Predictors of Multi‐Vessel Identification, Outcome, and Optimal Surgical Timing for Microvascular Decompression in Hemifacial Spasm

Abstract

Objectives and BackgroundHemifacial spasm (HFS) is a disabling condition that imposes significant burden upon patients. Microvascular decompression (MVD) surgery is the most effective and long-lasting treatment for HFS, but outcomes following this surgery may vary based on a variety of clinical and operative factors. A more thorough understanding of the variables that impact patient outcome after MVD surgery is needed. MethodsA systematic review and meta-analysis of Medline, Embase, and Central was conducted (n = 2108 screened; n = 86 included) with the goal of determining the impact of the following variables on outcome: duration of disease, geographic location, intraoperative use of an endoscope, and intraoperative finding of single versus multi-vessel neurovascular compression. ResultsMost cases of hemifacial spasm occur on the left side (53.9%, p < 0.001) and are more common in women than men (66.5% versus 33.5%, p < 0.0001). The offending vessel frequencies were: 40.8% anterior inferior cerebellar artery [AICA], 24.9% posterior inferior cerebellar artery [PICA], 17.2% multiple vessels, and 4.7% vertebral artery [VA]. Multiple vessel combinations involved: 26.5% PICA + AICA, 24.6% PICA + VA, 23.1% AICA + VA, and 4.7% AICA + PICA + VA. Relative to the Americas, AICA was less frequent in Europe (p = 0.005), while PICA more frequent in Europe (p = 0.009) and Asia (p < 0.0001). With endoscope assistance, frequency of multiple vessels identified was 31.7% (versus 14.7% with non-endoscopic, p = 0.005), and 27.4% for AICA (43.5% with non-endoscopic, p = 0.003). Spasm improvement was 94.1% near discharge and 96.0% at maximum follow-up. Complications occurred in 16.5% of cases, with spasm recurrence in 2.4%. Greatest frequency of spasm improvement (p < 0.0001) and lowest spasm recurrence rates (p = 0.0005) were reported in series from Asia. For every additional month of pre-operative spasm, the effect size of post-operative improvement decreased (p = 0.04). With every subsequent postoperative month, the effect size of spasm improvement increased (p = 0.0497). The frequency of spasm improvement was significantly higher in series published after 2005 (94.4% versus 97.4%, p = 0.005). ConclusionClinical outcomes following MVD for HFS have improved since 2005. Consideration should be given to earlier operation (shorter disease duration) and use of an endoscope may increase detection of multiple offending vessels. Further studies are needed to understand regional differences in culprit vessel incidence and surgical outcomes in the Americas, Europe, and Asia.