Robotic exoskeletons have help paralysed people walk in the past, by both supporting and controlling their legs. But for the first time, a robotic exoskeleton has been paired with spinal stimulation to help a paralysed person walk using his own muscles.
Mark Pollock had lost his sight in 1998 and subsequently went on to become an athlete, competing in endurance races across a variety of terrain. He was the first blind man to race to the South Pole, and won medals for Northern Ireland in the Commonwealth Rowing Championships.
In 2010, Pollock fell from a second-story window. He broke his spine, which left him paralysed from the waist down.
For four years, Pollock was unable to walk. Then, a team of scientists at the University of California, Los Angeles devised a system that, after five days of training, allowed Pollock to take thousands of steps in the following two weeks, with full control of his own muscles. It is, the team says, the first time a person with chronic, complete paralysis has been able to do so. The research was published by the IEEE Engineering in Medicine and Biology Society.
The system consists of a battery-powered robotic exo-suit and non-invasive spinal stimulation. The stimulation had previously been tested on five men with paralysis, and they had regained the ability to voluntarily control their muscles. This indicated that the neural connection to those muscles could be revived with precise electrical currents.
Those men, however, were not able to bear their own weight on their newly mobile legs. Adding the robotic exoskeleton was the next step in the research, allowing Pollock to stand on his own feet with the exoskeleton providing support. Then, thanks to the spinal stimulation, Pollock was able to move his legs to take steps.
This not only restored his mobility, but also increased his cardiovascular function and improved his muscle tone, the researchers said.
"In the last few weeks of the trial, my heart rate hit 138 beats per minute," Pollock said. "This is an aerobic training zone, a rate I haven't even come close to since being paralysed while walking in the robot alone, without these interventions. That was a very exciting, emotional moment for me, having spent my whole adult life before breaking my back as an athlete."
The exoskeleton included a robotic module that was able to determine exactly how much the patient is relying on the robotic suit, and how much they are using their own muscles. Using this data, the team was able to determine that Pollock was actively flexing his left knee and lifting his left leg during and after spinal stimulation.
"For people who are severely injured but not completely paralysed, there's every reason to believe that they will have the opportunity to use these types of interventions to further improve their level of function. They're likely to improve even more," said V. Reggie Edgerton, senior author and UCLA distinguished professor of integrative biology and physiology, neurobiology and neurosurgery.
Whether or not the procedure will be able to assist in restoring full mobility is unknown at this point, and the resources are years away from being widely available. However, the team is hopeful that, in the future, the research will help completely paralysed patients regain at least partial mobility.
"It will be difficult to get people with complete paralysis to walk completely independently, but even if they don't accomplish that, the fact they can assist themselves in walking will greatly improve their overall health and quality of life," Edgerton said.