Brain-Machine Interface Helps Paraplegic Patients Walk Again

A young paralyzed man from Brazil delivered the opening kickoff of 2014 FIFA World Cup opening ceremony. He used a brain-machine interface that allowed him to control the movements of a lower-limb robotic exoskeleton.

This was the work of the Walk Again Project (WAP), a nonprofit, international research consortium. Two years after the demonstration, the WAP has released its first clinical report.

‘The long-term use of brain-machine interface could lead to a significant recovery of neurological function in patients suffering from severe spinal cord injuries.’

A group of patients who trained throughout 2014 with WAP's brain controlled system, including a motorized exoskeleton have regained the ability to voluntarily move their leg muscles and to feel touch and pain in their paralyzed limbs. The patients also regained degrees of bladder and bowel control and improved cardiovascular function, which in one case resulted in a reduction in hypertension.

The study is the first to report that long-term use of brain-machine could lead to the significant recovery of neurological function in patients suffering from severe spinal cord injuries.

The long-term use of brain-machine promoted brain reorganization and activated dormant nerves that may have survived the original spinal injury from 3 to 14 years earlier.

The researchers were led by neuroscientist Miguel Nicolelis, director of the Duke University Center for Neuroengineering and president of the Alberto Santos Dumont Association for Research Support.

The researchers said that they do not yet know the limits of this clinical recovery, since patients have continued to improve since the World Cup demo. They hope that their initial findings could influence future clinical practices for paraplegic patients by upgrading brain-machine interfaces from a simple assistive technology to a potential new therapy for spinal cord injury rehabilitation.

Alan Rudolph, vice president for research at Colorado State University, who is also an adjunct faculty member at Duke University's Center for Neuroengineering, led a brain-machine interface research effort starting in 1998 that helped the Duke neuroengineers develop pre-clinical demonstrations. These efforts led to the human clinical trials in the Walk Again Project.

"This has been a tremendous journey, to start working on this phenomenal project over 15 years ago on ideas first demonstrated in animals, and that are now showing revolutionary theories of how the brain works," Rudolph said. "The WAP scientists are making a real impact in helping impaired people walk again. Seeing faces of young adults walking for the first time in many years has been life-changing for all of us."

No clinical study that has used brain-machine in patients suffering severe spinal cord injuries reported any neurological improvements. The author noted that it could be because those studies involved only one subject and for a shorter period of time.

The researchers trained eight paraplegic patients for a year on what they call the Walk Again Neurorehabilitation protocol. Out of eight, seven patients had complete injury, according to the American Spinal Injury Association (ASIA) Impairment Scale, and one was classified with an incomplete injury.

The brain-machine interface consisted of multiple EEG recording electrodes embedded in a cap on the patient's scalp, fitted over the brain areas controlling movement in the frontal lobe.

The patients wearing an Oculus Rift head-mounted display were shown a three-dimensional avatar of a person, and were asked to imagine movements of their own bodies so they could make the avatar walk. All patients learned to use only their brain activity to move the avatar.

Every time the avatar's feet touched the ground, the patients received a continuous stream of tactile feedback, which was delivered through mechano-vibrating elements in a long-sleeved "tactile shirt."

For the second component, the patients also used a Lokomat, a robotic gait orthosis placed on a treadmill, which enabled them to perform walking motions while suspended by a harness. In a third component, the patients operated a brain-controlled motorized exoskeleton custom designed for the project. The exoskeleton is the same one demonstrated at the 2014 World Cup.

The combination of visual and haptic feedback was critical to the training paradigm, Nicolelis said. "The addition of tactile feedback that was coherent with the visual feedback created a very realistic walking illusion for the patients when they controlled a virtual avatar or the robotic exoskeleton."

Importantly, Nicolelis said, the researchers saw significant changes in the EEG patterns in the patients' brains. In the spinal cord, the combination of brain reorganization and muscle exercise may have also induced sprouting of new connections, the researchers theorized.

The researchers hope to take their protocol to other spinal cord centers around the world, to replicate and expand on these initial findings.

"Currently, once people with spinal injuries receive a diagnosis of complete paralysis, rehabilitation consists mainly of adapting them to a wheelchair," Nicolelis said. "We believe that our results with this long-term, sustained brain-machine interface training can be not only critical itself in triggering a recovery in our patients, but it can also serve as an important motivator for spinal cord patients worldwide."

The study is published in Scientific Reports.

Source: Medindia