Phantom limb painful syndrome is a physiological condition that occurs in about 85% of amputee patients. It is the sensation of pain in a part of the body that has been removed in a traumatic or congenital way. One of the most effective techniques for the treatment of pain is spinal cord stimulation, its effectiveness rate varies from 50 to 70%.
Two separate teams, the University of Louisville Spinal Injury Research Center and the Mayo Clinic in Rochester, Minnesota, revealed in Nature Medicine and the New England Journal of Medicine that the device, in conjunction with physical training, has enabled patients with complete spinal cord injury could recover voluntary movements.
The device consisting of two components, a neurostimulator and a plate from a set coated with 16 electrodes, was inserted below the injury site, activating regions that capture lost sensorimotor signals emitted by the brain, amplify them and redirect them to the tissue of the spinal cord. It is connected to a battery implanted in the abdominal wall, and its stimulation frequency, intensity, and duration can be adjusted wirelessly. The electrical activity produced by the leg muscles was monitored during the sessions.
Epidural stimulation works based on the principle that there are still some small signals from the brain that cross the spinal cord injury site, but by themselves, they are not enough to generate voluntary movements. The spinal cord can signal that the muscles move, regardless of the brain's commands. It is like the chicken that continues to run, even after its head has been cut off.
“We know that the spinal cord has the ability to organize motor activities in detail”, says Dr. Claudia Angeli co-author of one of the studies at the Kentucky Spinal Cord Injury Research Center. "Before the injury, the spinal cord received commands from the brain and information from the environment," she says, the injury interrupts this communication. "The spinal cord is isolated, potentially still receiving information from the environment, but it has lost the great conductor, which is the brain". Claudia added that physical training to link movements with these signals is crucial.
In the published study, Angeli and her colleagues reported that the device was implanted in four people paralyzed years ago, after suffering traffic accidents or mountain biking. All of them lost all motor control below the injury site, but two showed some level of sensitivity. After implanting the device and locomotor training, two were able to walk on the ground without help and all recovered some movement.
Kelly Thomas, a 23-year-old from Florida who lost her movements in a car accident, was able to walk with the aid of a walker, after 81 stimulation sessions for 15 weeks, and said: "Being a participant in this study really changed my life, as it gave me hope that I didn't think was possible after my car accident." Jeff Marquis, 35, who lost his movements on a mountain bike tour, also walked just over 90 meters without interruption after 278 sessions over 85 weeks. Now he can carry out his activities independently since he needed a helper to get him out of his bed every morning, "I can do this alone now" says Jeff. The other two people were able to stand and sit independently, one of them was able to walk a few steps on the mat with support as reinforcement.
The Mayo Clinic team led by neurosurgeon Dr. Kendall Lee, obtained similar results using the same procedure. According to the published study, Jered Chinnock, 29, who had his spinal cord cut and was paralyzed after a snowmobile accident, walked again with assistance to maintain his balance after 43 weeks of treatment.
"The patient's own mind, or thought, was able to drive the movement of the legs," said Dr. Kendall Lee emphasizing that much of the mechanism remains unknown. “You need to provide a very specific type of stimulation parameters. Random stimulation does not work ”. Programming the device to give better results takes time and to achieve a good balance, it is necessary to correctly attune the stimulation intensity and although the device recovers the voluntary movements it does not restore the sensation of the removed organs.
"Our results, combined with previous evidence, emphasize the need to reevaluate our current understanding of spinal cord injury in order to realize the potential of emerging technologies for functional recovery since it was thought to be permanently lost," said Lee.
According to Angeli, there are hopes that the approach can help with more than leg movement. Angeli also states that the next step is to analyze the possibilities of performing this epidural stimulation in the bladder, thus improving your control.
Mike Milner, CEO of the Nicholls Spinal Injury Foundation, says that while the research looked promising, the charity supports another type of approach to combat spinal cord injuries using special cells taken from the patient's nose, as well as nerve fibers, to correct the injury.
"We are looking for not just a natural or biological cure for paralysis - but a permanent cure," he said.