Depth of stapes prosthesis in the vestibule: Baseline values and correlation with stapedectomy outcome

Conclusion: Deeper protrusion of the prosthesis into the vestibule does not correlate with worse postoperative hearing outcome. Objectives: To establish baseline values for the depth of the stapes prosthesis in the vestibule after stapedectomy and to investigate a possible correlation between the relative prosthesis depth (actual depth expressed as a percentage of the vestibule depth) and the hearing results. Methods: This was a prospective case study. Sixteeen patients underwent stapedectomy and were examined by high-resolution CT of the temporal bone during the first week after surgery. They then underwent audiometric follow-up at specified intervals during the first postoperative year. The actual depth of the prosthesis in the vestibule, its relative depth, and correlations between the relative depth and postoperative hearing results (at 1 week, 1 month, and 1 year) or postoperative complications (prolonged vertigo and sensorineural hearing loss) were measured. Results: The actual depth of the prosthesis in the vestibule (mean ± SD) was 2.39 ± 0.42 mm (range 1.833.39 mm). The depth of the prosthesis relative to the depth of the vestibule was 52 ± 9.74% (range 41.374.2%). In general, deeper protrusion of the prosthesis into the vestibule did not correlate with a worse hearing outcome. On the contrary, the correlation between prosthesis depth and better hearing results was positive at several frequencies.