The first implant to restore the walking ability of partially paralysed primates is being welcomed as a major medical breakthrough, and raises the eventuality of new wireless treatments designed for individuals with severe spinal injuries. International researchers from the Federal Institute of Technology in Lausanne are aiming to correct the damage to the spinal cord, resulting in critical messages for movement being unable to run from the brain to the muscles. The results, published in the scientific journal Nature, explore the impact of an inserted implant into the brain area controlling leg movement and a wireless receiver placed below the spinal cord.
The implant reads brain activity designed to cause leg movement and this is wirelessly passed, mimicking the original brain activity on to the pacemaker. One half of the device is a small electrode, that is implanted into the monkey’s brain. The elctrode detected signals connected to leg motion and beamed the patterns to a computer close by, which interpreted what they meant.
Two rhesus macaque monkeys with varying damage to their spinal cords, resulting in paralysis, were able to walk following the implantation of this technology. One monkey with partial paralysis, the result of broken nerves during surgical procedure, could walk after six days with the implant. The second monkey, with more severe damage to its nerves, was able to walk approximately two weeks after implantation.
Gregoire Courtine a neuroscientist who led much of the research explains: “Thanks to this brain-spine interface the animal suffering from a paralysed leg thinks about the leg movement. ”Courtine’s team has spent a total of seven years experimenting and developing this treatment. He elaborates that the brain implant “stimulates the animal who is able to recover a coordinated gait. There really is a kind of intelligence inside the spinal cord. We are not just talking about reflexes that automatically activate muscles. In the spinal cord there are networks of neurones able to take their own decisions.” David Borton, a neuroengineer at Brown Univeristy stated: “We’re actually taking brain signals and putting them back into the nervous system at the spinal cord level to activate locomotion. That hasn’t been done before.”
Courtine’s team spent seven years developing this treatment mechanism. The system is built from components that are already approved for human use. As such, Courtine believes it could be prepared for human trials in as little as five years. The experimentation was overseen by neuroscientist Dr Erwan Bezard from Bordeaux University who commented that “the primates were able to walk immediately once the brain-spine interface was activated. No physiotherapy or training was necessary.”
However, Courtine believes that there are some significant challenges for this technology in the future and that it could “take several years before this intervention can become a therapy for humans.” Many scientists are interested in the prospect of using the implant as a potential tool in rehabilitation units. Patients with partially severed spinal cords with intact but damaged nerve fibres are potential recipients of this treatment. Clinical trials in Lausanne University Hospital in Switzerland are set to examine the potential of adverse effects of the spinal receiver on individuals with severe spinal cord injuries. A neurosurgeon at the University Hospital has said that: “for the first time, I can imagine a completely paralysed patient able to move their legs through this brain-spine interface.” If this technology was to be used on humans it would require ten years of tests.