Histopathology of the stapes in otosclerosis.

A histopathological examination was made of 60 stapes obtained during surgery for clinical otosclerosis. The findings, correlated with the clinical history and macroscopic appearances of the stapes, led to the following observations. The histological extent of the focus of otosclerosis agrees well with the macroscopic appearance of the footplate lesion seen under the operating microscope. The earlier the age of onset of hearing loss the greater the probability of active, severe and diffuse otosclerotic involvement of the footplate. Two-thirds of the cases with diffuse and severe footplate otosclerosis had signs of active disease. A late age of onset of clinical otosclerosis tends to be associated with lesions that are limited to the anterior pole of the stapes footplate. Active otosclerosis is rare in these cases. The case for macroscopic increase in extent of the lesion with time could not be established by the data. The evidence supports the view that the severity and extent of otosclerotic disease in the footplate is determined more by age at onset than by duration of symptoms. Healing of the active focus of otosclerosis may not always occur despite a long duration of symptoms. A highly active focus in the stapes footplate can remain active for many years.