Restoring Ability: Project NEUWalk

neuwalkIn the past few years, medical science has produced some pretty impressive breakthroughs for those suffering from partial paralysis, but comparatively little for those who are fully paralyzed. However, in recent years, nerve-stimulation that bypasses damaged or severed nerves has been proposed as a potential solution. This is the concept behind the NEUWalk, a project pioneered by the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland.

Here, researchers have figured out a way to reactivate the severed spinal cords of fully paralyzed rats, allowing them to walk again via remote control. And, the researchers say, their system is just about ready for human trials. The project operates on the notion that the human body requires electricity to function. The brain moves the body by sending electrical signals down the spinal cord and into the nervous system.

spinal-cord 2When the spinal cord is severed, the signals can no longer reach that part of the spine, paralysing that part of the body. The higher the cut, the greater the paralysis. But an electrical signal sent directly through the spinal cord below a cut via electrodes can take the place of the brain signal, as the team at EPFL, led by neuroscientist Grégoire Courtine, has discovered.

Previous studies have had some success in using epidural electrical stimulation (EES) to improve motor control where spinal cord injuries are concerned. However, electrically stimulating neurons to allow for natural walking is no easy task, and it requires extremely quick and precise stimulation. And until recently, the process of controlling the pulse width, amplitude and frequency in EES treatment was done manually.

brainwavesThis simply isn’t practical, and for two reasons: For starters, it is very difficult for a person to manually adjust the level of electrostimulation they require to move their legs as they are trying to walk. Second, the brain does not send electrical signals in an indiscriminate stream to the nerves. Rather, the frequency of the electrical stimulation varies based on the desired movement and neurological command.

To get around this, the team carefully studied all aspects of how electrical stimulation affects a rat’s leg movements – such as its gait – and was therefore able to figure out how to stimulate the rat’s spine for a smooth, even movement, and even take into account obstacles such as stairs. To do this, the researchers put paralyzed rats onto a treadmill and supported them with a robotic harness.

NEUWalk_ratsAfter several weeks of testing, the researchers had mapped out how to stimulate the rats’ nervous systems precisely enough to get them to put one paw in front of the other. They then developed a robust algorithm that could monitor a host of factors like muscle action and ground reaction force in real-time. By feeding this information into the algorithm, EES impulses could be precisely controlled, extremely quickly.

The next step involved severing the spinal cords of several rats in the middle-back, completely paralyzing the rats’ lower limbs, and implanted flexible electrodes into the spinal cord at the point where the spine was severed to allow them to send electrical signals down to the severed portion of the spine. Combined with the precise stimulation governed by their algorithm, the researcher team created a closed-loop system that can make paralyzed subjects mobile.

walkingrat.gifAs Grégoire Courtine said of the experiment:

We have complete control of the rat’s hind legs. The rat has no voluntary control of its limbs, but the severed spinal cord can be reactivated and stimulated to perform natural walking. We can control in real-time how the rat moves forward and how high it lifts its legs.

Clinical trials on humans may start as early as June 2015. The team plans to start testing on patients with incomplete spinal cord injuries using a research laboratory called the Gait Platform, housed in the EPFL. It consists of a custom treadmill and overground support system, as well as 14 infrared cameras that read reflective markers on the patient’s body and two video cameras for recording the patient’s movement.

WorldCup_610x343Silvestro Micera, a neuroengineer and co-author of the study, expressed hope that this study will help lead the way towards a day when paralysis is no longer permanent. As he put it:

Simple scientific discoveries about how the nervous system works can be exploited to develop more effective neuroprosthetic technologies. We believe that this technology could one day significantly improve the quality of life of people confronted with neurological disorders.

Without a doubt, restoring ambulatory ability to people who have lost limbs or suffered from spinal cord injuries is one of the many amazing possibilities being offered by cutting-edge medical research. Combined with bionic prosthetics, gene therapies, stem cell research and life-extension therapies, we could be looking at an age where no injury is permanent, and life expectancy is far greater.

And in the meantime, be sure to watch this video from the EPFL showing the NEUWalk technology in action:


Sources:
cnet.com, motherboard.com
, actu.epfl.ch

Biomedical Breakthroughs: Bionerves and Restored Sensation

restoring_mobilityThese days, advances in prosthetic devices, bionic limbs and exoskeletons continue to advance and amaze. Not only are doctors and medical researchers able to restore mobility and sensation to patients suffering from missing limbs, they are now crossing a threshold where they are able to restore these abilities and faculties to patients suffering from partial or total paralysis.

