Long-term outcomes of neuromuscular retraining after hypoglossal to facial nerve transfer for facial palsy

Purpose: This retrospective multicenter cohort study aims to evaluate the long-term outcomes of neuromuscular retraining (NMR) following primary end-to-end hypoglossal-facial nerve coaptation (HFC) compared with alternative rehabilitation methods, conducted across two tertiary referral centers in Italy. Methods: Patients undergoing end-to-end HFC as the sole surgical procedure for facial reanimation between 2009 and 2023 at two university hospitals were included. Patients receiving NMR were compared with controls rehabilitated through other techniques. Facial function was assessed using the House-Brackmann (HB) and Sunnybrook scales at standardized intervals during the rehabilitation period up to 24 months postoperatively. Patients had a minimum clinical follow-up of 18 months. Patient-reported outcomes were evaluated via the Facial Disability Index (FDI) and MD Anderson Dysphagia Inventory (MDADI). Results: Thirty-nine patients were included (30 NMR group, 9 control group). NMR patients showed significant improvements in all Sunnybrook scale domains compared with controls (p < 0.001), particularly in symmetry at rest and synkinesis reduction. Improvement in voluntary movement continued up to 18 months. Sex-specific analysis indicated better synkinesis control in females beyond 12 months, although not statistically significant. Overall FDI and MDADI scores were very good, but not significantly different between groups. No significant influence of age, or time to surgery on outcomes was observed. Conclusion: Specifically designed long-term NMR following end-to-end HFC significantly enhances facial reanimation outcomes, promoting cortical plasticity and limiting synkinesis. Long-term structured rehabilitation should be considered essential for optimal recovery after HFC.