Impact of Otosclerosis on Auditory Ossicle Remodeling: A Scanning Electron Microscopy Analysis of Stapes Head Overloads

BACKGROUND: Otosclerosis is a pathology that interferes with the conduction of vibrations to the inner ear, triggering changes in the auditory ossicles and their associated joints due to mechanical overload. This study primarily aims to evaluate these overload-induced modifications in the stapes head resulting from the immobilization of the base of the third auditory ossicle in otosclerosis patients. MATERIAL/METHODS: We conducted a comparative analysis of patients undergoing their first surgery for otosclerosis. The test group consisted of 31 patients who underwent stapedotomy between 2020–2021. For comparison, we utilized a control group comprising stapes samples extracted during vestibular schwannoma surgeries via a transcochlear approach. A prospective analysis of bone tissue surface topography and chemical composition was executed using scanning electron microscopy (SEM). RESULTS: SEM analysis of the stapes head in otosclerosis patients relative to the control group displayed no significant differences in chemical composition or the presence of otosclerotic foci. Nonetheless, various forms of bone tissue surface damage were noted on the stapes head in all otosclerosis patients. Mild changes were evident in 90% of the samples, while small linear bone tissue fractures were observed in 58% of the samples. Furthermore, minor osteophytic changes were detected in 16% of the samples. CONCLUSIONS: The immobilization of the stapes base by otosclerotic foci instigates overloads in the incus-stapes joint, leading to the eventual remodeling of the stapes head articular surface.