C3,4 transfer for neurotization of C5,6 nerve roots in brachial plexus injury in a rabbit model.

To evaluate the root neurotization properties of extraplexal donor nerves, an avulsion injury model of brachial plexus was created and repaired by C 3,4 nerve-root transfers in the rabbit. Eighteen rabbits were divided into three groups. In Group 1 (n = 6), the right C 5,6 nerve roots were avulsed and bridged by a nerve graft taken from the femoral nerve, with C 3,4 as C 3 to C 5 and C 4 to C 6. In Group 2 (n = 6), the right C 5,6 nerve roots were cut and directly sutured end-to-end. Group 3 (n = 6) was a negative group, in which C 5,6 nerve roots were avulsed without repair. All three groups were positively controlled by the contralateral side. Postoperative behavior observation and anatomic, electrophysiologic studies were conducted 4 months later for comparison among groups. Axon existence was observed by acetylcholinesterase staining. Results showed that active motion was not found in all three groups by the end of the study. Extraplexal nerve transfer indeed was able to re-neurotize the avulsed nerve roots down to their target organ, but C 3,4 nerve transfer was weaker than direct end-to-end suture, in terms of neurotization ability. The authors conclude that "root or trunk repair" for avulsion injury of the brachial plexus is possible, provided that the donor nerve has enough fibers and the nerve regeneration ability is increased by modern moleculobiologic techniques.