Otosclerosis and sensorineural hearing loss: a histopathologic study.

The precise role and mechanism whereby otosclerosis is associated with sensorineural hearing loss remains unclear. Previous histopathologic reports are inconsistent with regard to the location of the otosclerotic focus, invasion of the otic capsule, and the number of remaining peripheral sensorineural elements. From the combined temporal bone collections of the University of Chicago and the Mayo Clinic, we identified a group of 125 ears from 80 patients, all with confirmed otosclerosis. Six of these ears were associated clinically with sensorineural hearing loss without stapes fixation. The histopathology of the otosclerotic focus was reviewed in terms of its location and depth of invasion. The cochlea and spiral ganglion were reconstructed, and the state of the organ of Corti and the presence or absence of peripheral cochlear nerve fibers were noted. Correlations with ganglion cell counts were made. The present study showed that the pattern of degeneration of peripheral sensory and neural elements in the cases presented is very similar to that found in cases of age-related processes such as presbycusis.