Microvascular decompression for hemifacial spasm after Bell's palsy: a clinical study

Abstract

Objective To study the clinical features of idiopathic hemifacial spasm (HFS) after Bell's palsy and the efficacy of microvascular decompression (MVD) of facial nerve root. Methods From April 2007 to April 2010, 550 patients with HFS were treated by a single operator of the Department of Neurosurgery, China-Japan Friendship Hospital, National Health and Family Planning Commission using MVD, 12 (2.2%) were HFS after Bell's palsy. They were all treated with facial nerve root MVD via retrosigmoid approach. The abnormal muscle response (AMR) was monitored before and during procedures. The postoperative efficacy and complications were assessed during the follow-up. Results The AMR wave forms of ipsilateral facial muscles were monitored in 12 cases before procedure. All the 12 patients had clear offending vascular compression during the procedure, 11 had obvious thickening and adhesion of local cerebral cistern. After releasing vascular decompression, the AMR waves disappeared in 11 cases. HFS disappeared immediately in 9 cases after procedure. Those of 2 cases disappeared at 2.5 and 4 months after procedure. The AMR amplitude decreased in 1 case during the operation, but did not disappeared completely. The postoperative symptom was milder than that of preoperative one, however, the symptom still attacked every day. Two patients had mild facial paralysis after procedure and they recovered in about 0.5 months. The patients were followed up for a mean of 67.5 months (range, 51-84). None of them had recrudescence. The total effective ratio was 11/12. Conclusions HFS is rare in clinical practice after Bell's palsy. Vascular compression of the facial nerve root exit zoon is the cause of HFS after Bell's palsy. MVD is an effective and safe method to cure the disease. The perioperative facial muscle AMR monitoring is helpful in differential diagnosis and efficacy evaluation. Key words: Bell palsy; Hemifacial spasm; Microvascular decompression surgery; Abnormal muscle response