Hearing preservation in acoustic neuroma surgery: middle fossa versus retrosigmoid approach.

Abstract

Objective: To compare the results of the middle fossa approach with those of the retrosigmoid approach in acoustic neuroma hearing preservation surgery.

Study design: Retrospective review.

Setting: Tertiary care facility.

Patients: Patients of the otology service with acoustic neuromas and useful hearing. Fifteen intracanalicular tumors were removed via a middle fossa approach and matched with 15 intracanalicular tumors removed via the retrosigmoid approach. Four additional patients with larger tumors were operated on via the middle fossa approach and matched with patients having similar tumors removed via the retrosigmoid approach.

Main outcome measures: The 1994 Committee on Hearing and Equilibrium guidelines for the evaluation of hearing preservation in acoustic neuroma were applied. Facial nerve results were graded according to the House-Brackmann grading scale 3 months postoperatively.

Results: In the group operated on by the middle fossa approach, the average preoperative pure-tone threshold average (PTA) was 23 dB with a word recognition score (WRS) of 79%, and the postoperative PTA averaged 49 dB with a mean WRS of 56%. In the group operated on by the retrosigmoid approach, the mean preoperative PTA was 16 dB with a WRS of 95% and a postoperative PTA value of 62 dB and WRS of 51% (hearing preservation rate of 47%). The middle fossa patients had an average change in PTA of 19 dB and an average change in WRS of 20% (hearing preservation rate of 57%). Overall, the retrosigmoid patients had an average change in PTA of 42 dB and an average change in WRS of 40%. The average change in PTA for larger tumors removed via the middle fossa approach was 32 dB, whereas all matched retrosigmoid patients lost all hearing. The rate of cerebrospinal fluid leak and facial nerve outcomes were similar between the two groups. The retrosigmoid group had a higher rate of postoperative headache.

Conclusions: Compared with the retrosigmoid approach, the middle fossa approach for hearing preservation surgery yields better hearing results for intracanalicular tumors and also has a lower incidence of postoperative headache.