Researchers from the University of California, Irvine, successfully created a system of artificial electrical signals to circumnavigate a paraplegic man’s spinal injury. The man’s name undisclosed for privacy reasons. As a result, the 26-year-old was able to walk for the first time in five years, making him the first paraplegic to walk without relying on manually-controlled robotic limbs.
Published in the Journal of Neuroengineering and Rehabilitation this September, the work used Functional Electrical Stimulation (FES)—a system that sends electrical signals to nerves innervating damaged areas like muscles—to give the man control of his legs.
“The concept of Functional Electrical Stimulation (FES) has been around for probably 40 years,” explained McGill Neurology Professor Samuel David. “What they have done [in this study] is taken FES to the next level. There’s still electrical stimulation like you would have in [normal] FES, but here the patient can initiate the signals [themself].”
FES signals were read and understood by a computer, a process called a Brain Computer Interface (BCI). In order to use this technology, the patient had to generate recognizable ‘walking’ signals in his brain, which would then be picked up by the computer.
“The person has to consciously think to walk,” David explained. “Usually when we walk and talk, we don’t think about walking. But [in the patient’s case], if they don’t think [about walking,] they won’t be able to walk.”
To practice making these signals, the patient first worked in a virtual environment. Then, he practised walking while suspended five centimeters above the ground. Following a 19 week-long process, with help from a walker and harness, the patient was finally able to walk a distance of about four metres.
During the entire process, the patient had to wear a cap with a built-in Electroencephalogram (EEG). The EEG read his brain waves and transmitted them to a computer system that interpreted them as signals to either rest or walk.
“What [the researchers] are doing essentially is collecting the electrical activity from the skull and [introducing it] to the computer that triggers a pre-programmed software,” David said.
The computer turns on an electrical stimulator that creates alternating muscle contractions in either one of his legs, making the person walk. When the thoughts stop, so does the walking. The beauty of technology like this is that it can bypass damaged areas—like the spine—and directly reach a target muscle and stimulate a nerve reaction.
“Once we’ve confirmed the usability of this noninvasive system, we can look into [more] invasive means, such as brain implants,” explained Dr. Zoran Nenadic, the lead researcher on the study to ScienceDaily. “We hope that an implant could achieve an even greater level of prosthesis control because brain waves are recorded with higher quality. In addition, such an implant could deliver sensation back to the brain, enabling the user to feel their legs.”
Some issues still need to be addressed, however, before this type of technology is accessible to a larger audience. In laboratory tests, the computer mixed up signals for balance and stabilization with walking.
“Even though they say ‘walking,’ the person still [does not have the] ability to balance, which is why they used a harness during the trial,” explained David. “So, electrical stimulation is being sent to the muscles, but there’s no proprioceptive feedback yet and you can’t have balance.”
More research needs to be done before this type of technology can be accessible to more patients, but it’s a step in the right direction.
“You’re not really solving the biological problem, but it doesn’t mean it’s not good,” said David. “To help people with neurological conditions, we have to approach the problem in all sorts of ways.”
