Facial nerve function after cerebellopontine angle surgery and prognostic value of intraoperative facial nerve monitoring: a critical evaluation.

PURPOSE: Facial nerve monitoring is often used to predict postoperative facial function after acoustic neuroma tumor removal. In this study, three methods of predicting facial nerve function were compared. These methods used various parameters of the evoked electromyographic monitoring.

MATERIALS AND

METHODS

Thirty-four patients who underwent surgery for acoustic neuroma were retrospectively reviewed. Amplitude of ongoing electromyographic activity, stimulation current thresholds, and the amplitude of evoked response were analyzed. The predictive value of the three methods was compared with actual postoperative facial nerve function.

RESULTS

One method predicted the final postoperative facial function in 90% of the patients, one method in 84%, and the final method failed to predict the final VIIth nerve function in patients with current stimulation thresholds greater than 0.05 mA.

CONCLUSION

Analysis of prognostic value showed that one of the three studied proved superior in predicting facial nerve function.