The implant device has allowed three men with partly crushed spinal cords to regain some walking abilities after a few weeks of training. But the approach wouldn’t work for anyone whose spine has been completely severed.
Many people who are paralysed from a crush injury to their spine have a few nerves still connecting the brain to the legs, but not enough to allow walking.
A few such individuals have previously regained some lower body movement thanks to a spinal implant that electrically stimulates their spinal cord.
This makes the remaining nerves more excitable, and so amplifies the weak signals from their brain to their legs. But the improvements were only seen after gruelling training regimes that involved practising walking with the stimulation almost every day for nearly a year.
Grégoire Courtine of the Swiss Federal Institute of Technology in Lausanne, Switzerland, has upgraded the technique in two ways. His team uses more spinal electrodes, to individually target nerve bundles controlling several different leg muscles.
And the user has sensors on each leg, wirelessly communicating with these electrodes, so that whenever the limb begins to lift, it automatically triggers a short burst of stimulation.
Using this set-up while supported in a pulley has allowed three men to start recovering some walking abilities within a few days of beginning training. After several months, they can now walk around outside supported by wheeled walkers.
They also have better movement abilities even when the stimulators are turned off, says Courtine. Tests on rats suggest the precisely targeted stimulation encourages new nerve pathways to grow in the brain to better exploit the remaining nerves in the spine.
Source: News Scientist