FACIAL NERVE INJURY IN MAXILLOFACIAL SURGERY: MECHANISMS, PREVENTION, AND MICROSURGICAL REPAIR OUTCOMES — A META-ANALYSIS OF CLINICAL TRIALS

Abstract

Background: Facial nerve injury is one of the most distressing complications in oral and maxillofacial surgery, resulting in functional, aesthetic, and psychosocial consequences. Although intraoperative monitoring and microsurgical repair techniques have evolved, their comparative efficacy and long-term outcomes remain variably reported. Objective: To synthesize evidence from clinical trials evaluating the mechanisms, preventive strategies, and microsurgical repair outcomes of facial nerve injury in maxillofacial surgery. Methods: A systematic search of PubMed, Scopus, and Cochrane Central databases (January 2000 – October 2025) was performed. Eligible studies were randomized controlled trials (RCTs) or prospective clinical trials that assessed incidence, preventive measures, or outcomes of facial nerve injury during maxillofacial, parotid, or craniofacial surgery. Outcomes were pooled using a random-effects model (RevMan 5.4). Heterogeneity was quantified by I² statistics. Risk of bias was evaluated with the Cochrane RoB 2 tool. Results: Thirty-one clinical trials (n = 4,872 participants) were included. Mechanisms of injury were iatrogenic trauma (61 %), tumor excision (23 %), and post-traumatic repair (16 %). Intraoperative nerve monitoring reduced the risk of permanent paralysis by 42 % (RR 0.58, 95 % CI 0.46–0.73, p < 0.001). Early microsurgical repair (< 6 months) achieved 78 % functional recovery (House–Brackmann grade ≤ II). Direct neurorrhaphy produced better motor outcomes than interposition nerve grafting (p = 0.03). Delayed repair beyond 12 months lowered recovery to 46 %. Conclusion: Meta-analytic synthesis demonstrates that intraoperative nerve monitoring and timely microsurgical repair significantly enhance facial nerve recovery after maxillofacial surgery. Standardized outcome scoring and long-term follow-up are essential for future guideline development.