Paraplegics who have lost the use of the lower half of their bodies following car crashes, falls and other traumas have been able to regain feeling and movement in their legs after using virtual reality headsets and exoskeletons controlled by brain activity.
The Walk Again Project (WAP) is responsible for the life-changing work that saw several clinically diagnosed complete paraplegics – some of who had received their diagnosis a decade earlier– regain the ability to voluntarily move their leg muscles and to feel touch and pain in their paralyzed limbs.
“We couldn’t have predicted this surprising clinical outcome when we began the project,” said lead researcher and co-director of the Duke Center for Neuroengineering, Miguel Nicolelis.
“What we’re showing in this paper is that patients who used a brain-machine interface for a long period of time experienced improvements in motor behaviour, tactile sensations and visceral functions below the level of the spinal cord injury.”
“Until now, nobody has seen recovery of these functions in a patient so many years after being diagnosed with complete paralysis.”
Most of the patients involved in the study saw their condition upgraded from complete to partial paralysis.
To get participants to this point, researchers used a number of different tools to re-engage signals that go from the cortex to fibres in the spinal cord.
Patients wore caps embedded with multiple EEG recording electrodes to allow the researchers to see whether signals evident in motor control of the legs were present.
It appeared at first as though these signals had been lost, as the patients brains had completely erased all thought of their lower limbs, so virtual reality was used to get patients used to thinking about moving their legs again.
Wearing Oculus Rift head-mounted displays, the patients were asked to make a 3D avatar walk by imagining themselves making the same movement.
All patients learned to use only their brain activity, recorded through the EEG, to move the avatar’s body.
“Basically, the training reinserted the representation of lower limbs into the patients’ brains,” said Nicolelis.
Once signals between brain and muscles had been re-established, more challenging equipment was introduced that required patients to exert more control over their posture, balance and ability to use their upper limbs.
Having reestablished a connection between brain and spine, patients were asked to perform walking motions on a treadmill while suspended from a harness and then trained using a brain-controlled motorized exoskeleton.
During their training, the participants also wore a sleeve equipped with haptic feedback to enrich the experience.
“The tactile feedback is synchronized and the patient’s brain creates a feeling that they are walking by themselves, not with the assistance of devices,” Nicolelis said.
“It induces an illusion that they are feeling and moving their legs. Our theory is that by doing this, we induced plasticity not only at the cortical level, but also at the spinal cord.”
Following on from the study, which was published today in Scientific Reports, the researchers plan to create a new trial with patients who suffered more recent spinal cord injuries to see whether quicker treatment can lead to faster or better results.