A new study showcases the benefits of nerve transfer surgery — sometimes in combination with traditional tendon transfer surgery — for restoring upper limb function in people with complete paralysis.
Spinal cord injury (SCI) affects close to 290,000 people in the United States, according to recent estimates.
Of these SCI cases, about 12% result in full paralysis, which doctors refer to as complete tetraplegia.
Traditionally, surgical interventions to restore the function of the hands and arms have involved tendon transfer surgery.
To perform this procedure, surgeons take healthy, functional muscles that have a less important role and relocate them, replacing the muscles that sustained damage as a result of the injury.
Nerve transfer is an alternative to tendon transfer. Unlike the latter, nerve transfer involves reanimating, or reinnervating, the damaged muscle.
Theoretically, nerve transfer has several advantages compared with tendon transfer. Nerve transfers allow for the reanimation of several muscles at a time, and the recovery time after surgery is much shorter.
Previous studies and case reports have deemed the practice of nerve transfer to be “relatively safe and technically feasible.”
Now, a prospective study has examined the effects of nerve transfer surgery in 16 young adults, following up on their progress up to 2 years after surgery.
In this new, first-of-its-kind research, Dr. Natasha van Zyl led a team of scientists from Austin Health in Melbourne, Australia, who looked at the potential of combining “traditional tendon-based techniques with nerve transfers” for restoring “upper limb function.”
The results appear in the journal The Lancet.
Dr. Van Zyl and her colleagues recruited 16 adults with an average age of 27 years who had experienced SCI to the neck less than 18 months before the study, mostly as a result of traffic accidents or sports-related injuries.
The researchers performed one or several nerve transfers, sometimes combining nerve transfers with tendon transfers, to restore “elbow extension, grasp, pinch, and hand opening” in the participants.
Dr. Van Zyl and team used standard assessments, such as an “action research arm test […], grasp release test […], and spinal cord independence measure,” to evaluate the outcomes of their interventions.
Overall, the team performed 59 nerve transfers, and they combined nerve transfers with tendon transfers in 10 of the participants.
To evaluate the participants’ level of independence, the researchers asked them to complete tasks relating to everyday self-care activities, such as going to the toilet on their own or brushing their teeth.
The team carried out these assessments before surgery, and both 12 and 24 months after surgery.
Two years after the intervention, most participants scored high enough on the pinch and grasp strength tests to be able to perform most day-to-day activities.
Specifically, 13 of the young adults could feed themselves, brush their teeth and hair, put on makeup, write, and use electronic devices as a result of the interventions and intensive physical therapy.
The nerve transfers failed in three of the participants, but the researchers did not record any serious adverse effects in relation to the surgery.
“For people with tetraplegia, improvement in hand function is the single most important goal,” says Dr. Van Zyl.
“We believe that nerve transfer surgery offers an exciting new option, offering individuals with paralysis the possibility of regaining arm and hand functions to perform everyday tasks and giving them greater independence and the ability to participate more easily in family and work life.”
Dr. Natasha van Zyl
“What’s more, we have shown that nerve transfers can be successfully combined with traditional tendon transfer techniques to maximize benefits,” she continues.
“When grasp and pinch [were] restored using nerve transfers in one hand and tendon transfers in the other, participants consistently [reported] that they liked both hands for different reasons and would not choose to have two hands reconstructed in the same way.”
The researchers caution, however, that nerve transfer surgery has its limitations.
For instance, it may take months for movement to arise and years before the person achieves full strength in their muscles. Also, nerve transfers need to occur up to 12 months after the injury to produce the best results.
Finally, given that four nerve transfers failed in three participants, the scientists say that more research is necessary to minimize failure and evaluate which participants are best suited to nerve transfer surgery.