PREDICTIVE VALUE OF FACIAL-NERVE ELECTROPHYSIOLOGIC STIMULATION THRESHOLDS IN CEREBELLOPONTINE-ANGLE SURGERY

The predictive value of intraoperative stimulation thresholds for faci al nerve function, using a constant-current system, was examined in 49 patients undergoing resection of cerebellopontine-angle tumors. Immed iately after surgery, 75% of the 0.1-mA threshold group, 42% of the 0. 2-mA group, and 18% of the 0.3-mA or greater group had good (grade I o r II) facial nerve function. One year after surgery. 90% of the 0.1-mA group. 58% of the 9.2-mA group. and 41% of the 0.3-mA or greater grou p had grade I or II function. A statistically significant breakpoint o f 0.2 mA was found to predict good postoperative facial function. Dela yed facial paralysis occurred in 22% of patients. hut the prognosis fo r these patients was favorable. Both current stimulation threshold and duration are necessary for a meaningful comparison of data between in vestigators.