Dual innervation of free gracilis muscle for facial reanimation: What we know so far

Abstract

Background: In the last decade, some institutions have begun combining the CFNG and masseteric nerve to provide dual innervation to the gracilis muscle for dynamic facial reanimation in facial paralysis patients. We reviewed the various ways that these two nerves have been coapted to provide dual innervation, and summarized the functional outcome for these methods.

Methods: A search of the Ovid EMBASE, MEDLINE, Cochrane, and Scopus databases was performed from 1946 to May 2019 for dual innervation of gracilis muscle using CFNG plus masseteric nerve for facial reanimation.

Results: A total of 184 articles were identified in the initial search, of which seven met our inclusion criteria. Three additional abstracts with 43 patients were identified but the level of details was not sufficient to include the results in the analysis. A total of 57 patients were reviewed (mean age of 42.1 years (6-79 years)). The majority of dual innervation procedures were performed using the ipsilateral masseteric nerve sutured end-to-end to the obturator nerve, and an additional CFNG connected end-to-side to the obturator nerve. In the 26 patients with Terzis scores available, there were no differences between masseteric nerve coapted end-to-end and CFNG as end-to-side to the obturator, or the reverse coaptation. All but two patients achieved function of the gracilis activated by the masseteric nerve within 2-5 months.

Conclusions: This review shows that dual innervation of the gracilis is safe; and in some cases, does appear to provide early onset gracilis activation as well as an eventual spontaneous smile.

Keywords: Dual innervation; Facial reanimation; Gracilis; Graft; Masseteric nerve; Paralysis; Plastic surgery.