Prognostic Factors of Facial and Tongue Functional Outcomes Following Side-to-End Hypoglossal-Facial Nerve Transfer: A 20-Year Multidisciplinary Experience.

Introduction: Side-to-end hypoglossal-facial nerve transfer (HFT) is an established facial reanimation technique. However, evidence regarding predictors of outcomes is limited. Objective: To evaluate predictors of facial and tongue outcomes after HFT in a large series of patients with facial palsy. Methods: A retrospective review of 64 patients undergoing side-to-end HFT was conducted. Additional masseteric nerve transfer and/or cross-facial nerve grafting were performed in selected cases. Facial outcomes were evaluated with the House-Brackmann (HB) scale, the Sunnybrook Facial Grading System, and eFACE. Tongue outcomes were assessed using Martin's scale and Oral and Pharyngeal Disability Index. Multivariate regression analyses identified independent associations. Results: HB grade III or IV was achieved in 95.3% of patients. Significant improvements were observed in all facial function scales (p < 0.001). Tongue function was preserved in 98.4%. Patient-reported scores indicated good perceived oral-pharyngeal outcomes (79.3, interquartile range = 67.9-87.4). Higher age predicted poorer facial (β = -0.303, p = 0.009) and tongue (β = -0.371, p = 0.006) outcomes. Delayed recovery onset correlated with worse facial results (β = -0.389, p = 0.001). Double nerve reinnervation was associated with better facial outcomes (p = 0.007). Conclusions: This technique offers effective facial reanimation with minimal tongue morbidity. Older age and delayed recovery onset were associated with poorer outcomes, supporting tailored surgical strategies.