Imaging in otosclerosis: A pictorial review

Otosclerosis is an otodystrophy of the otic capsule and is a cause of conductive, mixed or sensorineural hearing loss in the 2nd to 4th decades of life. Otosclerosis is categorised into two types, fenestral and retrofenestral. Imaging plays an important role in the diagnosis and management of otosclerosis. High-resolution CT (HRCT) of the temporal bone using 1-mm (or less) thick sections is the modality of choice for assessment of the labyrinthine windows and cochlear capsules. MRI has limited application in the evaluation of the labyrinthine capsules but is useful for assessment of the cochlear lumen prior to cochlear implantation in patients with profound hearing loss. The treatment of fenestral otosclerosis is primarily surgical with stapedectomy and prosthesis insertion. Patients with retrofenestral otosclerosis and profound hearing loss are treated medically using fluorides, but may derive significant benefit from cochlear implantation. This pictorial review aims to acquaint the reader with the pathology and clinical features of otosclerosis, the classical imaging appearances on CT and MRI, a radiological checklist for preoperative CT evaluation of otosclerosis, imaging mimics and a few examples of post-stapedectomy imaging and complications. Teaching points • Otosclerosis causes conductive, sensorineural and mixed hearing loss in adults. • HRCT of the temporal bone is the diagnostic imaging modality of choice. • Stapedectomy is used to treat fenestral otosclerosis. • Fluorides and cochlear implantation are used to treat retrofenestral otosclerosis.