For paralysis sufferers, there has in recent years been new hope, particularly in the form of a brain interface. In the past 12 months alone, we have seen great advances, with technology that intercepts and interprets the electrical activity of the brain, translating it into movement relayed to a robotic exosuit or prosthetic.
A new method devised by a team of researchers at the University of California, Irvine, however, removes the exosuit from the equation, transferring the signals directly to the patient's own limbs. Moreover, it does so non-invasively, using an electroencephalography cap worn on the head connected to electrodes on the limb.
In a proof-of-concept study, this system has for the very first time allowed a patient with complete paralysis in both legs to walk manually and independently, without the aid of robotics. The patient, who was paralysed after an accident five years ago, walked 3.66 metres (12 feet) on his own legs.
"Even after years of paralysis the brain can still generate robust brain waves that can be harnessed to enable basic walking," said, biomedical engineer Zoran Nenadic, one of the co-leaders of the study, along with neurologist An Do.
"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."
The system is not an automatic cure for paralysis. After so much time paralysed, the patient had to basically learn to walk again from scratch, a process that took months, and much of the effort was mental.
To be able to recognise the unique signals associated with walking produced by the patient's brain, he had to think about walking, wearing an EEG cap to capture his electrical brain activity. This data was then processed to isolate the brain activity associated with walking. This, in turn, was translated into signals that could be reliably relayed to a muscle.
The patient then had to learn how to use that information, controlling an avatar in a virtual reality simulation. This not only served as practice for the patient, but allowed the program to refine how it captured and relayed brain information.
Meanwhile, after years of inactivity, the patient's legs were in an atrophied condition, and he had to undergo extensive rehabilitation and physical therapy to strengthen his leg muscles to the point where they could bear his weight. Then, finally, he could be hooked up to the system, with the electrode cap capturing his brain activity, relaying it to electrodes attached to his knees.
He first practiced this suspended a few centimetres above the floor, so he could get used to controlling his own muscles. Then he did it, on the ground, partially bearing his own weight and aided by a walking frame and harness to help stay upright.
Now that the system is proven to work on one patient, the team will be working toward testing it with multiple patients, seeing if it is a feasible future therapy for paraplegia, and how it may be improved.
"Once we've confirmed the usability of this non-invasive system, we can look into invasive means, such as brain implants," said Do.
"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 his legs."
The team's research has been published this week in the Journal of Neuroengineering and Rehabilitation.