(CN) – A man who has been paralyzed from the shoulders down for eight years fed himself and drank coffee thanks to a new system that decodes brain signals.
Although only tested on one participant thus far, the new technology could represent a shift in how researchers approach treating paralysis, according to a study published Tuesday in the journal The Lancet.
The new study, which is the first to report results on a novel neuro-prosthetic, highlights how the system circumvents rather than repairs spinal injuries – meaning the user relies on the device being implanted and switched on to move.
“Our research is at an early stage,” said lead author Bolu Ajiboye, of Case Western Reserve University in Cleveland. “But we believe that this neuro-prosthesis could offer individuals with paralysis the possibility of regaining arm and hand functions to perform day-to-day activities, offering them greater independence.”
Ajiboye’s technology is the first to restore brain-controlled reaching and grasping in a person with complete paralysis.
“So far it has helped a man with tetraplegia to reach and grasp, meaning he could feed himself and drink. With further development, we believe the technology could give more accurate control, allowing a wider range of actions, which could begin to transform the lives of people living with paralysis,” Ajiboye said.
Previous research has used similar elements of the neuro-prosthetic, such as a brain-computer interface linked to electrodes on the skin that helped a person with less severe paralysis open and close his hand. Other advancements have enabled participants to control a robotic arm using their brain signals.
This is the first study to restore grasping and reaching in a person with a chronic spinal cord injury, using the system.
The patient, a 53-year-old man, underwent surgery to have the neuro-prosthetic fitted. The process involved brain surgery to place sensors in the motor cortex area of his brain responsible for hand movement, which created a brain-computer interface that learned which movements his brain signals were attempting to execute. This first stage took four months and included training using a virtual-reality arm.
Next, the team placed 36 muscle-stimulating electrodes into his upper and lower arm, four that helped restore wrist, elbow, shoulder, finger and thumb movements. The electrodes were switched on 17 days after the procedure and began stimulating the muscles for eight hours a week over 18 weeks to improve movement and strength and reduce muscle fatigue.
The researchers then wired the brain-computer interface to the electrical stimulators in his arm using a decoder – a mathematical algorithm – to translate his brain signals into commands for the electrodes in his arm.
Electrodes stimulated the muscles to produce contractions, which allowed the man to intuitively complete movements which he powered through thoughts. The system also involved an arm support to prevent gravity from simply pulling his arm down.
“It’s probably a good thing that I’m making it move without having to really concentrate hard at it,” the participant said of how he controlled the neuro-prosthetic. “I just think ‘out’ and it just goes.”
Twelve months after having the device fitted, the participant was asked to complete ordinary tasks including feeding himself and drinking a cup of coffee. He was observed as his arm completed an action under computer control, during which he thought about making the same movement so that the system could recognize the corresponding brain signals.
“Although similar systems have been used before, none of them have been as easy to adopt for day-to-day use and they have not been able to restore both reaching and grasping actions,” Ajiboye said.
At the time of the study, the participant had had the system implanted for nearly two years – 717 days – during which he experienced four minor adverse events that were treated and resolved.
Movements made using the system were also slower and less accurate than those made using the virtual-reality arm he used for training. While using the technology, he also needed to watch his arm as he lost his sense of proprioception – the ability to intuitively sense the position and movement of limbs – due to the paralysis.
“Our system builds on muscle-stimulating electrode technology that is already available and will continue to improve with the development of new fully implanted and wireless brain-computer interface systems,” Ajiboye said. “This could lead to enhanced performance of the neuro-prosthesis with better speed, precision and control.”
The technology is only approved for experimental use in the United States.
Writing in a linked comment, Steve Perlmutter, a University of Washington researcher who was not involved in the study, highlighted the promise of the technology.
“This study is groundbreaking as the first report of a person executing functional, multi-joint movements of a paralyzed limb with a motor neuro-prosthesis,” Perlmutter said. “The future of motor neuro-prosthetics to overcome paralysis is brighter.”