Revaluation of the tongue function of the modified hypoglossal-to-facial transfer: a comparative cohort study

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Background and objectives Traditional end-to-end hypoglossal-to-facial anastomosis (HFA) was a common surgical procedure for uncured severe facial palsy, however, was related to tongue dysfunction. We developed a modified hypoglossal-to-facial anastomosis (MHFA) procedure with the additional process of the anastomosis of the transected hypoglossal nerve and the ramus descendens hypoglossi, aiming to salvage the tongue function. Methods We retrospectively collected 45 cases of MHFA in our center from January 2020 to December 2022. A comparative analysis was conducted from MHFA and 27 cases of HFA in the early stage at our center. The tongue disability index was used to evaluate the tongue function during the follow-up. Results Baseline characteristics were comparable between HFA ( n = 27) and MHFA ( n = 45) groups (all p > 0.05). MHFA demonstrated longer operative time (198.27 vs. 157.78 min, p < 0.001). Up to the last follow-up, MHFA showed superior outcomes: smaller tongue deviation angle (13.38° ± 9.56° vs. 23.86° ± 10.52°, mean difference 10.47°[95%CI 5.65–15.29], p < 0.001), lower incidence of severe deviation (>30°: 8.9% vs. 37.0%, p = 0.003), and reduced tongue-related complications (24.4% vs. 66.7%, p < 0.001). Specifically, MHFA had significantly fewer swallowing (11.1% vs. 37.0%, p = 0.009) and articulation defects (13.3% vs. 44.4%, p = 0.003). TDI scores were markedly lower in MHFA (1.63 ± 0.53 vs. 2.23 ± 0.50, mean difference 0.60 [0.34–0.85], p < 0.001), particularly in swallowing, articulation, and psychological subdomains (all p < 0.05). Strong correlation existed between tongue deviation and TDI scores ( r = 0.890, p < 0.001). Facial nerve recovery showed no intergroup difference (HB score improvement: 2.40 ± 0.69 vs. 2.33 ± 0.73, p = 0.699). Conclusion MHFA appears promising for reducing tongue morbidity, but its clinically relevant advantage over HFA requires prospective validation using standardized outcomes.