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 this issue, particularly because of evidence that otosclerosis may be a systemic (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 sections 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 prevalence of otosclerosis in the extratemporal skeleton of the 2 patients examined was < 3%. CONCLUSIONS: These findings suggest that otosclerosis is unlikely to occur outside the temporal bone. Factors unique to the otic capsule that may predispose it to otosclerosis are lack of bone remodeling and the presence of globuli interossei.