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.
Keywords: Hemifacial spasm; Microvascular decompression; Outcome; Prognosis.