AUSTRALIA — Australian Paul Robinson, now 34, broke a vertebrae when he landed on his head in a dirt bike accident in 2015. It left him confined to a wheelchair and rarely able to leave his home.
“I had no motor and muscle control below my nipples. It also affected my arm function, and I had zero function in my hands,” he said.
But after undergoing nerve transfer surgery, a technique pioneered on spinal cord injuries by surgeons in Australia, he’s now able to use his hands and arms to propel his own wheelchair, pick up items from the ground, and with one hand use a television remote control and hold a glass.
“Before, I was confined to a wheelchair but I couldn’t push it unless I wore special gloves. If I dropped something on the ground, I had to ask someone to pick it up. I couldn’t drive. To pick up a drink, I’d have to use two hands and squeeze them up.”
“It’s made a massive difference to my life,” he said. “I can do my toilet routine on my own. As a grown man, it was very demoralizing having someone help you go to the toilet.”
Robinson was one of 16 young adults with tetraplegia (paralysis of both the upper and lower limbs) recruited by Australian surgeons for a study.
The patients underwent single or multiple nerve transfers in one or both upper limbs, to allow the elbow to extend and the hand to grasp, pinch and open. The surgery ultimately enabled 13 of the participants to regain movement and function in their elbows and hands, according to the results of the study published Thursday in the medical journal The Lancet.
Tendons vs. nerves
Traditionally, surgeons have been able to restore function to the upper limbs by using tendon transfer surgery, where muscles that still work — but are designed for another function — are moved to do the work of muscles that are paralyzed. In contrast, nerve transfers reactivate the muscle itself.
One benefit of nerve transfer is that a single nerve can reanimate multiple muscles — an important factor in spinal cord injuries when few nerves would be available, said Natasha van Zyl, a plastic and reconstructive surgeon at Austin Health in Melbourne, who led the research.
“We didn’t invent nerve transfer. We’re the first to apply it to spinal cord injury in an extensive way,” she said.
“Nerve transfer is more supple and natural, and hand opening is important for typing, swiping and using a trackpad. The hand is more clawed with a tendon transfer.” she said.
In 10 of the participants, including Robinson, nerve and tendon transfers were combined to allow different types of movement in each hand.
She said the two techniques had different advantages, with nerve transfers restoring more natural movement and finer motor control in one hand, and tendon transfers restoring more power and heavy lifting ability in the other hand.
“I’ve got less opening in my right hand, but a stronger grip. But the two hands do different things. I pick things up with my left hand and put [them] in the right hand to hold them,” he said.
In total, the team completed 59 nerve transfers in 16 participants. The three women and 13 men were assessed on their ability to complete tasks before and after surgery.
“When you ask tetraplegics, their number one priority is hand function — before walking, bladder and bowel control, and sex, ” van Zyl said.
“Without hand function, it’s hard to be involved in life. It makes a great difference. It’s really simple things. I can sit with my friends and hold a glass of wine. I can feed myself and put my make up on.”
Not a cure
The technique does have limitations and isn’t a cure for this type of paralysis. For best results, the study found nerve transfers should be performed within six to 12 months of a spinal injury, and it can take months after the surgery for movement to be restored.
Three participants had four failed nerve transfers. Two had a permanent decrease in sensation, and two had a temporary decrease in wrist strength that resolved itself by a year after the surgery.
“It should be noted that this intervention does not restore function to a pre-injury state,” said Dr. Mark Dallas, associate professor in cellular neuroscience at the University of Reading in the UK, who was not involved in the research.
“That aside, the current study demonstrates the benefits of the nerve rerouting surgery to improve mobility and the ability of our nervous system to adapt to injury through this intricate surgical intervention,” he told the Science Media Centre in London.
Van Zyl said more research is needed to figure out how to optimize the nerves before transferring them, and to predict more accurately who would benefit from the surgery.
Nerve transfers cannot be used to restore function in the legs of people with spinal cord injuries because the donor nerves need to be close to reactivate the muscle, van Zyl said.
While some experimental treatments such as cell transplants and implants of electrical stimulators could help paralyzed people walk again, Dr. Ida Fox, a physician and a surgery professor at the Washington University in St Louis, said that nerve transfers are safe, reliable and circumvented risky spine-level surgery.
“For now, nerve transfers are a cost-effective way to harness the body’s innate capability to restore movement in a paralyzed limb,” she wrote in a commentary that was published alongside the research.