Smart walk assist improves rehabilitation

AI can help patients recover ability to stand and walk.

When training to regain movement after stroke or spinal cord injury (SCI), patients must once again learn how to keep their balance during walking movements. Current clinical methods mean supporting the weight of the patient during movement, setting the body off balance. Until patients are ready to walk without mechanical assistance, it can be hard to re-train the body to balance against gravity. It is this issue a team is attempting to solve, led by Courtine-Lab, and featuring Ijspeert Lab, NCCR Robotics and EPFL. Jean-Baptiste Mignardot photo. New Scientist

By Charles Q. Choi, IEEE Spectrum 19 July 2017

Artificial intelligence software combined with a robotic harness could help spinal injury and stroke patients walk again. Clinical trials are underway.

Rehabilitation programs for spinal cord injuries or strokes usually have patients walk on treadmills at a steady pace while harnesses support their weight to varying degrees. In the new study, researchers sought to develop a system that better mimicked the conditions that people might experience during everyday life, where they would have to move in more than one direction and vary their gaits.

“The idea is to provide the most appropriate environment for patients to be active during training,” says study co-author Grégoire Courtine, a neuroscientist at the École polytechnique fédérale de Lausanne EPFL. “The goal of this rehabilitation is to have patients repeat natural activities for an extended amount of time.”

The scientists developed a robotic harness that uses cables to control the amount of upward and forward force that patients feel while also permitting them to walk forwards, backwards, and side to side. This robotic harness was controlled by software that personalized the multidirectional forces that each patient experienced depending on their specific problems.

In order to customize patient experiences, this system relied on an artificial neural network, where components known as artificial neurons are supplied data and work together to solve a problem. The neural net can then alter the pattern of links among those neurons to change the way they interact, and the network tries solving the problem again. Over time, the neural net learns which patterns are best at computing solutions, an AI strategy that imitates the human brain.

The neural net the researchers used analyzed roughly 120 different variables of patient movements, such as how fast they could walk, and then computed what kind of support they should need. “The amount of support that patients receive is calculated precisely for each patient,” Courtine says. “If patients need only as much gravity as they would experience walking on the moon, the harness creates a moon-like feeling of gravity, and if the patients are stronger, it creates, say, a Mars-like feeling of gravity.”

As part of a clinical trial of this “neurorobotic platform,” the researchers experimented with 26 volunteers recovering from spinal cord injuries or strokes, whose disability ranged from being able to walk without assistance to being able to neither stand nor walk independently.

The participants were tested on four tasks—standing on two separate plates, walking on a straight path, walking on a wavy path, or walking on a ladder with irregularly positioned rungs. They either had or did not have robotic assistance in such tasks.

After the volunteers walked roughly 20 meters using the neurorobotic platform to familiarize themselves with the apparatus, three patients with spinal cord injuries who previously could not stand independently could, immediately after such practice, walk with or without assistance. Four of 10 patients with spinal cord injuries who previously could only move with crutches or a walker could, immediately after such practice, do so without assistance. Similar or even superior findings were seen with stroke patients, the researchers say.

Furthermore, after a one-hour training session with the neurorobotic platform, four out of five patients with chronic spinal cord injuries who previously could only walk with the assistance of a device experienced significant improvements, such as increase in speed, the researchers say. In contrast, the same amount of time on just a treadmill actually impaired the ability to walk without robotic assistance in one patient.

“It’s striking how a system that applies force in directions other than just vertical can make a world of difference,” Courtine says.

The scientists are also exploring how spinal cord stimulation can improve patient mobility. They are combining that approach with their neurorobotic platform, Courtine says.

The neurorobotics platform will be commercialized under the name Rysen by Amsterdam-based Motekforce Link and by G-Therapeutics, which is headquartered in Eindhoven in the Netherlands as well as Lausanne, Switzerland. The researchers detailed their findings online July 19 in the journal Science Translational Medicine.

Source IEEE Spectrum
Via Science Daily

Delicate balance
“The algorithm evaluates the optimal amount of body weight support for each patient,” says Grégoire Courtine, one of the study authors at EPFL’s Brain Mind Institute. This helps them rebuild lost muscle mass and relearn posture and movement, while also retraining their brains to handle the delicate balance between gravity and forward motion that walking requires.

The new system improved the in-harness gait of people following a stroke or a spinal injury. And after a single, 1-hour training session with the smart harness, people with spinal cord injury showed immediate improvement in their gait out of the harness over those given no physio session at all, the authors report today.

Artificial intelligence is widely used in rehabilitation, says Farshid Amirabdollahian at the University of Hertfordshire, UK. “We have multiple products in the market where robots help individuals recover from stroke,” he says. These include robotic gloves that exercise the hand and wrist, and a rehabilitation robot that encourages and aids repetitive exercises at home.

For walking assistance, even robotic harnesses that operate without algorithms have become smarter at load balancing and understanding how far to push people, using readings on muscle activity and brain scans, says Amirabdollahian. “As the systems become more clever, the results of the rehabilitation become much better,” he says.

The next goal is to commercialise the smart harness, dubbed RYSEN, alongside further clinical trials, says Courtine.

Read Robot physical therapist helps people walk again after a stroke by Nicole Kobie in New Scientist

A multidirectional gravity-assist algorithm that enhances locomotor control in patients with stroke or spinal cord injury, Mignardot J-B, Le Goff CG, van den Brand R, Capogrosso M, Fumeaux N, Vallery H, Anil S, Lanini J, Fodor I, Eberle G, Ijspeert A, Schurch B, Curt A, Carda S, Bloch J, von Zitzewitz J, and Courtin, G. Science Translational Medicine 19 Jul 2017: Vol. 9, Issue 399, eaah3621 DOI: 10.1126/scitranslmed.aah3621

Smart walk assist improves rehabilitation, École polytechnique fédérale de Lausanne EPFL. Published on YouTube July 19, 2017

Also see
Multi-directional gravity assist helps rehabilitation training in EPFL
Smart harness can help stroke victims learn to walk again in Engadget
Wearable sleeve could improve stroke recovery therapy in Engadget

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