Using electrical stimulation, scientists at the Swiss Federal Institute for Technology (EPFL) have helped paralyzed rats with severed spinal cords walk again. And it might not be too long before this promising treatment starts to help people as human trials could begin as early as next summer. The study has been published in Science Translational Medicine.
Spinal cord injury is one of the leading causes of paralysis in the US, and the outlook for the vast majority of patients is depressingly bleak. The spinal cord is essential for movement because it acts as a middle man between the brain and the rest of the body; when it is injured, the flow of information to other body parts can be disrupted, resulting in the inability to move some or all limbs. Unfortunately, there is no effective treatment, so for many the paralysis is permanent.
But recently, there have been some encouraging developments in treatment as scientists figured out a way to mimic the brain signals required for movement by directly stimulating the spinal cord with electrical pulses. Remarkably, this experimental therapy allowed four paraplegic men to regain some voluntary movement in their hips, ankles and toes.
The problem with this technique, which is known as epidural electrical stimulation (EES), is that the amplitude and frequency of electrical pulses need to be constantly adjusted, which is difficult to achieve while an individual is attempting to walk. To overcome this limitation, EPFL researchers have developed algorithms that automatically adjust the pulses in real-time during locomotion, dramatically improving the control of movement.
For the study, the researchers used paralyzed rats whose spinal cords were completely severed. They surgically implanted electrodes into their spines and then placed them on a treadmill, supporting them with a robotic harness. After testing out different pulses and monitoring walking patterns, the researchers discovered that there was a relationship between how high the rat lifted its limbs and pulse frequency. Using this information, the researchers were able to develop an algorithm that constantly monitored the rats’ movement. This data was then fed back into the system which allowed automatic, rapid adjustments in the stimulation in real time, mimicking the way that neurons fire naturally.
The rats were able to walk 1,000 steps without failure and were even able to climb staircases. “We have complete control of the rat’s hind legs,” EPFL neuroscientist Grégoire Courtine said in a news release. “The rat has no voluntary control of its limbs, but the severed spinal cord can be reactivated and stimulated to perform natural walking.”
It is hoped that a human size version of the system could be used in robot-assisted rehabilitation, which may help patients with incomplete spinal cord injuries learn to walk again. The researchers will therefore test their scaled-up system, called Gait Platform, in human trials as early as next summer.
Check out a video from EPFL here: