Complete spinal cord paralysis is thought to be irreversible, but new research suggests brain-controlled robotics with tactile feedback may reactivate circuitry between the brain and nerves, effectively restoring some lower-body movement and sensation.
In a study published Thursday in the journal Scientific Report, the method resulted in seven participants improving from complete paraplegia to incomplete paraplegia. About halfway through training, spinal cords that were once damaged and dormant improved.
“I was shocked,” lead study author Dr. Miguel Nicolelis, director of the center for neuroengineering at Duke University, told FoxNews.com. “I would never expect in six, seven months we could see signs of recovery of any sort. Some of these patients had [spinal] lesions for more than a decade.”
Seven of eight participants— six men and two women— completed three stages of training over 12 months as part of a study by the Walk Again Project in Sao Paolo, Brazil, a collaboration of more than 100 scientists from 25 countries.
During most of the training, patients wore a sleeve equipped with sensors that gave tactile feedback, similar to the buzzing jolts felt by a gamer using a handheld controller. The patient’s brain generates a realistic sensation that his or her leg is working, and participants reported feeling like they were moving again.
Patients began by working in virtual reality, where they learned how to operate their own avatar. They were fitted with caps lined with non-invasive electrodes that recorded their brain activity through electroencephalogram (EEG) and were asked to imagine walking in their virtual environment. Scientists did not observe the expected signals in areas associated with motor control of the legs. But six to eight weeks into the training, they witnessed brain activity when patients thought about moving their legs.
“Interesting enough, at that point, they started reporting that they had a very different experience— [they were] feeling the tactile feedback, even in virtual reality, telling them, ‘I know I’m upright and standing, but it feels like my legs are moving,’” said Nicolelis, also a neurobiology professor at Duke.
When patients felt the phantom sensation, they were moved to the ZeroG, a standing robot that supports the user overhead so he or she is essentially weightless. Then they were advanced to the Lokomat, a robotic exoskeleton on a treadmill that produces a more realistic walking experience.
Patients not only regained motor and sensory skills, but their bladder control, bowel function and movement also improved. Paraplegics are at high risk of urinary infections, which can lead to fatal complications.
“Now they can get out of their house, don’t need to wear diapers, can drive adapted cars,” Nicolelis said. “Some patients even got a job for the first time.”
Patients’ ages ranged from 26 to 38, and their injuries were as recent as three years to as old as 13 years.
“The consensus was that you could not improve,” Nicolelis said. “This may change the philosophy toward patients with so-called clinically complete lesions.”
In their ongoing, post-study training, participants are not walking autonomously but rather in the robotic devices. Some patients can move the exoskeleton legs independently, meaning they are able to maintain or increase their muscle mass.
“We hope this is something they can do for life, in terms of improving quality of the muscles, bones and joints, because these all decay because of the [spinal] lesions,” Nicolelis said.
The effect of tactile feedback
At the end of the study period, in December 2014, half of the patients were reclassified from complete paraplegia to partial paraplegia. In June, all remaining patients were reclassified. Because the last patient changed categories in May, researchers pointed out that clinicians doing similar work in the future should work as long as they can with patients.
“All lesions are different, so the timing for everyone is different,” Nicolelis said.
Before the study ended, one patient moved and dropped out. The abilities he gained during training have since declined, Nicolelis said.
Virtual reality has been studied for paralysis, but only with the visual element, not the haptic feedback of feeling the ground, the leg flexing or extending, and touching the heel— which is the key to their success, as it reinforces the internal concept of walking learned during childhood, researchers said.
“That was a very important component for this recovery because the brain is basically working now like it used to in the past when the patient was able to walk,” Nicolelis said. “The combination of the brain connection, plus feedback, plus the walking, all these three factors may contribute to [progress].”
With a spinal lesion, it’s as though the brain starts forgetting this information, which is why, to reinsert the concept of walking, the body needs a very realistic environment that involves these sensations, he added. Patients weren’t allowed to use personal technology like cellphones so they could maintain focus during therapy, and the concentration made them feel like they were really working out again, they reported.
Walking in the ZeroG and Lokomat stimulates the patients’ nerves, reactivating messaging between their brains and that of their muscles, ligaments and joints.
“This may be the difference that allowed us to observe this clinical recovery that nobody has seen with a more passive approach,” Nicolelis said. “It seems you need to engage the brain actively to trigger this kind of recovery.”
“We’re going to keep going”
Researchers’ previous work found that, in an individual can be completely paralyzed from a clinical standpoint, 2 to 10 percent of the nerves may survive the original spinal cord trauma. In the new study, they observed that training could trigger nerve recovery enough to carry messages from the brain to the spinal cord, and from the spinal cord to the brain, on only a few surviving fibers.
They aren’t sure how long progress may persist, or if or when it may plateau.
“Basically, we’re going to keep going as long as we can to see how far we can take [it],” Nicolelis said. Participants now undergo training twice a week for about an hour.
While the patients were young, researchers did not think age affected the success of the technology. More important, they believe, is that they find patients for their next study group who suffered spinal cord injuries more recently, rather than a decade out.
Next, researchers participating in the Walk Again Project want to disseminate their training protocol to make their findings accessible to other research institutions. They hope other scientists will replicate the results.
“It gives hope that when scientists from different countries, domains and disciplines get together to achieve a goal— and our goal was very humble, just to get patients moving— we never imagined we’d get to this,” Nicolelis said. “When you get this collaboration on an international level, you can really achieve very, very important things from a humanitarian point of view.”