Progress in hearing function after capping surgery for superior semicircular canal dehiscence syndrome

Abstract

Superior semicircular canal dehiscence syndrome (SCDS), which presents with comprehensive symptoms such as hyperacusis, autophony, and pressure-induced vertigo, has recently been recognized in Japan. Four SCDS patients with severe vestibular symptoms refractory to conservative treatments underwent capping surgery through the middle fossa approach. Preoperative air-bone gap (AB gap) on audiometry, abnormal cervical and ocular vestibular-evoked myogenic potentials (VEMP) and bone dehiscence in the superior semicircular canal on computed tomography were observed in all the patients. Cochlear and vestibular symptoms associated with SCDS were relieved after the operation, and VEMP was normalized. However, the AB gaps on audiometry did not completely disappear in 2 patients with SCDS. VEMP and AB gaps on audiometry may be useful to diagnose SCDS. However, AB gaps did not correlate with subjective cochlear symptoms. Some patients with SCDS may have symptoms that cannot be explained by the third window abnormality. These patients may have mild hearing dysfunction.