Beneath the lesion, researchers from the universities of Pittsburgh and Carnegie Mellon write in Nature Medicine“spinal circuits that control movement remain intact and might be targeted by neurotechnology to restore movement.”
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The researchers used implants already used in the treatment of chronic pain. Electrodes placed on the surface of the spinal cord send electrical impulses to the nerves responsible for controlling the arm and hand. This has the effect of amplifying signals that originate in the brain, but have now become too weak to be effective.
“The big first is really to use these stimulations for strokes,” said Marina Martinez, who is a regular researcher at the Hôpital du Sacré-Coeur-de-Montréal and professor in the department of neurosciences at the ‘Montreal university.
“In reality, we simulate the spinal cord for injuries that take place in distant structures, in particular the brain. So that’s where it’s really something quite new.”
Progress in four weeks following a stroke
After four weeks, improvements had been seen in muscle strength, dexterity and range of motion. One treated patient, for example, was able to perform such delicate tasks as turning a key in a lock or cutting her food with a hand that had previously been unusable.
We usually hear regarding such advances when it comes to restoring movement to the lower extremities of patients who have suffered spinal injuries. Achieving the same feat following a stroke by targeting the upper limbs is a much more complex task, not least because of the number of nerves that need to be stimulated to cause movement.
“Some mechanisms are quite similar to spinal cord injury, but others are not,” commented Ms Martinez, who also runs her own lab specializing in understanding the neural basis of sensorimotor recovery in animal models of spinal cord injury. medullary damage.
Instead of a spinal cord injury that interrupts the signals between the brain and the body, she said, we are talking here regarding an injury that occurred directly to the brain.
The effect of the implants, however, is temporary and ceases as soon as they are removed, although the researchers report in their study that the patients retained “some improvements even without stimulation”.
For the moment, this is a very interesting avenue to explore in the context of the rehabilitation of these patients, believes Ms. Martinez.
The idea, she said, is not to “leave them on stimulation for life.” Rather, the aim is to obtain long-term beneficial effects “on the mechanisms that allow motor compensation” when the stimulation is stopped.
When the patient has suffered an incomplete injury and residual pathways persist between the brain and the spinal cord, said the researcher, these stimulations can make it possible to “recruit these pathways to allow (the patient) to reorganize over a long period of time. term”.
She considers that the same strategy might one day be used in the treatment of other neurological traumas, such as concussions.
“I think it’s a very promising avenue to try to target these recovery mechanisms there,” concluded Ms. Martinez.
