Eight paraplegics – some of them paralysed for more than a decade by severe spinal cord injury – have been able to move their legs and feel sensation, after help from an artificial exoskeleton, sessions using virtual reality (VR) technology and a non-invasive system that links the brain with a computer.
In effect, after just 10 months of what their Brazilian medical team call “brain training” they have been able to make a conscious decision to move and then get a response from muscles that have not been used for a decade.
Of the octet, one has been able to leave her house and drive a car. Another has conceived and delivered a child, feeling the contractions as she did so.
The extent of the improvements was unexpected. The scientists had intended to exploit advanced computing and robotic technology to help paraplegics recover a sense of control in their lives. But their patients recovered some feeling and direct command as well.
The implication is that even apparently complete spinal cord injury might leave some connected nerve tissue that could be reawakened after years of inaction.
The patients responded unevenly, but all have reported partial restoration of muscle movement or skin sensation. Some have even recovered visceral function and are now able to tell when they need the lavatory. And although none of them can walk unaided, one woman has been able to make walking movements with her legs, while suspended in a harness, and generate enough force to make a robot exoskeleton move.
“Some of our patients, for the first time, were able to get out of their houses and go back to work,” said Miguel Nicolelis, co-director of the Duke University Centre for Neuroengineering, and based at the Alberto Santos Dumont Association neurorehabilitation laboratory in São Paulo. The work is part of the Walk Again Project that unites 100 scientists from 25 countries.
The study parallels other approaches to spinal cord injury: there are hopes ofstem cell therapy that could make possible natural repairs to the nervous system, and of electronic implants that might bypass a spinal cord injury to transmit the brain’s message to the muscles.
The Brazilian trial was originally intended as a test of the third approach: robotic aids driven by brainpower. The scientists gave an example of what they thought possible in 2014 when Juan Pinto, a 25-year-old paraplegic, used a brain-controlled robotic exoskeleton to kick a football during the opening ceremony of the World Cup in Sao Paulo.
The exoskeleton technology existed. Scientists had already demonstrated in a number of ways the capacity of a computer to “read” the electrical signals from a conscious command in the brain, and perform a correct action.
But after the eight patients had performed more than 2,000 sessions of brain training, for a collective total of almost 2,000 hours, the Brazilian team began to see entirely unexpected results.
“We stumbled into this clinical recovery, which is something that is almost like a dream, because it took the approach to a whole new level,” said Dr Nicolelis.
“They have seen on their own terms a very significant improvement in their lives, in terms of mobility, of being able to feel their legs, to feel their skin; improvements in sexual performance for the men for instance. One of the ladies basically decided to deliver a baby because she now had visceral sensation.”
The scientists – 20 in all from Brazil, Switzerland, Germany and the US – describe their approach in the journal Scientific Reports. They fitted patients with electrodes that could register electroencephalogram signals from the brain. Then they asked the patients to “think” about moving their legs. None of them could do so: the motor cortex of the brain has a pronounced apparatus for representing movement, and the patients could “think” hand movements, but the leg connection had been wiped clean.
None of the patients in the experiment had benefited from any traditional rehabilitation before they joined the project. And none of the eight could control any movement below the level of the spinal cord injury.
The next stage was to introduce VR, and off-the-shelf walking devices now used in physical therapy centres for the injured, as well as overhead harnesses to get the patients accustomed to making a link between movement and thinking about movement. The experimenters fed back the sensation of walking to a pressure pad on the patient’s forearm, and used a VR avatar, to help give the patient the illusion of walking, and then the distinctive sensations of walking over grass or sand.
Gradually, and at different rates, they began to experience voluntary muscle function below the injury. They went from a total absence of touch sensation to the capacity to sense pain, pressure and vibration, though not temperature. Gastrointestinal function improved, and those who spent most time upright and walking saw the most improvement in bowel control. Men reported experiencing erections. All had been diagnosed as cases of complete paralysis. Since the training, some of them have now been reclassified as partially paralysed.
None yet can walk unaided, but one has progressed to walking – without any help from a therapist – with crutches and braces from hip to ankle to support the legs. The research paper describes results after the first 10 months of the study. But the training continues, and there is more yet to be published.
“We are already thinking about ways of disseminating this protocol with more affordable technology,” Nicolelis said.
“If you remember your first cellphone, it looked like a brick, and now I am talking to you from a tiny little cellphone in Brazil, so things have evolved very quickly. I think that at the moment we can show clinical benefits. There are about 25 million people in the world paralysed just with spinal cord injuries and when you receive a diagnosis of being a complete paraplegic people usually don’t do anything any more to you. They just try to get you adapted to life in a wheelchair.”