A plastic surgeon and neurosurgeon at Washington University School of Medicine in St. Louis were successful in using peripheral nerve transfer to bypass a cervical spinal cord injury and restore partial function in both hands in a 71-year-old man. To the authors’ knowledge, this is the first report of reactivation of muscles in thumb and fingers after spinal cord injury. The surgical procedures are described in the article “Nerve transfers for the restoration of hand function after spinal cord injury. Case report,” by Susan Mackinnon, M.D., Andrew Yee, and Wilson Ray, M.D., which is published online today in the Journal of Neurosurgery. The text is accompanied by informative illustrations as well as by clear preoperative, intraoperative, and postoperative videos demonstrating nerve-activated muscle function in the patient.
The patient sustained multiple injuries in a motor vehicle accident nearly two years before surgery. One of the injuries was a complete spinal cord injury at the level of the C-7 vertebra. This rendered the man paralyzed from his waist down. It also made him lose function in his hands, including the ability to flex and extend his fingers, although there was movement in his forearms. Muscle atrophy was evident in the man’s fingers due to the long period of inactivation.
The patient underwent nerve transfer during two separate surgeries—one procedure on each side—one week apart. The surgeons selected the brachialis nerve in the upper arm as a donor nerve. This nerve is one branch of a series of nerves that originate in the spinal cord above the site of injury and hence was undamaged. Near the brachialis nerve is the upper portion of the anterior interosseous nerve. This nerve extends down the arm and activates some muscles in the hand that allow us to grasp items. In this patient the spinal cord injury had interrupted normal function of the anterior interosseous nerve, the recipient nerve, but had not eliminated its ability to function in response to intraoperative electrical stimulation. Anticipating that the donor nerve could reactivate the recipient nerve, the surgeons attached the brachialis nerve to the anterior interosseous nerve. Based on their experience (and that of others), the surgeons knew that using the brachialis nerve as a donor nerve would not cause any functional loss.
Eight months after surgery, the patient began to experience movement in the thumb and index and middle fingers of his left hand. Two months later, he exhibited similar movement in his right hand. At the time the paper was written, the patient could feed himself and “perform rudimentary writing activities” with his left hand; he could perform simple hand-to-mouth movements with his right hand. With physical therapy, the authors expect the patient will see continued improvement over the next three years. He has told his physicians that he could not be happier with his outcome.
Unlike peripheral nerve injuries, the authors speculate that spinal cord injuries may have a long—and perhaps indefinite—treatment window. The authors base this comment on small case reports of patients who were successfully treated more than 6 months after injury.
When asked to elaborate on how nerve transfer is better than traditional nerve graft reconstructions and tendon transfer, Dr. Ray said that nerve transfer essentially reduces the severity of the injury by placing healthy motor nerves close to motor nerves that have not received electrical impulses since the injury. This facilitates reinstatement of the passage of electrical impulses from one nerve to the next, which then leads to muscle movement. According to Dr. Ray, this healing process takes less time than traditional nerve graft repair and does not change muscle-and-tendon dynamics, which occurs when the technique of tendon transfer is used.
According to the National Spinal Cord Injury Statistical Center, there are approximately 12,000 new spinal cord injuries each year in the U.S. Spinal cord injuries are more likely to occur in young people, who face years of disability with high health care and living expenses. According to Dr. Ray. “Nerve transfers, especially in a subset of the spinal cord injury population, could provide substantial improvements in both quality of life and functional independence.”