Delayed relief of hemifacial spasm after microvascular decompression: can it be avoided?

Background: Although microvascular decompression (MVD) surgery has been widely accepted as an effective treatment for hemifacial spasm (HFS), delayed relief cases have been frequently reported. Therefore, the value of an immediate redo MVD should be discussed.
Methods: This study included 1,435 HFS patients who underwent MVD with intraoperative abnormal muscle response (AMR) monitoring from 2011 through 2013 at XinHua Hospital. These cases were analyzed retrospectively with emphasis on the postoperative outcomes and introaperative findings.
Results: After MVD, 1,384 HFS patients obtained relief immediately. The 51 unrelieved patients underwent AMR monitoring again the next day; this was positive in 48 and negative in 3 patients. These three patients with negative AMR obtained relief spontaneously within a week. Among the 48 positive patients, 31 and 11 were underwent redo MVD within a week and 5-22 months, respectively, and all achieved relief after the second operation. Of the six remainig patients, two obtained relief within 2 months and 4 remained unchanged in the up-to-3-year's follow-up period. In redo MVDs, insufficient decompression of the facial nerve accounted for the failure. Finally, in this database, the immediate postoperative cure rate was 96.4 %; with earlier redo MVD, the final cure rate could be increased to 99.9 %.
Conclusions: Despite being a reasonable remedy for HFS in the hands of an experienced neurosurgeon, sometimes small vessels can be missed while managing the main offending arteries during MVDs, which might account for the delayed relief. Therefore, reexamination of the AMR is necessary for unimproved patients; if a positive result is recorded, an immediate redo MVD is suggested.