Muscle-Nerve-Muscle Grafting for Facial Reanimation in Rats

Abstract

Objective: Facial paralysis is a devastating condition leaving patients with a myriad of aesthetic and functional consequences. Muscle-nerve-muscle (MNM) neurotization is a reinnervation technique that involves implanting an autogenous nerve graft as a conduit between an innervated “donor” muscle and a denervated “recipient” muscle. We investigated the use of MNM reinnervation, alone or in combination with electrical stimulation (ES) and testosterone propionate (TP) in comparison to nerve reanastomosis (RE), on functional recovery following rat facial nerve injury. Methods: Thirty-one male, Sprague-Dawley rats were assigned to groups: no graft (control), MNM grafting alone (MNM), MNM grafting with ES and TP (MNM+ES+TP), or RE. Harvested right facial nerve branches were used as the MNM graft. Functional recovery was assessed by behavioral observations and electromyographic recordings. Results: The MNM grafting improved muscle tone and vibrissae movement. The ES+TP treatment further enhanced muscle tone as well as reduced recovery time for coordinated movement in a manner that is comparable to those of RE. Electromyographic recordings demonstrated electrical conductance across all MNM grafts. Conclusion: These data have important implications for patients with unilateral paralysis from facial or laryngeal nerve injury, particularly those who are not candidates for nerve reanastomosis.