This should come as no surprise, seeing as how the latest biomedical advances – which involve controlling robotic limbs with brain-computer interfacing – offer a very obvious solution for paralyzed individuals. In their case, no robotic limbs or bionic attachments are necessary to restore ambulatory motion since these were not lost. Instead, what is needed is to restore motor control to compensate for the severed nerves.

braingate1Thanks to researchers working at Case Western University in Ohio, a way forward is being proposed. Here, a biomedical team is gearing up to combine the Braingate cortical chip, developed at Brown University, with their own Functional Electric Stimulation (FES) platform. Through this combination, they hope to remove robots from the equation entirely and go right to the source.

It has long been known that electrical stimulation can directly control muscles, but attempts to do this in the past artificially has often been inaccurate (and therefore painful and potentially damaging) to the patient. Stimulating the nerves directly using precisely positioned arrays is a much better approach, something that another team at Case Western recently demonstrated thought their “nerve cuff electrode”.

cuff-electrodeThis electrode is a direct stimulation device that is small enough to be placed around small segments of nerve. The Western team used the cuff to provide an interface for sending data from sensors in the hand back to the brain using sensory nerves in the arm. With FES, the same kind of cuff electrode can also be used to stimulate nerves going the other direction, in other words, to the muscles.

The difficulty in such a scheme, is that even if the motor nerves can be physically separated from the sensory nerves and traced to specific muscles, the exact stimulation sequences needed to make a proper movement are hard to find. To achieve this, another group at Case Western has developed a detailed simulation of how different muscles work together to control the arm and hand.

braingate2-img_assist_custom-500x288Their model consists of 138 muscle elements distributed over 29 muscles, which act on 11 joints. The operational procedure is for the patient to watch the image of the virtual arm while they naturally generate neural commands that the BrainGate chip picks up to move the arm. In practice, this means trying to make the virtual arm touch a red spot to make it turn green.

Currently in clinical trials, the Braingate2 chip is being developed with the hope of not only stimulating muscles, but generating the same kinds of feedback and interaction that real muscle movement creates. The eventual plan is that the patient and the control algorithm will learn together in tandem so that a training screen will not be needed at all and a patient will be able to move on their own without calibrating the device.

bionic-handBut at the same time, biotech enhancements that are restoring sensation to amputee victims are also improving apace. Consider the bionic hand developed by Silvestro Micerna of the École Polytechnique Fédérale de Lausanne in Switzerland. Unlike previous bionic hands, which rely on electrodes to receive nerve signals to control the hand’s movement, his device sends electronic signals back to simulate the feeling of touch.

Back in February of 2013, Micerna and his research team began testing their bionic hand, and began clinical trials on a volunteer just last month. Their volunteer, a man named Dennis Aabo Sørensen from Denmark, lost his arm in a car accident nine years ago, and has since become the first amputee to experience artificially-induced sensation in real-time.

prosthetic_originalIn a laboratory setting wearing a blindfold and earplugs, Sørensen was able to detect how strongly he was grasping, as well as the shape and consistency of different objects he picked up with his prosthetic. Afterwards, Sørensen described the experience to reporters, saying:

The sensory feedback was incredible. I could feel things that I hadn’t been able to feel in over nine years. When I held an object, I could feel if it was soft or hard, round or square.

The next step will involve miniaturizing the sensory feedback electronics for a portable prosthetic, as well as fine-tuning the sensory technology for better touch resolution and increased awareness about the movement of fingers. They will also need to assess how long the electrodes can remain implanted and functional in the patient’s nervous system, though Micerna’s team is confident that they would last for many years.

bionic-hand-trialMicerna and his team were also quick to point out that Sørensen’s psychological strength was a major asset in the clinical trial. Not only has he been forced to adapt to the loss of his arm nine years ago, he was also extremely willing to face the challenge of having experienced touch again, but for only a short period of time. But as he himself put it:

I was more than happy to volunteer for the clinical trial, not only for myself, but to help other amputees as well… There are two ways you can view this. You can sit in the corner and feel sorry for yourself. Or, you can get up and feel grateful for what you have.

The study was published in the February 5, 2014 edition of Science Translational Medicine, and represents a collaboration called Lifehand 2 between several European universities and hospitals. And although a commercially-available sensory-enhanced prosthetic may still be years away, the study provides the first step towards a fully-realizable bionic hand.

braingate_drinkassistYes, between implantable electronics that can read out brainwaves and nerve impulses, computers programs that are capable of making sense of it all, and robotic limbs that are integrated to these machines and our bodies, the future is looking very interesting indeed. In addition to restoring ambulatory motion and sensation, we could be looking at an age where there is no such thing as “permanent injury”.

And in the meantime, be sure to check out this video of Sørensen’s clinical trial with the EPFL’s bionic hand:


Sources:
extremetech.com, actu.epfl.ch, neurotechnology.com