Predictors of favorable outcome following hypoglossal-to-facial nerve anastomosis for facial nerve palsy: a systematic review and patient-level analysis of a literature-based cohort

Abstract

OBJECTIVE Facial nerve palsy is a debilitating condition that can arise from iatrogenic, traumatic, or congenital causes. One treatment to improve function of the facial muscles after facial nerve injury is hypoglossal-to-facial nerve anastomosis (HFA). HFA’s efficacy and predictors of its success vary in the literature. Here, the authors present a patient-level analysis of a literature-based cohort to assess outcomes and investigate predictors of success for HFA. METHODS Seven electronic databases were queried for studies providing baseline characteristics and outcomes of patients who underwent HFA. Postoperative outcomes were measured using the House-Brackmann (HB) grading scale. A change in HB grade of 3 points or more was classified as favorable. A cutoff value for time to anastomosis associated with a favorable outcome was determined using the Youden Index. RESULTS Nineteen articles with 157 patients met the inclusion criteria. The mean follow-up length was 27.4 months, and the mean time to anastomosis after initial injury was 16 months. The end-to-side and end-to-end anastomosis techniques were performed on 84 and 48 patients, respectively. Of the 130 patients who had available preoperative and postoperative HB data, 60 (46.2%) had a favorable outcome. Time from initial injury to anastomosis was significantly different between patients with favorable and unfavorable outcomes (7.3 months vs 29.2 months, respectively; p < 0.001). The optimal cutoff for time to anastomosis to achieve a favorable outcome was 6.5 months (area under the curve 0.75). Patients who underwent anastomosis within 6.5 months of injury were more likely to achieve a favorable outcome (73% vs 31%, p < 0.001). CONCLUSIONS HFA is an effective method for restoring facial nerve function. Favorable outcomes for facial nerve palsy may be more likely to occur when time to anastomosis is within a 6.5-month window.