Microvascular Decompression for Hemifacial Spasm

Abstract

Although microvascular decompression (MVD) has been accepted as effective therapy for hemifacial spasm, failed surgery has been reported frequently. For a sophisticated neurosurgeon, an apparent offending artery is seldom missed. However, it is still an embarrassed situation when the neurovascular conflict site could not be approached. Clinical data were collected from consecutive 211 MVDs in 2010. Intraoperative abnormal muscle response was recorded. Among them, the neurovascular conflict was not finally discovered in 3 patients, whom were then focused on. All patients were followed up for 6 to 15 months. In 17 of the 211 MVDs, the cerebellum was hard to be retracted because of adhesions. After careful dissection, a working space was finally created in the cerebellopontine angle. However, there still were 3 cases, whose neurovascular conflict site was unable to be discovered at last because of a branch of an artery embedded in the petrous bone and made the cerebellum unmovable. With navigation of real-time abnormal muscle response, the offending artery was moved away eventually even without exposing the conflict site. Postoperatively, all the patients were completely spasm-free immediately. No recurrence was noticed in the last follow-up period. The most important thing for a successful MVD operation is to remove the offending artery off the nerve. However, if the conflict site failed to be approached after endeavors, a successful MVD can still be achieved by relocating the offending artery with the guidance of real-time electromyography even without visualization of the confliction.