Prognostic significance of intraoperative facial nerve stimulus thresholds.

OBJECTIVE: Intraoperative facial nerve monitoring has reduced the incidence of facial nerve paralysis associated with acoustic neuroma surgery, but poor facial nerve outcomes continue to occur. Intraoperative prediction of facial nerve outcome would be advantageous in patient management and counseling. This study seeks to evaluate intraoperative facial nerve stimulus thresholds as a tool for predicting postoperative facial nerve outcome.

STUDY DESIGN: This study is a prospective clinical study of the prognostic value of intraoperative stimulus thresholds.

SETTING: The study was performed at a tertiary referral center.

PATIENTS: There were 109 patients undergoing excision of acoustic neuromas included in this study.

INTERVENTIONS: The minimum current required to stimulate the facial nerve at the brain stem was prospectively recorded after excision of the acoustic neuroma.

MAIN OUTCOME MEASURES: Facial nerve outcome was evaluated by the House-Brackmann grade.

RESULTS: A statistically significant relationship was found between poor initial facial nerve outcome and higher stimulus thresholds. Long-term impaired facial function was also more common in the higher stimulus group compared to that of the lower stimulus groups.

CONCLUSIONS: Although these findings suggest that intraoperative stimulus thresholds have prognostic potential, other prognostic factors should also be considered and additional research is needed.