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Surgeons have reanimated the hands and arms of people who are paralysed by connecting up working nerves to the injured ones, giving people the ability to use their phones, apply make-up and feed themselves again.
The surgery is life-changing, says surgeon Natasha van Zyl at Austin Health, Australia. One of her patients is currently travelling in Europe, and another can now take his grandchild to the movies by himself – both are leading drastically more independent lives than either had before.
Her team in Melbourne and several other small groups globally have been developing this technique over the last several years and seen promising results, but so far the medical literature has only focused on individual case studies or small retrospective studies.
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So van Zyl and her colleagues recruited 16 patients with spinal injuries that led to arm and leg paralysis, otherwise known as quadriplegia or tetraplegia. Most had been injured in car accidents, playing sports or through falls.
If the injury is relatively high up on the spinal cord, it can lead to arm paralysis because many of the nerves through which we control our arms branch off below the injury site. But any arm nerves that branch away from the spinal cord above the injury site will still work, for example. van Zyl and her team spliced these working nerves to the non-functioning ones that help control vital movements in the hands and elbows.
Two years after the surgery, and after intensive physical therapy, the study participants were able to open their hands, grasp, pinch and extend their elbows again.
Jeremy Simcock at the University of Otago in Christchurch, New Zealand, says this is a “landmark paper” that establishes the safety and efficacy of this surgery for people with quadriplegia.
Tendon transfer
The nerve transfer technique is similar in some ways to a tendon transfer technique, which Simcock says surgeons have been using for about 30 years to help people with tetraplegic injury use their hands.
But unlike tendon transfers, which usually involves re-routing one tendon to provide one muscular function, multiple nerve transfers can be done at once and each one can reanimate multiple muscles.
“It’s a bit like if you can imagine going in with a toolbox – it’s just doubled. It’s got twice the number of tools that it once had and some of the tools do things that you could have never done before,” says Simcock.
Each patient in the study was given at least one nerve transfer, and many had an additional tendon transfer.
Strength and dexterity
Tendon transfer surgery typically provides individuals with more strength in their hands than nerve transfers do. The average pinch strength following a tendon transfer is around two kilograms, compared to 1.5 kilograms for those with a nerve transfer.
“It’s a stronger hand [following just tendon transfer], but it’s a bit more clawed in its position and not as natural in its feeling [as with a nerve transfer],” says van Zyl. “It doesn’t open as well.”
Patients who had both types of surgery reported liking both for different reasons, and appreciated having more strength and more dexterity.
Of the 50 nerve transfers performed in the study, four failed in three different patients. van Zyl says it’s not clear exactly why the surgery didn’t work for some, but these patients received a tendon transfer to give them back some movement regardless.
Access to surgery
Each year, as many as half a million people get a spinal cord injury, and around 50 per cent of those either partially or completely lose the use of all four limbs and torso.
van Zyl and her team have performed around 160 of these nerve transfer surgeries so far, but she says many patients around the world don’t have access to the life-changing technology. She hopes the new study will help ensure that more people who are eligible are able to receive the surgery.
The surgery was predominantly performed quite early after the injury – within six months to one year – and that means that people considering the surgery need to take action earlier rather than later to get the best outcomes.
“Because essentially what you are trying to do is get the nerve to supply electricity to muscles before they wilt away,” says Simcock. “You’ve only got about 18 months to [do that].”
Journal reference: The Lancet, DOI: 10.1016/S0140-6736(19)31143-2
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