Promontory drilling in stapedectomy.

Objective: Evaluate in stapedectomy the clinical outcome and audiometric results (particularly bone conduction) of drilling the promontory because of a narrow oval window niche.

Study Design: Retrospective.

Setting: Tertiary referral center, private otology practice.

Patients: Twenty-five stapedectomy patients requiring promontory drilling who had surgery between 1995 and 2000.

Method: A total of 25 patients were evaluated with a minimum 6-month follow-up. Only patients who required promontory drilling and who had complete preoperative and postoperative audiometric testing including bone conduction were included. Promontory drilling was performed with a skeeter drill to thin the promontory. Twenty-five stapedectomy patients who did not undergo promontory drilling were randomly selected from this same period as a comparison group.

Results: In addition to the narrow oval window niche, associated anatomical findings were facial nerve overhang in five patients and an obliterated footplate in three patients. Ninety-six percent of cases were successful (<10 dB postoperative air-bone gap). The one unsuccessful case was a strut over the mobile footplate that was later successfully revised. No patients suffered from intraoperative or postoperative tinnitus or vertigo. The mean 4-frequency (500-4,000 Hz) pure-tone average revealed slight improvement in bone conduction postoperatively.

Conclusion: Drilling of the promontory in stapedectomy is required in only a small percentage of cases. Although audiometric results indicated the possibility of a slight amount of acoustic trauma from the drilling, the effect on hearing was minimal and not considered a contraindication to this procedure.