Electromyographically Guided Nerve Combing Makes Microvascular Decompression More Successful in Hemifacial Spasm with Persistent Abnormal Muscle Response

BACKGROUND: Microvascular decompression (MVD) of the facial nerve monitored intraoperatively by abnormal muscle response (AMR) activity is a common treatment for hemifacial spasm. AMR frequently persists after MVD, however, for which electromyography (EMG)-guided nerve combing sometimes is recommended. Because no research regarding the success of EMG-guided nerve combing has been published, we compared the effectiveness of nerve combing after MVD with simple MVD in cases including persistent AMR. METHODS: A retrospective study of 127 cases of hemifacial spasm treated with persistent AMR after MVD treatment occurring between January 2011 and June 2015 was conducted. Among the 127 total cases, EMG-guided nerve combing was used in 72 patients and simple MVD in 55 patients. RESULTS: For simple MVD, success rates at 1 day, 7 days, 1 month, 3 months, and 1 year after surgery were all approximately 80%; the success rates of MVD with nerve combing were significantly greater (P < 0.05) than those of simple MVD, by 15.83%, 15.4%, 17.22%, 17.65%, and 17.65%, respectively. The incidence rates of facial palsy in simple MVD were 12.73%, 14.55%, 10.91%, 3.64%, and 1.82%, respectively; those in the nerve combing group were 27.78% (P < 0.05 vs. simple MVD), 33.33% (P < 0.05), 25.00% (P = 0.05), 5.55% (P > 0.05), and 2.78% (P > 0.05), respectively. CONCLUSIONS: In cases of hemifacial spasm with persistent AMR after MVD, EMG-guided nerve combing significantly improved the success rate of the operation. Although it also significantly increased the incidence of postoperative facial palsy over the short term (up to 1 week), incidences in the long term were not significantly different.