The first step
Scientists have restored the ability to walk to three paralytics
For the first time, Swiss neurophysiologists were able to restore leg mobility to three people with an old spinal fracture, "pointwise" stimulating the work of a damaged fragment of the spinal cord. The results of the experiment were presented in the journals Nature (Wagner et al., Targeted neurotechnology restores walking in humans with spinal cord injury) and Nature Medicine (Formento et al., Electrical spinal cord stimulation must preserve proprioception to enable locomotion in humans with spinal cord injury).
"Our success is based on a very deep understanding of how the mechanisms that control the movement of limbs in rats and other animals work. Thanks to past experiments, we were able to simulate in real time the impulses that the brain sends to the damaged part of the spine and take the first step towards a complete cure of paralysis," said Gregoire Courtine, a neurophysiologist from Higher Polytechnic School in Lausanne (in the press release Breakthrough neurotechnology for treating paralysis – VM).
The power of thought
Damage to the spine leads to partial or complete paralysis of the limbs, depending on the location of the injury. To date, scientists are developing several methods of treating such injuries. Many biologists are trying to use stem cells to reconnect between parts of the spinal cord. There are also fundamentally different methods – connecting the limbs to the brain using electrodes.
Kurtin and his colleagues, including Russian neurophysiologists from the Pavlov Institute of Physiology of the Russian Academy of Sciences in In St. Petersburg, several years ago, an original technique was developed that allows to restore freedom of movement to paralyzed rats without surgical intervention and injections of stem cells.
They drew attention to the fact that even with the most serious spinal cord injuries, some of the nerve fibers remain intact. These chains of neurons are not involved in the work of the body's motor system, but they can be "switched" to a new task.
Subsequent experiments showed that electrostimulation of these neurons using a set of electrodes, as well as special training in a special "exoskeleton" allowed rats and macaques to almost completely restore the mobility of their legs after partial cutting of their spine.
Today, Kurtin and his colleagues have published the results of the first experiments of this kind, which they conducted on three volunteers from the Netherlands and Switzerland who lost the ability to walk about 4-5 years ago as a result of an accident or accidents during sports.
Having located the point where their spinal cord was damaged, the scientists began to conduct the same series of exercises and experiments with volunteers as with animals. They suspended them in an exoskeleton, asked them to imagine that they were walking on a treadmill, and recorded the signals produced by the brain.
After implanting the electrodes, Curtin and his colleagues began sending these signals to the spinal cord of patients, bending and unbending their legs while "jogging" along the same path. Just a week later, the volunteers learned to stand on their own and take automatic steps, and after 2-3 weeks, they began to make arbitrary movements with their feet.
"The doctors told me that I would never be able to walk. Now I can independently overcome small distances both with the help of a stimulator and crutches, and without them. My muscles have become much stronger. Now I have hope that I will be able to barbecue at the dacha again," Gert–Jan Oskam, one of the participants in the experiments, shares his impressions.
After about five months of training, as Kurtin notes, all his wards learned to walk on a treadmill in an "exoskeleton" on their own, without needing external support for many hours and kilometers. Two of them can now move independently even without the help of a stimulator.
A world of equal opportunities
"My former colleagues and teachers, Kendall Lee and Reggie Edgerton, recently conducted a similar experiment using the simplest forms of constant nerve stimulation. Such techniques require very long and exhausting training – they spent almost a year trying to teach the patient how to walk, using the help of two other people. We put our three wards on their feet in just two or three weeks," Kurtin said in an interview with RIA Novosti.
In addition to rapid recovery, the "point" stimulation of the spinal cord, as explained by the scientist and the participants of the experiments themselves, has many other advantages. Such an approach, as explained by David Mzee, another volunteer, does not cause a feeling of "stiffening" of the legs, as constant stimulation of the damaged part of the spine, and allows them to spend less energy on making movements.
In addition, some improvements in the patients' ability to move independently persisted even after the scientists turned off the stimulator after the departure of David, Jan and Sebastian, the third participant in the experiments, from the laboratory. Now all patients independently continue to exercise at home, using special tablet apps that scientists have written for them.
As Kurtin noted, many of his "competitors" and former colleagues will soon join him and Jocelyn Bloch, a neurosurgeon from the University of Lausanne Hospital, as part of the GTX medical startup, created specifically to further improve this technology.
"In the past, we used a kind of analogue of deep brain stimulation systems used in the fight against Parkinson's disease and some other diseases. They work quite efficiently, but do not differ in high accuracy. The next version of our technology, which we will develop in our startup, will use really "point" implantation of electrodes, which will dramatically increase the speed of muscle response to commands and the possible repertoire of movements," the scientist explained.
As Kurtin stressed, one should not expect a miracle and a complete cure for absolutely all paralytics. If the patient has experienced a complete rupture of the spinal cord, and there are no "whole" fibers left in it, then using such a stimulation system, he will not be able to walk on his own.
Another important requirement is that the paralytic must have a "sixth sense" and feel the touch of his feet in order for this technique to work. Otherwise, he will not feel where his limbs are during training, which will deprive them of meaning and will not allow him to stand on his feet.
"In the best case, we will be able to make such patients stand during such stimulation and perform "robotic", automatic movements. This can be done in the laboratory, but there is no sense from such achievements in everyday life. We need to look for some other ways," the scientist concluded.
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