Recovery of the brachialis muscle and brachialis branch of the musculocutaneous nerve after phrenic nerve transfer:an experimental study

Abstract

Objective To observe and compare the recovery of the brachialis muscle and brachialis branch of the musculocutaneous nerve after two phrenic nerve transfer methods.and discuss the possibility of reusing brachialis muscle and brachialis branch of the museulocutaneous nerve for functional restoration.Methods Forty-eight SD rats,weighing 150 to 200 g,were randomized into two groups(with 24 each):phrenic nerve transfer to the anterior division of the upper truck(upper trunk group)and phrenic nerve transfer to the musculocutaneous nerve(musculocutaneous group).General observation,electrophysiological and histological examination were performed 1,2 and 3 months after the surgery,respectively. Results Elbow flexion synchronized with respiration was observed 17 to 20 days postoperativdy in the upper truck group.In the musculocutaneous group this movement was observed 20 to 25 days postoperatively.Transection of the brachialis branch 3 months after phrenic nerve transfer did not affect elbow flexion in both groups.Compound muscle action potential(CMAP) amplitude recovery rate,wet weight recovery rate and muscle fiber cross-sectional area recovery rate of the brachialis muscle were not significantly different between the two groups 3 months postoperatively(P>0.05).There WaS significant difference between the two groups in the passing rate of regenerating myelinated nerve fibers 3 months postoperatively(P<0.05),the upper truck group being superior to the musculocutaneous group. Conclusion Both phrenic nerve transfer methods can lead to recovery of the brachialis muscle and brachialis branch of the musculocutaneous nerTe.Long-term recovery of the brachialis muscle is not different in two groups.However,the upper truck group has superior brachialis branch recovery. Key words: Phrenic nerve; Nerve transfer; Animals,laboratory; Brachial muscle; Brachial branch