For Bill Kochevar, paralysed from the neck down for eight years after a cycling accident, it was a personal triumph. Using his own arm and hand, he scooped forkfuls of mashed potato from a bowl into his mouth.
For the team of biomedical engineers at Case Western Reserve University in Cleveland, Ohio, Mr Kochevar’s restored ability to feed himself was a milestone in neurotechnology. He was the world’s first quadriplegic patient to regain some limb movement electronically, using a brain implant that enabled him to reanimate long-dormant muscles through the power of thought.
Details of Mr Kochevar’s rehabilitation are published in the Lancet. “This study demonstrates for the first time the feasibility of bridging a spinal cord injury and restoring some independence to someone with quadriplegia,” Bob Kirsch, the project leader, told the FT. “Now we can look forward to further development of the technology.”
The Cleveland study brings together two components of neurotechnology that have shown great promise individually. One is a brain-computer interface that translates thoughts into computer signals. Mr Kochevar’s Braingate2 implant consists of two 96-channel electrode arrays, each the size of a small pill, placed on the surface of the motor cortex that controls movement. Similar devices have enabled paralysed patients to move robotic arms and operate computer keyboards through their thoughts.
The other part of the system involves functional electrical stimulation (FES) of the arm and hand. FES, which activates paralysed muscles with small pulses of electricity, is used extensively to restore or improve mobility in disabled people. However, it has not previously been controlled directly by the user’s own brain.
The team had to prepare Mr Kochevar, 56, gradually to use the system. First he worked with Braingate2 linked to a computer, learning to move a virtual reality arm by thinking about moving his real arm. After four months training, the researchers felt he was ready to control his own limb, so they implanted 36 FES electrodes along his right arm from shoulder to hand.
He could not get going immediately because the muscles had atrophied after years of inactivity. The scientists exercised Mr Kochevar’s arm and hand with electrical stimulation over the course of a year. As his range of movements improved, he gained the ability to scratch an itch on his nose with a dry sponge, grab a cup of water and drink from it through a straw, and then — his top goal — eat without assistance.
Now he can make each joint move individually. If he thinks about drinking or feeding himself, the muscles are activated in a co-ordinated way. When the researchers asked him how he commanded the movements in his arm, he replied: “I’m making it move without having to really concentrate hard at it. I just think ‘out’ and it just goes.”
“For somebody who’s been injured eight years and couldn’t move, being able to move just that little bit is awesome,” Mr Kochevar added.
Steve Perlmutter, a neurotechnologist at the University of Washington who was not involved in the project, commented: “The study is groundbreaking, as the first report of a person executing functional, multi-joint movements of a paralysed limb with a motor neuro-prosthesis. However, this treatment is not nearly ready for use outside the lab.”
Mr Kochevar’s arm movements are slower and more restricted than a limb working naturally on an able-bodied person. He also needs to keep looking at an object to grasp it accurately.
Professor Kirsch readily conceded that the technology has a long way to go before people can use it reliably at home. “We needed to make the system affordable and reversible for this clinical trial, using a temporarily implanted FES system that could be removed if necessary,” he said. A permanent implant would give better results.
Future improvements might include providing a wireless connection to the brain implant and developing better computer programmes to translate thoughts into more precise movements.
Benjamin Walter, clinical leader of the Cleveland trial, said: “By restoring the communication of the ‘will to move’ from the brain directly to the body, this work will hopefully begin to restore the hope of millions of paralysed individuals that, some day, they will be able to move freely again.”
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