Value of computed tomography (CT) in the diagnosis of cochlear otosclerosis.

The temporal bones of 40 patients with surgically confirmed otosclerosis were studied with high-resolution CT. The hearing of these patients was re-examined 5 years later. Foci of demineralization in the cochlear capsule were detected in 36% of operated ears and in 44% of otosclerotic ears not operated on. Mean bone conduction (BC) thresholds of ears with positive radiological findings did not differ significantly from those of otosclerotic ears with normal CT, either at the time of CT examination or 5 years later. Over 5 years, elevation of BC thresholds by 10 dB or more was observed significantly more often in operated ears with abnormal CT than in operated ears with normal CT, but in otosclerotic ears not operated on the corresponding difference was non-significant. It was concluded that CT examination is of little value in predicting sensorineural hearing loss in patients with otosclerosis.