Abstract
IMPORTANCE: A review of the role of masseteric nerve transfer is needed to guide its use in facial reanimation. OBJECTIVE: To systematically review the available literature, and, when applicable, analyze the combined outcomes of masseteric nerve transfer to better define its role in reanimation and to guide further research. DATA SOURCES: Two independent researchers conducted the review using PubMed-NCBI and Scopus literature databases for studies on masseteric nerve transfer for facial nerve paralysis. STUDY SELECTION: Studies that examined masseter nerve transfer with additional cranial nerve transposition/coaptation or muscle flap were excluded. DATA EXTRACTION AND SYNTHESIS: Literature review and data extraction followed established PRISMA guidelines. Two researchers extracted data independently. MAIN OUTCOMES AND MEASURES: The main planned outcomes for the study were quantitative results of facial nerve movement after nerve transfer including oral commissure movement and time to nerve recovery. RESULTS: A total of 13 articles met inclusion criteria with a total of 183 patients undergoing masseteric nerve transfer. From those studies, there were a total of 183 patients who underwent masseteric nerve transfer. There were 85 men and 98 women with a mean (SD) age of 43 (12.2) years and mean (SD) follow up examination after surgery of 22 (7.6) months. Mean (SD) duration of nerve paralysis was 14 (6) months. Most common cause of paralysis was cerebellopontine angle tumors (81%). Six studies coapted the masseteric nerve to the main facial nerve trunk, whereas 7 used distal branches (buccal or zygomatic). Four studies used interposition nerve grafts with great auricular nerve. Two measures, improvement in oral commissure excursion and length from reanimation to facial movement, were measured consistently across the studies. Pooled analysis showed time from surgery to first facial movement, described in 10 studies, to be 4.95 months (95% CI, 3.66 to 6.24). Distal branch coaptation improved time to recovery vs main branch coaptation, 3.76 vs 5.76 months (95% CI, -0.33 to 4.32), but mean difference was not significant. The use of interposition graft significantly delayed time of nerve recovery, 6.24 vs 4.06 months (95% CI, 0.20 to 4.16). When controlled for main trunk coaptation only, interposition nerve graft delayed recovery but difference was no longer statistically significant, 6.24 vs 4.75 months (95% CI, -0.94 to 3.92). Reported complications were minor and rare occurring in only 6.5% (12 of 183) of patients. CONCLUSIONS AND RELEVANCE: The masseteric nerve was found to be a good option for nerve transfer in this patient population, and showed favorable results in both time to nerve recovery and improvement in oral commissure excursion. LEVEL OF EVIDENCE: NA.