Does otosclerosis occur only in the temporal bone?

Hypothesis: Otosclerosis does not occur outside the temporal bone. Background: The widely accepted assumption that otosclerosis is confined to the temporal bone has never been tested. It is important to investigate th is issue, particularly because of evidence that otosclerosis may be a syste mic (genetic) disease that could affect other bones. Methods: Biopsies from 9 to 11 skeletal sites were obtained from 2 patients with clinical otosclerosis. Two hundred forty-one nontemporal bone section s were examined by light microscopy. Results: No nontemporal skeletal bone section showed histologic evidence of otosclerosis. The data indicate, with 95% confidence, that the true preval ence of otosclerosis in the extratemporal skeleton of the 2 patients examin ed was < 3%. Conclusions: These findings suggest that otosclerosis is unlikely to occur outside the temporal hone. Factors unique to the otic capsule that may pred ispose it to otosclerosis are lack of bone remodeling and the presence of g lobuli interossei.