During the 2014 FIFA World Cup opening ceremony, a Brazilian man paralyzed from the chest down delivered the opening kickoff, using a brain-machine interface that allowed him to control the movements of a lower-limb robotic exoskeleton.

Two years later, the researchers responsible for the demonstration—the Walk Again Project (WAP)—are reporting that a group of patients who trained throughout 2014 with the same 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. This, despite being originally diagnosed as having a clinically complete spinal cord injury—in some cases more than a decade earlier.

The patients also regained degrees of bladder and bowel control and improved their cardiovascular function, which in one case resulted in a reduction in hypertension.

WAP says theirs is the first study to report that long-term brain-machine interface use could lead to significant recovery of neurological function in patients suffering from severe spinal cord injuries. They theorize that the long-term training regimen likely promoted brain reorganization and activated dormant nerves that may have survived the original spinal injury from years earlier.

The researchers, led by neuroscientist Miguel Nicolelis, director of the Duke University Center for Neuroengineering, say they do not yet know the limits of this clinical recovery, since patients have continued to improve since the World Cup demo. However, they believe their initial findings could influence future clinical practices for patients with paraplegia by upgrading brain-machine interfaces—from a simple assistive technology to a potential new therapy for spinal cord injury rehabilitation.

In their recent work, the researchers trained eight people with paraplegia for a year on the Walk Again Neurorehabilitation protocol. Seven patients had been classified as having a complete injury 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. In a virtual-reality component of the rehab protocol, the patients wearing an Oculus Rift head-mounted display were shown a three-dimensional avatar of a person and 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.

They received a continuous stream of tactile feedback every time the avatar’s feet touched the ground. This feedback was delivered through mechano-vibrating elements in a long-sleeved “tactile shirt.”

For the second component of the WAP rehab protocol, the patients used a Lokomat, a robotic gait orthosis placed on a treadmill, which enabled them to perform walking motions while suspended by a harness. In this component, the patients used the same EEG cap to trigger the Lokomat movements while receiving tactile feedback.

In a third component, patients operated a brain-controlled motorized exoskeleton custom designed for the project—the same one demonstrated at the 2014 World Cup.

The combination of visual and haptic feedback was critical to the training paradigm, Nicolelis says. “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 says, 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 also have induced sprouting of new connections, the researchers theorize.

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