Variety of audiologic manifestations in patients with superior semicircular canal dehiscence.

OBJECTIVE: To present diverse symptoms, signs, and findings on diagnostic tests of 11 patients with superior semicircular canal dehiscence (SSCD) syndrome and surgical treatments for dehiscence of 3 patients. STUDY
DESIGN: Retrospective case review.
SETTING: Tertiary neurotologic and audiologic center. PATIENTS: Patients with SSCD documented by history, physical examination, vestibular function testing, and high-resolution computed tomographic scans. INTERVENTION: Two patients underwent surgical procedures through middle fossa approach, and 1 patient underwent transmastoid repair. The rest underwent conservative treatments.
RESULTS: Eleven patients were identified as SSCD. The variety of clinical manifestations, including 1) hearing presentations: mix hearing loss (4 of 11), conductive hearing loss (3 of 11), profound sensorineural hearing loss (2 of 11), and normal hearing (2 of 11); 2) vestibular manifestations: chronic disequilibrium (8 of 11), Tullio phenomenon (7 of 11), Hennebert sign (8 of 11), tinnitus (3 of 11), and autophony (3 of 11); and 3) accompanying disorders: encephalomeningocele (1 of 11). Abnormal nystagmus was identified in 3 patients. Dehiscence of bone overlying superior semicircular canal was confirmed by high-resolution computed tomographic scan in all cases. Three patients underwent operative management. (2 through the middle fossa approach and 1 through a transmastoid repair).
CONCLUSION: Superior semicircular canal dehiscence demonstrates diverse and complex clinical features. Tegmental or petrosal bone rarefaction or mild dehiscences can be a harbinger or an aggressive cause of developing SSCD. No correlation was observed between the size of dehiscence and the severity of vestibular symptoms or the degree of hearing loss. Surgical repair of dehiscence can relieve symptoms with low morbidity.