Monitoring of brainstem auditory evoked potentials during microvascular decompression for hemifacial spasm

Experience in the use of intraoperative monitoring of brainstem auditory evoked potentials (BAEPs) to relieve hemifacial spasm (HFS) in 42 patients is reported. No patient was deaf before surgery. Postoperatively, one patient (2.3%) was totally deaf. Mean preoperative pure tone average (PTA) was 12.5 ± 9.2 dB. Mean postoperative PTA was 20.5 ± 18 dB (p 1 ms (18 cases). In 15 cases changes were negligible. The main concern in BAEP monitoring was to identify significant changes of the response waveform, latencies and amplitudes on-line, and to give functional warnings to the surgeon so that he or she could modify his or her maneuvers and thus prevent deterioration of the auditory pathway. It is concluded, as it has been in other studies, that intraoperative BAEP monitoring during microvascular decompression to relieve HFS reduces the risk of postoperative deafness.