Facial nerve outcome with a peroperative stimulation threshold under 0.05 mA.

OBJECTIVES/HYPOTHESIS: To evaluate the facial nerve outcome postoperatively of schwannoma vestibular surgery with a stimulation threshold (ST) lower than 0.05 mA.

STUDY

DESIGN

Retrospective chart review.

METHODS

A total of 106 patients had undergone schwannoma vestibular surgery between 2002 and 2008 in a tertiary center. The ST near the brainstem was obtained after the tumor removal. Facial nerve function was evaluated according to the House-Brackmann (HB) scale immediately postoperatively and at 1 year. The results were compared among the different STs used: <0.05 mA, 0.05 mA, and >0.05 mA.

RESULTS

There were 50 patients who had an ST <0.05 mA, 45 patients who had an ST of 0.05 mA, and 11 patients who had a ST >0.05 mA. Immediately postoperatively, for all of these groups we had a preservation of facial nerve function (HB I-II) in 94%, 80%, and 36% of patients, respectively (P < .0001). At 1 year in the same groups the preservation of the facial nerve function was 100%, 93%, and 82% of patients, respectively (P < .01).

CONCLUSIONS

A proximal ST of <0.05 mA is a better predictor of facial nerve function immediately postoperatively.