Short-term versus long-term outcomes of microvascular decompression for hemifacial spasm

Background Microvascular decompression (MVD) is a useful treatment for hemifacial spasm (HFS), but the postoperative course is extremely diverse. The purpose of this study was to compare short- and long-term outcomes, find the earliest optimal time for determining the long-term outcomes, and investigate the prognostic factors involved in the outcomes over time. Methods From July 2004 to January 2015, 1341 patients who underwent MVD for HFS were enrolled. Information on clinical features, operative findings, and surgical outcomes over time were collected by performing a review of electronic medical records, and their relationships were analyzed. The outcomes of MVD at 1, 3, 6, and 9 months were individually compared against those at > 12 months after surgery. Results The mean follow-up period after surgery was 44.9 months (median, 36.8 months; range, 12.0-156.6 months). The overall improvement rate for the 1341 patients was 89.0%. Individual postoperative outcomes at 6 and 9 months showed no differences with those at > 12 months after surgery. Furthermore, in the uni- and multi-variable analyses, patients in whom the offending vessels were intraoperatively determined to be veins showed bad outcomes at 6, 9, and > 12 months (p = 0.048, p = 0.004, and p = 0.003, respectively). Patients with intraoperative indentation on the facial nerve showed good outcomes at 6, 9, and > 12 months (p = 0.005, p = 0.039, and p = 0.020, respectively). Patients with delayed facial palsy after surgery showed better outcomes at 6, 9, and > 12 months (p = 0.002, p = 0.003, and p = 0.028, respectively). Conclusions Short- and long-term outcomes of MVD in patients with HFS manifested differently, but the outcomes at 6 and 9 months showed similarities with those at > 12 months. In patients in whom the intraoperatively detected offending vessel was not a vein, and in patients with intraoperative indentation on the facial nerve and postoperative delayed facial palsy, good outcomes could be predicted after 6 months of surgery.