Hypoglossal and Masseteric Nerve Transfer for Facial Reanimation: A Systematic Review and Meta-Analysis

Background: Hypoglossal and masseteric nerve transfer are currently the most popular cranial nerve transfer techniques for patients with facial paralysis. The authors performed a systematic review and meta-analysis to compare functional outcomes and adverse effects of these procedures. Methods: A review of online databases was performed to include studies with four or more patients undergoing hypoglossal or masseter nerve transfer without muscle transfer or other cranial nerve transposition. Facial nerve outcomes, time to reinnervation, and adverse events were pooled and studied. Results: A total of 71 studies were included: 15 studies included 220 masseteric-facial transfers, and 60 studies included 1312 hypoglossal-facial transfers. Oral commissure symmetry at rest was better for hypoglossal transfer (2.22 ± 1.6 mm vs. 3.62 ± 2.7 mm, p = 0.047). The composite Sunnybrook Facial Nerve Grading Scale was better for masseteric transfer (47.7 ± 7.4 vs. 33.0 ± 6.4, p < 0.001). Time to first movement (in months) was significantly faster in masseteric transfer (4.6 ± 2.6 vs. 6.3 ± 1.3, p < 0.001). Adverse effects were rare (<5%) for both procedures. Conclusions: Both nerve transfer techniques are effective for facial reanimation, and the surgeon should consider the nuanced differences in selecting the correct procedure for each patient.