Washington, Sep 24 (PTI): In a first, a man who was completely paralysed in both legs due to spinal cord injury has been able to walk again using a system controlled by his brain waves, scientists say.

This is the first time that a person with complete paralysis in both legs (paraplegia) due to spinal cord injury was able to walk without relying on manually controlled robotic limbs, as with previous walking aid devices, researchers said.

The preliminary proof-of-concept study shows that it is possible to use direct brain control to get a person's legs to walk again, they said.

The participant, who had been paralysed for five years, walked along a 3.66m long course using an electroencephalogram (EEG) based system. The system takes electrical signals from the participant's brain, which then travel down to electrodes placed around his knees to create movement.

"Even after years of paralysis the brain can still generate robust brain waves that can be harnessed to enable basic walking," said Dr An Do, one of the lead researchers involved in the study, from University of California, Irvine.

"We showed that you can restore intuitive, brain-controlled walking after a complete spinal cord injury.

"This noninvasive system for leg muscle stimulation is a promising method and is an advance of our current brain-controlled systems that use virtual reality or a robotic exoskeleton," Do said.

Mental training was initially needed to reactivate the brain's walking ability. Seated and wearing an EEG cap to read his brainwaves, the participant trained to control an avatar in a virtual reality environment.

He also required physical training to recondition and strengthen his leg muscles.

The participant later practiced walking while suspended 5cm above ground, so he could freely move his legs without having to support himself. On his 20th visit, he translated these skills to walk on the ground and wore a body-weight support system for aid and to prevent falls.

Over the 19 week testing period, he gained more control and performed more tests per visit.

This proof-of-concept study involved a single patient so further studies are needed to establish whether these results are true for a larger population of individuals with paraplegia, researchers said.

"Once we've confirmed the usability of this noninvasive system, we can look into invasive means, such as brain implants," said Dr Zoran Nenadic, the senior lead researcher of the study, from University of California, Irvine.

"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," Nenadic said.

The research was published in the Journal of Neuro Engineering and Rehabilitation.