RESUMEN
OBJECTIVE: The aim of this study is to evaluate of the significance of intraoperative electrophysiologic monitoring and follow up electrophysiologic study at seven days after microvascular decompression(MVD) for hemifacial spasm(HFS). METHODS: Thirty nine patients with hemifacial spasm were included in this study and were treated with MVD of the facial nerve from Jun 1990 to May 2001. The patients were divided into a monitoring group and a non-monitoring group. We compared the surgical outcomes, operation related complications between two groups. The abnormal muscle response(AMR) of preoperative electromyographic recording appeared on the mentalis muscle during stimulation of the zygomatic branch of the facial nerve was compared with those of changed during operation, immediately after operation and at postoperative 7th day(POD 7). The relationship between degree of AMR disappearance and surgical outcome was analyzed. RESULTS: There was no difference in surgical outcomes but significant difference in the incidence of operation-related complications between two groups. The results of electrophysiologic study at POD 7 were significantly correlated with surgical outcome in the monitoring group. CONCLUSION: The electrophysiologic study is helpful for identifying the offenders, determining the adequacy of vascular decompression and decrease of operation-related complications. The clinical and electrophysiologic status of HFS after MVD has continuously changed, and therefore the results of eletrophysiologic study at POD 7 are useful for predicting the surgical outcome.