Histopathology of Otosclerosis

O TOSCLEROSIS generally occurs as a localized bone disease in which the morphological changes are presumably limited to the otic capsule. In the majority of instances, the pathological process develops in front of the oval window in the immediate vicinity of the window margin. As the lesion expands, the window margin becomes progressively involved. Involvement of the frame of the vestibular fenestra may lead to distortion of the window architecture or to ankylosis of the stapes footplate or to both. Stapes fixation in turn causes interference with sound conduction to the inner ear. Since otosclerosis frequently involves the otic capsule and in a certain percentage leads to stapes fixation, it constitutes a common etiology for impairment of hearing in adults. Although available figures do not indicate the exact incidence of the disease, there is good evidence that, at the present time, otosclerosis accounts for the hearing loss in nearly one