Computed tomography-based workup of conductive hearing loss with normal middle ear: don't forget superior...

Patients with superior semicircular canal dehiscence (SSCD) may have conductive hearing loss (CHL) with normal middle ear (ME). A patient with CHL and normal tympanic membrane at otoscopy underwent tympanotomy for presumed otosclerosis but had negative intraoperative findings. A high-resolution computed tomography (CT) scan of the temporal bone performed a few years later showed the absence of middle-ear disorder (especially the absence of imaging signs of otosclerosis) and revealed a bony dehiscence of the superior semicircular canal. High-resolution CT scan is the test of choice for diagnosing SSCD; it mimics otosclerosis by manifesting itself as CHL with a normal ME. The aim of this study is to remind radiologists and otolaryngologists that SSCD should be systematically considered among the etiologies of CHL with normal ME.