MRI of cochlear otosclerosis.

Cochlear otosclerosis is an uncommon cause of mixed and sensorineural hearing loss. This has a characteristic appearance on CT, producing a distinctive pericochlear hypodense double ring. However, its appearance on MRI is not as readily appreciated, producing a ring of intermediate signal in the pericochlear and perilabyrinthine regions on T(1) weighted images, demonstrating mild to moderate enhancement after gadolinium administration. Increased signal on T(2) weighted images may also be seen. Recognition of these MRI features is important as MRI may be the first modality of investigation, especially when patients present with symptoms indicative of sensorineural hearing loss. We review four patients who presented with sensoineural hearing loss, and who were imaged with MRI as the first line of investigation.