In this paper, we reported our experience of intraoperative facial electromyographic recordings obtained during microvascular decompression for hemifacial spasm.
Materials and methods: Intraoperative electromyographic recordings from the mentalis muscle during stimulation of the temporal branch of the facial nerve has been attempted in 31 patients. No muscle relaxants were used except for those before intubation. Of 31 patients, 22 were female and 9 were male. The age on admission ranged from 31 to 60 years with a mean of 54 years.
Results: 1. Abnormal response appeared with a latency of about 10 msec after stimulation. This response disappeared in 30 out of 31 patients at the end of operation. In 4 patients, the abnormal response disappeared prior to decompression of the nerve. 2. 30 patients in whom the abnormal response disappeared were free of spasm immediately after surgery. Hemifacial spasm has been relieved in 28 patients with a follow up period of 6 months to 2 years and 7 months. The remaining two patients had mild spasm. The one patient in whom the abnormal response did not disappear had persistent hemifacial spasm.
Conclusion: The authors think that intraoperative facial electromyographic recording is useful to identify the blood vessel that is causing the spasm and to ensure that decompression of the nerve has been accomplished.