For someone with leg paralysis, being able to walk again is a dream they have to let go of in order to be able to move on. But now science says they shouldn't have to live with that disability forever. In fact, there may be a way to help people paralyzed for a decade, walk again.
A recent study by the Kentucky Spinal Cord Injury Research Center at the University of Louisville conducted experiments with a small group of three paraplegic patients. Each of them had varying degrees of paralysis. Yet, with the help of a new technique, all three of them are now able to walk again at least to some extent, and that's improving further with physiotherapy.
Images courtesy: EPFL
The technique they used is called epidural electrical stimulation (EES), and it's not new at all, and has been investigated before as a way to treat paralysis. The difference instead here was with how it was applied.
Earlier EES experiments had patients taking months to make any progress, four months in the best case but mostly averaging close to a year. But this team of researchers, led by Gr¨¦goire Courtine and Jocelyne Bloch made ?breakthrough: they were able to walk with assistance only a few days after treatment.
With EES, a device is implanted into a person and it transmits electrical signals to the spinal cord. When someone is paralyzed, it's the result of an injury interrupting the connection between the brain and spinal cord, which the EES bridges. In rodents, cats, and monkeys, EES allowed the paralyzed animals to stand walk, and even run in some cases.
The problem with humans, the team posited, is that the signals were continuously transmitted, so there was no chance for the brain to receive feedback from the limb, meaning it didn't know where in space it was located. They suggested why it worked in rats has to do with how our physiologies differ.
What the researchers did then, was to study how the nervous system in a healthy person responds to movements in every joint. In this way they built an 'activation map' of how these signals are transmitted and returned as a person walks.
The team then placed electrodes in a paraplegic patient according to that map, so they could mimic the patterns using a custom-built system. The results were undeniable.
"All the patients could walk using body weight support within one week," says Blotch. In tests, the patients needed help to get around, but they had enough control of their limbs to even modify stride length and speed. They were actually capable of walking on a treadmill for an hour, or about a kilometer. The best part was the EES was only letting them walk, not stimulating their bodies to move involuntarily.
"The participants are constantly challenged to voluntarily generate the appropriate leg movements," says co-author Karen Minassian. "They need to be mentally active all the time in order to close the loop with the electrical stimulation that ultimately produces the muscle activity."
Because their brains were focused so hard on the task, it had the effect of restoring the severed nervous system connections over time. One patient, David Mzee, whose left leg had been paralyzed in a gymnastics accident in 2010, made stellar progress. Despite earlier physiotherapy doing nothing for him, after the EES implant, he was able to walk completely unassisted in just five months. Now, instead of a wheelchair, he can use a walker to get around on his own, thanks to the ESS. Another patient who lost use of both his legs, can walk short distances, but he's able to stand on his own.
The researchers say the degree of success for the treatment will depend on a number of things, including how severe the injury. After their study with just three patients, the scientists say the next step is understand better how the treatment might work for a larger population on average.
They also stress how important it is for the treatment to continue outside the hospital. They've developed a voice-activated system so the patients can turn the EES device on and off themselves. They've also calibrated it to different modes like walking, standing, and cycling.