Single versus dual innervation in facial palsy reanimation with free functional muscle transfers: a systematic review and meta-analysis

Abstract

Background: Free functional muscle transfers (FFMTs) have emerged as the gold standard for reanimation of chronic facial palsy. However, the various options for neuronal input to power the transferred muscle remain an issue of debate, especially the question whether a single or two different nerves are used. The purpose of this study was to review the available clinical data on single versus dual innervation in FFMTs and compare their outcomes to better understand if dual innervation offers a significant benefit.

Methods: A systematic review and meta-analysis were performed. Cochrane, EMBASE and PubMed MEDLINE database were searched following PRISMA guidelines 2020. All publications providing original clinical outcome data on dual nerve innervation of FFMTs in human patients were included.

Results: The initial search yielded 451 studies of which 16 met the inclusion criteria for qualitative analysis and 4 for quantitative meta-analysis. A total of 98 patients were analysed, with 53 (51.94 %) women, mean age of 44.5 years in the single-innervation group and 41.2 years in the dual-innervation group, and an average follow-up period of 15 months. Both groups individually showed significant improvements (single innervation 41.1 %, p = 0.003, dual-innervation 50.7 %, p = 0.017). However, there is insufficient evidence to conclude a statistically significant difference in outcomes between the two methods.

Conclusion: Both methods show meaningful improvements post-treatment. The dual innervation patients tended to have longer palsy durations and slightly better but more varied post-treatment improvements with overall no statistically significant difference to the single innervation group.

Keywords: Bell’s palsy; Dual innervation; Facial palsy; Facial reanimation; Plastic surgery; Reconstructive surgery; Single innervation.

Figure 1

Flow diagram of eligible studies. After screening and applying exclusion criteria, 16 studies from the initial 451 items were included in this systematic review.

Figure 2

Visualisation of the reported postoperative improvement of included studies in percentage. Single innervation results are displayed in brown, dual innervation in black.