A few weeks ago, two paraplegic people managed to regain the mobility of their extremities in the USA. thanks to a novel technique of electrical stimulation. Now, a Swiss research team has used a similar technique to get three patients with a spinal cord injury to walk again. The research has been published simultaneously in two journals: Nature and Nature Neuroscience.
The team, led by researchers at the École Polytechnique Fédérale de Lausanne in Switzerland, describes how their specialized method of electrical epidural stimulation (EAS) helped paraplegics to recover voluntary movement of the leg, even in the absence of stimulation. In addition to that, this method worked years after the patients had suffered injuries.
“Our findings are based on a deep understanding of the underlying mechanisms we gained through years of research in animal models,” explains lead researcher and neuroscientist Grégoire Courtine. “So we could imitate in real time how the brain naturally activates the spinal cord.”
“When I released the parallel bars I felt almost as if I was walking normally. I want to train more to see how far we can go, ” said David Mzee, one of the patients who suffered an accident in 2010 while practicing sports.
An evolution in a known technique
The old technique (EEE), which involves implanting electrodes in the spine, has been investigated for several years, but so far it has been shown to be more successful in animals (such as an experiment with rats and monkeys in 2014) than in humans.
While the exact reasons why the EEA does not work well with humans remain unknown, the researchers suggest that the standard technique (called ‘tonic’ or ‘continuous’ stimulation) blocks a significant amount of proprioceptive information in humans, that makes it difficult for people to perceive the position of their limbs, even when the EES activates the muscles.
Instead, this new system employs a temporal sequence of spatially selective stimulation patterns, something the team calls “spatiotemporal” stimulation, which wirelessly transmits signals to incorporated implants that activate different muscle groups, not only stimulating nerve connections. , but they cause a new nervous growth.
“This method has the advantage that specific stimulation patterns are applied at the exact moment when the participant attempts to perform the associated movement,” the first author of one of the new articles, Fabien Wagner, told ScienceAlert. “This results in a natural integration between the participant’s voluntary attempts to produce a movement and the selective effects of the stimulation.”
Fast and promising results
The new approach produced almost instantaneous results, since the three patients examined in the study were able to walk (with the help of body weight support) after just one week of calibration with neurotechnology, and despite several years of chronic paralysis. Not only that, according to the researchers, after five months of intensive rehabilitation, patients could walk for an hour on a tape with spatiotemporal EES without muscular exhaustion or deterioration.
“This level of neurological recovery has never been observed in patients with chronic spinal cord injury,” says Wagner. “We assume that the coincidence between brain inputs and activation of the spinal cord induced by the stimulation led to neuronal plasticity within the residual spinal circuits, leading to the observed recovery of motor function,” he added.
This means that the system (a technological reproduction of the brain signals that normally control walking) seems to produce unprecedented levels of neurological recovery in paraplegic patients, by taking advantage of collateral nerves that have not been injured.
While there is no guarantee that all patients will see similar results, this is an incredibly positive finding that could give hope to thousands of people with paralysis of the legs and reduced mobility. Especially if one takes into account that the patients in the study had suffered the injuries more than four years before the treatment began.
Courtine, on the other hand, prefers to be more cautious. “It’s great to walk in the laboratory, but it’s not enough, there’s still a lot to do,” he tells El País. For this reason, he has founded a startup called GTX medical with which he will seek to develop a simple device that allows patients to carry out rehabilitation anywhere, far from a hospital.