Effect of stapes demineralisation on the development of cochlear otosclerosis.

Objective: The involvement of the inner ear in otosclerosis may lead to the development of cochlear otosclerosis. The aim of this study was to analyse changes in the chemical composition and microstructure of the stapes in the course of otosclerosis compared to healthy stapes.

Materials and methods: This analysis included 31 patients with otosclerosis and 9 patients without otosclerosis. Microanalytical and diffraction techniques were used to assess the elemental distribution and orientation topography of the stapes.

Results: The concentration of Ca²⁺ in the study group was significantly lower in the area of the anterior crus of the stapes than in the posterior crus. A reduction in the Ca²⁺/P³⁺ ratio in the anterior crus was associated with deteriorated bone conduction and tinnitus. Degradation of the stapes microstructure in the area of otosclerotic lesions was observed with scanning electron microscopy.

Conclusions: Bone remodelling is most significant at the closest location to typical otosclerotic lesions with hydroxyapatite porosity and scale-like bone formation according to scanning electron microscopy. There is a relationship between the disturbance of calcium metabolism and the development of clinical symptoms of cochlear otosclerosis.