Independence of Facial Movements from the Tongue Following Hypoglossal-to-Facial Nerve Transfer Using the Plasticity Grading Score.

Background: Nerve transfers can restore lost motor function in cases of facial palsy, with recovery reliant on brain plasticity enabling volitional control. Objective: To quantify clinical and treatment factors influencing independent facial motor recovery after hypoglossal-to-facial nerve transfer. Methods: Patients with complete unilateral facial palsy who underwent hypoglossal (resultsXII) to facial (CNVII) nerve transfer were analyzed. Brain plasticity was graded using a 4-point Plasticity Grading Scale (PGS). Patient variables, including age, sex, surgical timing, follow-up duration, and rehabilitation quality, were recorded and analyzed for their relationship with PGS scores. Results: Sixty-six patients were included, with a median age of 45 years, of which 62% were male. Plasticity was classified as poor in 53% and absent in 41% of patients. No patient achieved complete independence of facial muscles from tongue movements. Higher PGS scores were associated with earlier surgical intervention (≤6 months post-trauma; p = 0.008), younger age (p = 0.001), and adherence to rehabilitation at a specialized neurorehabilitation center (p = 0.002). Conclusions: Brain plasticity after hypoglossal-to-facial nerve transfer is often limited, failing to achieve independence of facial muscles from the donor nerve. Early intervention, younger age, and specialized rehabilitation enhanced functional recovery.