Loss of elbow flexion commonly occurs following acute brachial plexus injury. The double fascicular transfer is often used in acute C5-C6 and C5-C7 root injuries, but is rarely applied in cases involving concomitant C8 or T1 root injury. The authors designed a rat model using varying severities of lower trunk injury to determine whether partial injury to the lower trunk affects nerve transfers for elbow flexion.
There were four different rat groups in which 0, 25, 75, or 100 percent of the donor lower trunk remained intact. One-fourth of the cross-sectional area of the ulnar nerve was then transferred to the musculocutaneous nerve immediately. The authors assessed outcomes using a grooming test, muscle mass, retrograde labeling of sensory/motor neurons that regenerated axons, and immunohistochemical stain of regenerated axons.
Five months after nerve transfer, rats that underwent partial injury of the lower trunk fared significantly worse than the rats in whom the donor lower trunk remained 100 percent intact, but significantly better than the rats with 0 percent intact lower trunk. Rats with 25 or 75 percent of the lower trunk intact recovered equivalent function, at both the donor and recipient sites.
Although relatively weak compared with the 100 percent intact donor lower trunk group, the partially injured donor nerve was still functional; even though the nerve sustained a partial injury, the residual axons reinnervated the target muscles. The power of the muscles following either 25 percent or 75 percent injuries was equal after the recovery. Resorting to this approach may be useful in cases in which no alternatives are available.
Toronto, Ontario, Canada; and Taoyuan and New Taipei City, Taiwan
From the Division of Plastic and Reconstructive Surgery, Hospital for Sick Children, the SickKids Program in Neurosciences & Mental Health, and Institute of Biomaterials and Biomedical Engineering, University of Toronto; the Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital; Chang Gung Medical College and Chang Gung University; and the Department of Medicine, Mackay Medical College.
Received for publication August 17, 2018; accepted March 5, 2019.
Disclosure:The authors have no financial interest in any of the products or devices mentioned in this article.
Gregory H. Borschel, M.D., Division of Plastic and Reconstructive Surgery, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada, email@example.com, Facebook: gregory.h.borschel