[Diagnosis of superior semicircular canal dehiscence syndrome]

To better understand superior semicircular canal dehiscence (SSCD) syndrome.

A retrospective study was conducted on 6 patients who were diagnosed with SSCD syndrome in the Otology and Skull Base Surgery group of Fudan University. The clinical presentations including symptoms, signs, auditory tests and high resolution temporal bone computed tomography were reviewed.

Four patients presented with low frequency hearing loss while acoustic reflex responses were intact. Another patient was concomitance with chronic otitis media demonstrated profound sensorineural hearing loss. The sixth patient demonstrated normal hearing. Two patients also complained of autophony, but they were unable to tolerate their own voice. Five patients presented with vertigo while 2 patients were unable to tolerate the environmental noise. All patients showed slow component vertical torsional eye movement away from the effected eye which was induced by the presence of loud sound or pressure in the middle ear or valsalva maneuver. Four patients also demonstrated vertigo induced by the loud sound, 1 patient was induced head movement by 110 dB tone. All patients were revealed variable bone defect overlying on the SSC using high resolution temporal bone CT scan with SSC reformation.

The diagnosis of SSCD syndrome was established on both the presence of bone defect overlying superior semicircular canal which was demonstrated using high resolution temporal bone CT scan, and the presence of associated vestibular and auditory symptoms and signs.