Muscle-Nerve-Nerve Grafting Improves Facial Reanimation in Rats Following Facial Nerve Injury.

Steven J Charous,Jane K Schumacher,Eileen M Foecking,Michael J Hutz,Samantha E Bialek

doi:10.3389/fneur.2021.723024

Steven J Charous, Jane K Schumacher + Show 3 more

Open Access

https://doi.org/10.3389/fneur.2021.723024

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Abstract

Nerve injury resulting in muscle paralysis from trauma or surgery is a major medical problem. Repair of such injuries with existing nerve grafting and reconstructive techniques often results in less than optimal outcomes. After previously demonstrating significant return of function using muscle-nerve-muscle (MNM) grafting in a rat facial nerve model, this study compares a variant of the technique, muscle-nerve-nerve (MNN) neurotization to MNM and interposition (IP) nerve grafting. Thirty male rats were randomized into four groups (1) control with no intervention, (2) repair with IP grafts, (3) MNM grafts and (4) MNN grafts. All groups had the buccal and marginal mandibular branches of the right facial nerve resected. Return of vibrissae movement, orientation, and snout symmetry was measured over 16 weeks. Functional recovery and muscle atrophy were assessed and quantified. All interventions resulted in significant improvement in vibrissae movement and orientation as compared to the control group (p < 0.05). The MNM and MNN groups had significantly less time to forward vibrissae movement as compared to controls (p < 0.05), and a large number of animals in the MNN group had coordinated vibrissae movement at 16 weeks. MNN and IP grafts retained significantly more muscle mass as compared to control (p < 0.05). Thus, MNN grafting is a promising adjuvant or alternative technique for reanimation for patients with unilateral peripheral nerve injury who are not candidates for primary neurorrhaphy.

Highlights

Nerve injuries resulting in muscle paralysis are usually a result of trauma or surgery and represent a major medical problem
We describe the MNN grafting technique which is a variant to the MNM model in which one end of the nerve conduit is embedded into the normal muscle and the other end is anastomosed to the severed distal nerve that supplied the denervated muscle
All authors contributed to manuscript revision, read, and approved the submitted version. This is the first study to evaluate the efficacy of MNN neurotization for facial nerve injury

Summary

Introduction

Nerve injuries resulting in muscle paralysis are usually a result of trauma or surgery and represent a major medical problem. Immediate coaptation of the severed nerve is the optimal solution, but when this is not feasible, other strategies are necessary to induce restoration of muscle function. Such techniques include, nerve grafts, splitting nerves longitudinally to share fascicles with the denervated muscle, end-toside grafting, nerve-muscle pedicles, and direct muscular neurotization by implanting the distal end of a nerve into denervated muscle [1,2,3,4,5]. We previously demonstrated the feasibility and comparable results of this grafting technique to other nerve grafting techniques, and the potential of using multiple grafts in order to try to “amplify” the nerve signal and improve results further [5, 9]

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