The prevalence of superior semicircular canal dehiscence in conductive and mixed hearing loss in the absence of other pathology using submillimetric temporal bone computed tomography

The objective of this study was to assess the relationship between superior semicircular canal dehiscence (SSCD) and hearing impairment. We retrospectively compared the prevalence of SSCD in the ears classified as conductive hearing loss (CHL), mixed hearing loss (MHL), and normal hearing status using submillimetric temporal bone computed tomography (TBCT) on the basis of coronal and additional reformatted planes dedicated to SSCD. From the patients with CHL (n = 127) and MHL (n = 45), the overall prevalence of SSCD in the ears classified as CHL, MHL, and normal hearing status were 6.6%, 7.2%, and 3.0%, respectively. Furthermore, the odds ratio for SSCD in the absence of any cause of hearing loss (eg, dysfunction of the tympanic membrane or middle ear, TBCT abnormalities, otosclerosis, trauma, surgery) was 5.35 in MHL (4/27; P = 0.037, 95% confidence interval, 1.1-25.81) and 3.31 in CHL (5/61; P = 0.115, 95% confidence interval, 0.75-14.63), compared with normal hearing status. Bony covering of the SSC should be specifically evaluated in patients with hearing impairment using submillimetric TBCT.