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. Sixteen 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 1.83-3.39 mm). The depth of the prosthesis relative to the depth of the vestibule was 52 +/- 9.74% (range 41.3-74.2%). 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.