2023-05-29 21:08:36
Thanks to technologies developed in partnership with the CEA of Grenoble, a university hospital team from Lausanne (Switzerland) developed and implanted a brain-spinal interface in a 40-year-old quadriplegic man, Gert-Jan Oskam, and allowed to walk once more [1].
This world first, which rightly caused a stir, follows the evolution of a first Swiss neurostimulator which, in 2018, enabled several patients with spinal cord injury to walk, including this same subject. [2] : this spinal implant made it possible to administer epidural electrical stimulation targeting the different entry zones of the dorsal root at the lumbosacral level. But the stimulation sequences were pre-programmed: if they made it possible to re-establish the upright posture and the walking movement, they were not adapted to the intentionality of the subject or to the walking terrain.
This is where the teams from Grenoble (Clinatec/CEA biomedical research center) come in, who have been developing the WIMAGINE® device for ten years: this medical device made up of 64 electrodes makes it possible to measure and transmit electrocorticograms in real time. (EcoG) of a patient and transfer them to an artificial intelligence algorithm (machine learning) to translate them into movement through the use of an exoskeleton. EcoG data is transferred to a computer placed in a backpack. In 2017, this device was implanted in the cranium of a 27-year-old tetraplegic subject, next to the upper sensorimotor areas [3]. The latter, through training in piloting virtual environments, was able to gradually control the exoskeleton to chain a few steps and control his upper limbs.
Natural walking restored
It was therefore the combination of these two technologies that made the headlines last week: by combining the two approaches, this “digital bridge” made it possible to transfer the information collected at the cortical level to the spinal neurostimulation device and to thus restoring communication between the brain and the region of the spinal cord controlling the movement of the legs. This interface combines the cortical signal recording system and the analog modulation of epidural electrical stimulation targeting the regions of the spinal cord involved in the production of walking.
This medical success was the subject of a publication in the journal Nature [1] which reports: from the first session following the neurosurgical intervention, the algorithm calibrated the interface to allow the participant to control the relative flexion of the left and right hips of an avatar projected on a screen.” They then applied this decoding to spinal cord stimulation. “While lying down, the participant was able, in less than two minutes, to control hip muscle activity to generate torque with 97% accuracy. “. When expanded to the hip, knee and ankle joints, ” the participant managed to progressively control the movement of each bilateral joint with an accuracy of 74 ± 7%, while the level of chance was limited to 14% with low latency (1.1 seconds). The combination of the two approaches allows the patient to decide whether to initiate, maintain or stop walking. It also remedies his ability to adapt his step to the terrain. Note that one of the implants had to be removed due to a subcutaneous infection Staphylococcus aureus. He was replaced following treatment and recovery of the patient.
As the journal Nature reports [4]this work shows that even if it is a long-term chronic injury, healing can still take place“. In the world [5]Grégoire Courtine confides that“With the previous program, we had already seen that a large majority of patients recovered lost neurological functions following their accident, but this interface seems to further increase neurological recovery. This suggests a regrowth and reorganization of the nerve fibers involved in walking, but also a form of collaboration between the digital bridge and the natural nerve bridge. » The Swiss team will now initiate new studies to extend this proof of concept to a larger cohort, and are currently recruiting three people to assess whether a similar device can restore arm movement. For their part, the Grenoble team is working on a transition to an electronic chip, a miniaturized version of the laptop computer. Other applications, such as bladder or bowel control, might also be targeted by this type of device.
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