End-to-side neurorrhaphy for phrenic nerve neurotization of the musculocutaneous nerve in the treatment of brachial plexus injuries:an experimental study in rats

Abstract

Objective To investigate the feasibility of end-to-side neurorrhaphy between the musculocutaneous nerve and the phrenic nerve for treatment of brachial plexus root avulsion injuries.Methods Fifty-one male Sprague-Dawley rats were randomly divided into four groups:total brachial plexus root avulsion(A),end-to-end neurorrhaphy for phrenic nerve neurotization of the musculocutaneous nerve(B),end-to-side neurorrhaphy for phrenic nerve neurotization of the musculocutaneous nerve(C),and helicoid fashion end-to-side neurorrhaphy for phrenic nerve neurotization of the musculocutaneous nerve(D).Another 9 rats expressing green fluorescent proteins(GFP+)were used for morphological observation of the regenerated nerve with fluorescence microscope.Evaluation of functional recovery including behavioral observation,histology detection and electrophysiology study were performed at intervals of 1,2 and 3 months after the surgery.Results Functional recovery of the injured forelimbs was observed in rats of all the groups except group A.Muscle force recovery rate and muscle weight recovery rate of group C and D reached 76.4% and 86.3% of those in group B and 85.6%and 87.7% of those in group B,respectively.Meanwhile function of the diaphragm was preserved.The fluorescence study revealed an abundant collateral sprouting of phrenic nerve axons originating from the site of coaptation to the distal end of the musculocutaneous nerve in all the experimental groups.Conclusion Although inferior to end-to-end neurotization,the standard end-to-side neurotization and end-to-side neurotization in helicoids fashion were effective methods,the latter resulting in better recovery. Key words: Brachial plexus; Nerve transfer; Phrenic nerve