• Research Three paraplegics manage to move the trunk and legs thanks to spinal neurostimulation
  • Bioscience Nine people recover the mobility of their legs thanks to epidural electostimulation

In 2011, Dutchman Gert-Jan Oskam had a serious cycling accident in China. His spinal cord was badly damaged, with an incomplete injury that after much rehabilitation barely allowed him to move his arms.

From the beginning, his goal was to try to regain as much mobility as possible, so when he was told about a group of leading researchers from Lausanne (Switzerland) trying to find ways to help patients with spinal cord injuries, he did not hesitate to knock on his door.

He was one of five participants who took part in the STTIMO trial, a neurorehabilitation program that, through epidural electrical stimulation of the spinal cord, showed that it was possible to recover some motor ability. Thanks to the Oskam program, now 40, he was able to walk again with the help of a walker.

After three years, the Dutchman had reached the maximum possible recovery, so he also had no doubts when the multidisciplinary team led by Grégoire Courtine, from the Federal Polytechnic School of Lausanne (EPFL), and the neurosurgeon Jocelyne Bloch, from the University Hospital of Lausanne, proposed him to participate in a new trial, called STIMO-BSI, which wanted to go a step further in the approach.

The results of this strategy, which allows establishing a direct link between brain and spinal cord and provides a voluntary and more natural control of motor capacity, have meant a qualitative leap in Oskam's quality of life, as he pointed out at a press conference. You can perform tasks such as standing, walking, climbing stairs and adapting your gait to different terrains. The implantation of the device has also allowed him to improve neuronal recovery, so that he is now able to walk with crutches even when the implants are turned off. "These improvements are very useful in my day to day. They help me a lot," he said. Details of the case are published this week in the journal Nature.

What is the digital bridge that allows to recover motor function?

What the researchers have developed is a kind of 'digital bridge' that, to some extent, allows to restore the line of communication that exists between the brain and the area of the spinal cord that allows walking and that, in the case of Oskam, was damaged by the accident.

Through implants in the brain, the system is able to pick up cortical signals, the 'orders' that the brain sends when we want to stand up or take a step. These signals, duly decoded by artificial intelligence methods, are sent to a stimulation system implanted in the epidural region, where the generating center of the gait pattern is located, which allows the muscles involved to start according to the instructions received.

"It allows me much greater control. Now I control the stimulation with my thoughts," Oskam told reporters, a point Courtine also stressed.

Oskam walking through the park. Gilles WeberCHUV

Although it has given very good results, by itself the epidural electrical stimulation of the spinal cord that the team had previously used has some drawbacks, such as the fact that the patient must use a control or a button to start the stimulation or that it is difficult to adapt the movements to the changes in the terrain or to the needs of each task.

It allows me much greater control. Now I control the stimulation with my thoughts

This new direct connection between brain and marrow, on the other hand, allows more natural movements, adapted to each moment, since they occur in real time. In addition, it also allows a greater range of motion, for example, in hip flexion or knee extension, said the researchers, who want to extend the trial to more patients and explore the usefulness of the device in other cases, such as paralysis of the upper extremities.

"It is a very interesting work that follows the line that this team started more than 10 years ago," says Joan Vidal, rehabilitation doctor, teaching director of the Institut Guttmann in Barcelona and principal investigator of the research line 'Neurorepair and advanced therapies' of the aforementioned center.

Both the use of cortical receptors and epidural stimulation are techniques that had been used previously. The novelty is that this system combines them, providing voluntary control, "which is very interesting," says the specialist.

For Vidal, a highlight of the work is that it shows that after the implantation of the device and through rehabilitation, there is some functional recovery, the patient is able to walk again with crutches even when the implants are not connected.

"The central nervous system has a plastic capacity to generate new connections. And this again shows that through neuromodulation combined with neurorehabilitation these new neural networks that allow some recovery can be favored, "he says.

After turning off the system it seems that the patient is a little better, there is some functional recovery

Antonio Oliviero, head of the laboratory of functional exploration and neuromodulation of the nervous system of the National Hospital for Paraplegics of Toledo, pronounces, in the same line: "One of the data that most strikes me is that not only is there this possibility of walking when the stimulator and the interface are working but after turning off these systems it seems that the system is a little better, There is a certain functional recovery and this allows us to think not only of these devices as substitutes for anatomical and functional injury but also as important rehabilitation tools," he says.

In the future, the use of this type of device could also be considered in other types of motor disorders, such as those that occur after a stroke, both specialists agree.

"In the last 10 years, a lot of progress has been made. We are closer to understanding what are the lines of research where we must deepen, where we must invest, but there is still a way to go, "says Vidal, who asks for caution so as not to generate false expectations in patients. "This research has been carried out in a single patient," he stresses. The progress made is still limited and these types of devices still need more research before they can be approved by regulatory agencies, he recalls.

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