Three paraplegics walk again thanks to a small electronic implant | Science



David Mzee gets up and walks, in a photographic composition.

The Swiss David Mzee suffered an accident in 2010 while practicing sports, when he was only 20 years old. He remained paraplegic, with hardly any residual control of his right leg. However, last year, he got up and walked awkwardly a few steps, without help. "When I released the parallel bars, I felt almost as if I were walking normal. I want to train more to see where we can go, "he explains now in a teleconference for the international press.

The apparent miracle is just a new scientific technique, which first demonstrated its success in rats in 2014, which later worked in monkeys in 2016 and that now reaches humans. A team led by the neuroscientist Grégoire Courtine, from the Federal Polytechnic School of Lausanne (Switzerland), and the neurosurgeon Jocelyne Bloch, from the university hospital in the same city, has implanted electrodes in the lumbar spinal cord of Mzee and two other paraplegic patients: the Dutchman Gert-Jan Oskam, 35, and the Swiss Sebastian Tobler, 47 years old. This epidural electrical stimulation, combined with almost daily rehabilitation sessions for five months, has made the three begin to walk again, with the help of crutches or a walker.

All three patients have regained voluntary control of their leg muscles, even without electrical stimulation

Only a week after starting the exercises, David Mzee took a first step. "It was impressive," recalls the young Mexican engineer Ismael Seáñez, co-author of the investigation. Unlike two similar studies presented in September by two other US scientific groups, the Swiss team does not stimulate the spinal cord continuously, but, thanks to sensors on the feet of patients, a computer program sends electrical pulses that They try to facilitate residual voluntary movements by mimicking the natural electrical signals of the brain. The stimulation is carried out "with the precision of a Swiss watch", in the words of Courtine.

The Spanish neuroengineer Eduardo Martín Moraud participated in the experiments on rats and monkeys. "Electrical stimulation is done at the right place and at the right time. And this facilitates the reactivation of the nervous connections that remain in the injured spinal cord ", underlines the scientist, from the University Hospital of Lausanne. The three patients, after five months of sessions, have recovered to a greater or lesser extent the voluntary control of their leg muscles, even without electrical stimulation. The results of the research are published simultaneously in the journals Nature Y Nature Neuroscience.

Sebastian Tobler fell off the bike in 2013 and his legs were totally paralyzed. His doctors did not give him much hope, but he himself built a kind of tricycle with which to do recumbent exercises, pedaling with his hands. The clinical trial of Lausanne has changed his life. "After five days I could walk [con apoyos y la estimulación eléctrica de precisión]. Do not walk a few steps after a year of training, but a kilometer after a few weeks, "says Courtine.

"It's great to walk in the laboratory, but it's not enough, there's still a lot to do", warns neuroscientist Grégoire Courtine

The French neuroscientist, however, is cautious. "It's great to walk in the laboratory, but it's not enough, there's still a lot to do," he admits. Courtine has created the company GTX medical to develop a simple device that allows patients to carry out rehabilitation anywhere, away from a hospital.

On September 24, the team of neuroscientist Kristin Zhao at the Mayo Clinic in Rochester (USA) announced that a 29-year-old man - who became paraplegic in 2013 after an accident on a snowmobile - He was able to walk 100 meters with the help of a walker and continuous electrical stimulation in his spinal cord, after more than 25 weeks of sessions. The same September 24, the group of neurosurgeon Susan Harkema, of the University of Louisville (USA), published that two of his paraplegic patients had achieved walk a few steps after 15 and 85 weeks of rehabilitation sessions and continuous electrical stimulation.

"The new study is important because it confirms that people with chronic spinal cord injury have the ability to recover by retraining the circuits of the spine. [El grupo de Courtine y Bloch y nosotros] we use somewhat different approaches, but human circuits are smart enough to respond to both! "Harkema applauds. "We need more research and more clinical trials to know what kind of stimulation and training are necessary to obtain the best results," he warns.

Neuroscientist Kristin Zhao is also cautious. "The number of patients in the scientific literature is still very small. In addition, the long-term efficacy and safety of these technologies in humans have yet to be confirmed, "he says.

All three studies show that one must stop seeing spinal cord injuries as an insurmountable barrier between the brain and the muscles. The reactivation of the nerve connections - after intensive sessions of rehabilitation exercises with epidural electrical stimulation - suggests that the spinal cord can be recovered. Courtine believes that now it is scientists who have to keep walking: "The new studies, together, show a potential treatment for spinal cord injuries. Now the essential thing is to concentrate on the following steps ".

"The next step is to start before"

The French researcher Grégoire Courtine recognizes that his scientific "father" is Reggie Edgerton, pioneer of epidural electrical stimulation at the University of California at Los Angeles (USA). In 2009, the American made paraplegic rats take a few steps thanks to electrical impulses in his injured spinal cord. In 2014, he got four paraplegic men to voluntarily move his ankles and toes.

Courtine believes that her main contribution to Edgerton's work has been to "understand the science behind this." The new device they have tested now is self-modulated in real time and synchronizes the electrical pulses to the rudimentary voluntary movements of the patients. Courtine's team is convinced that this new strategy is the key. "The next step is to start before, immediately after the spinal injury occurs, when the potential for recovery is much greater," explains neurosurgeon Jocelyne Bloch. Courtine, however, insists on his call for caution: "At this point of the investigation we must calibrate the expectations. At the moment, what we have is a proof of concept. "

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