reflexes
• CT-scan of the temporal bones is the most reliable way to distinguish superior semicircular canal dehiscence from other conditions affecting the inner ear
• Vestibular Evoked Myogenic Potential (VEMP) test plays an important part in the evaluation of patients with suspected SSCD. The purpose of the VEMP test is to determine if the saccule, a part of an inner ear organ called the otolith, and the eighth nerve are intact and functioning normally.

Treatment for SSCD can only be determined after a comprehensive medical examination and full work up by an otolaryngologist and otologist who have experience with this condition.

• For patients with no symptoms (asymptomatic) observation is recommended. Patients with mild symptoms are often able to tolerate symptoms by avoiding the triggering stimuli.
• For patients whose symptoms are disabling, surgical repair of the dehiscence can be very beneficial once the condition has been diagnosed. Symptoms of oscillopsia, disabling disequilibrium, and autophony are unlikely to improve with observation or stimuli avoidance.
• Surgical resurfacing of the affected bone or plugging of the superior semicircular canal has been shown to be effective. Soft tissue grafts have also been used successfully.

You will receive a thorough diagnostic examination to evaluate if you have superior semicircular canal dehiscence and determine what course of treatment is needed. Careful monitoring and the involvement of an experienced otolaryngologist are important to the successful outcome for patients with ear, nose and throat disorders and conditions.

If you are having surgery or a procedure, you will likely be scheduled for a visit to the Weiner Center for Preoperative Evaluation for pre-operative information and tests.

The day of surgery, you will be taken care of in the operating room by otolaryngologist, anesthesiologists and nurses who specialize in surgery for patients with superior semicircular canal dehiscence. After surgery, you will go to the post-surgical care unit where you will receive comprehensive care by experienced surgical and nursing staff.

Brigham and Women’s Faulkner Hospital provides a multidisciplinary approach to patient care by collaborating with colleagues who have extensive experience in diagnosing and treating ear, nose and throat disorders and conditions. In addition, patients have full access to Brigham and Women's Hospital's world-renowned academic medical community, with its diverse specialists, and state-of-the-art facilities.