Nerve transfers restored hand function and elbow extension in 13 young adults with traumatic spinal cord injury, a prospective case series from Australia showed.
Surgery to attach functioning nerves above the injury to paralyzed nerves below it, combined with 2 years of physical therapy, helped tetraplegic patients grasp, pinch, and open and close their hands and improved their ability to propel their wheelchair and transfer into a bed or a car, reported Natasha van Zyl, MBBS, of Austin Health in Melbourne, Australia, and co-authors, in The Lancet.
“Hand function is the thing that people with tetraplegia rank most highly, over and above walking and sexual function,” van Zyl told MedPage Today. “Improving hand function greatly enhances your ability to be independent, to work, and to be involved in family life.”
“Nerve transfers are a safe and feasible surgical option for restoring upper limb function in tetraplegia and can be safely and effective[ly] combined with tendon transfers,” she continued. “They unequivocally improve function and independence in people with tetraplegia.”
Upper limb function traditionally has been reconstructed with tendon transfers, which move the tendon of a functioning muscle to a new insertion site to recreate the function of a paralyzed muscle.
Nerve transfers, in contrast, allow muscles that are anatomically and biomechanically designed to do a specific function to be reanimated directly. While nerve transfers can reanimate more than one muscle at a time and multiple nerve transfers can be completed simultaneously, tendon transfers usually require one tendon to reconstruct one function. Nerve transfers also have substantially shorter immobilization periods after surgery, pose fewer surgical challenges, and offer more options for reconstruction.
In this single-center case series, van Zyl and colleagues recruited 16 people with early (less than 18 months post-injury) cervical spinal cord injury of motor level C5 and below who had been referred for upper extremity reanimation from April 2014 to November 2018. Patients were an average age of 27 and most injuries were the result of motor vehicle accidents or sports.
Surgeons performed single or multiple nerve transfers in one or both upper limbs to restore elbow extension, grasp, pinch, and hand opening by taking working nerves of expendable muscles and attaching them to nerves of paralyzed muscles. To restore the ability to extend the elbow, for example, they selected the nerve supplying the teres minor muscle in the shoulder as a donor nerve and attached it to the nerve that activates tricep muscles. They transferred the nerve to a spare wrist extensor muscle to the anterior interosseous nerve to restore the ability to grasp and pinch.
In total, surgeons worked on 27 limbs and completed 59 nerve transfers, combining nerve transfers with tendon transfers in 10 patients (12 limbs).
The 13 participants (22 limbs) who completed follow-up showed improvements at 24 months compared with baseline in total scores for all primary outcomes: action research arm test (median score 34.0 vs 16.5; P<0.0001), grasp release test (median score 125.2 vs 35.0, P<0.0001), and spinal cord independence measure (mean score 39.3 vs 31.2, which was greater than the minimal clinically important difference).
Three patients had four failed nerve transfers. Two patients experienced a decrease in sensation and two had a temporary partial decrease in wrist strength that resolved within a year after surgery. Five serious adverse events occurred, including a fall from a wheelchair with femur fracture, but none were related to surgery.
“These findings show that tendon and nerve transfers improve upper limb movement in cervical spinal cord injury,” observed Elspeth Hill, MD, PhD, and Ida Fox, MD, both of Washington University in St. Louis, in an accompanying editorial.
Nerve transfers seem to restore more natural movement and finer motor control than tendon transfers, they noted. “Nerve transfers also harness existing anatomy and physiology, which circumvents risky spine-level surgery, foreign cells, complex special equipment, and implantation of devices,” they wrote.
But nerve transfers have disadvantages, including a long runway to see results: it can take months to see new motion and years to achieve full strength. And “nerve transfers sometimes fail, and patient satisfaction does not always correlate directly with measurable gains in strength or function,” Hill and Fox added.
This project is the biggest series of nerve transfers in spinal cord injury published to date, according to van Zyl.
“It’s extremely important that people who have cervical spinal cord injury at level C5 and below know that there is something that can be done to improve hand function,” she said. “Generally speaking, nerve transfers should be done early after spinal cord injury — within 6 to 12 months — so it’s important that patients are put in contact with surgeons who do this work as soon as possible after injury.”
Further work is needed to clarify the usefulness of nerve transfers at later dates after injury and in patients of other ages, the researchers noted. Whether function and strength in reanimated muscles continue to improve beyond 24 months after surgery remains to be seen.
This study was funded by the Institute for Safety, Compensation, and Recovery Research in Australia.
The researchers reported no competing interests. The editorialists reported relationships with the Craig H Neilsen Foundation and the U.S. Department of Defense.
Source: MedicalNewsToday.com
