Above: A prototype of MyHand, a glove-like device that would help stroke survivors regain hand function.
When a person has a stroke—perhaps a blood clot gets lodged in the brain or a blood vessel near the brain bursts—that person might suddenly not be able to hear, talk, or see. He or she might have trouble walking or may suffer a speech impediment. In fact, one of the greatest challenges of treating patients affected by stroke is that it’s a heterogeneous condition, says Joel Stein, a physiatrist at Columbia University and Weill Cornell Medical College in New York City. “It can affect any area of the brain,” he says. “There are large and small strokes; there are strokes that bleed into the brain, or block blood vessels, so it’s reasonable to believe that the recovery and treatment may not be the same for all these types of strokes.”
In the U.S., more than 800,000 people a year have a stroke; in Europe, the figure is close to a million. The costs associated with therapy and loss of productivity for patients after stroke come close to nearly US$34 billion a year, which makes it imperative to find different ways to help patients recover.
Because there are so many different ways that a stroke can happen, there’s no one-size-fits all solution to help patients recover. Researchers and engineers are therefore working on several different fronts to develop technologies that could be of assistance, from wearable robotic devices to developing virtual reality modules to help patients relearn movement. At the same time, doctors are also interested in incorporating brain stimulation techniques to enhance other technologies that might help patients recover more quickly from impairment following stroke.
The Bot Can Help You Now
Post-stroke, approximately 80% of patients lose normal functioning in one limb and often rely on canes and braces to help with walking. Although some patients can recover their mobility during physical therapy, they may have residual abnormalities in gait that would preclude them from participating in activities that could cause them to trip or fall — ultimately affecting their quality of life.
Over the years, robotic groups and engineers are developing wearable devices that can help patients restore mobility in a limb after a stroke. Recently, there’s growing interest in exoskeletons designed to provide external strength and movement that patients lose after stroke. The newer skeletons are being developed as soft exosuits with no rigid elements that would constrain someone’s movement. The goal, ultimately, would be to develop soft suits that are unobstructive, to be essentially worn as clothing.
One of the latest developments of this kind comes from the Wyss Institute for Biologically Inspired Engineering in Boston, Massachusetts. Researchers at the Wyss Institute have developed a soft exosuit to help stroke patients walk (above). This suit was originally made to help military personnel carry heavy loads and walk long distances while exerting less effort. Later, the team, led by Conor Walsh (below right) and Kathleen O’Donnell, wanted to leverage the success from the military application and apply it towards a medical condition: stroke. “Stroke seemed like a good opportunity for this technology because the exosuit works by providing small amounts of assistance, but at critical time points in the gait cycle to help improve your walking,” O’Donnell explains.
The exosuit developed by Wyss researchers uses cables to coordinate the movement of walking. One end of the suit is worn at the waist, where motion in patients’ hips generates a force to initiate walking. The other end is wrapped around the affected leg at the calf muscle and the insole of the patient’s shoe. Forces generated in the motor at the hips pulls on the cables that terminate at the insole. When this cable retreats, it shortens the distance between the calf wrap and the insole, causing the ankle joint to move and the person using the exosuit to walk.
So far, the Harvard team has looked at the immediate effect of these exosuits on the impact of walking in post-stroke patients and there’s a relatively small learning curve for people to correct their gait once the suit is on: the researchers have seen dramatic changes as early as the very first day that someone is trying on the system. The suit is designed in a way that it can adapt to an individual’s unique gait, says O’Donnell, the program lead for the medical exosuits program. “It doesn’t require you to walk with any particular step length or cadence. It measures the way you’re walking and adapts the timing of the assistance it delivers based on how you already walk.”
Moving forward, O’Donnell and her colleagues are intrigued to see if there are any lasting impacts on gait rehabilitation once the suit is taken away. “Those studies would take longer to run, but that’s an exciting area to start exploring: what are the benefits of wearing something like this over the long term?” The team is now collaborating with ReWalk, a robotics company headquartered in Marlborough, Massachusetts, and is working towards commercializing their technology. At a projected cost of US$19,500 per suit, these technologies would be purchased by rehabilitation clinics, and used by patients during their physical therapy sessions, according to Larry Jasinski, chief executive officer of ReWalk. The suits are intended to be used in the first few days after a stroke. In the best scenario, these suits can fully retrain the patients. In the future, ReWalk is looking to develop an exosuit that individuals can take home.
Another robotic device to train stroke patients to walk has already received clearance from the U.S. Food and Drug Administration. Ekso Bionics — a robotics exoskeleton company headquartered in Richmond, California — has developed the Ekso GT™. Made of aluminum and titanium, the exoskeleton re-trains users to walk by using information from the skeleton’s gyroscope, trajectory sensors, and torque sensors to assess how much help someone needs. The Ekso GT continually monitors the motion of the legs with the sensors and the patient’s posture to help initiate a step when user’s weight is properly shifted to their feet. A “trainer” or spotter can also walk behind the user to help initiate steps. Of the fifty or so patients who participated in a trial in the U.S., those who walked with the exoskeleton in a rehabilitation facility reported more independence, compared to those who used traditional physiotherapy techniques. Now, the suit is used in approximately 170 rehabilitation centers worldwide, according to Adam Zoss, a staff scientist at Ekso Bionics. Patients are using it soon after stroke so that they are walking as quickly and safely as possible. Patients continue to use it if they have a longer period of recovery.
Researchers are also developing robotics to help stroke patients who suffer from upper limb mobility issues. Rehab Robotics, a robotics company headquartered in Hong Kong, has developed the “Hand of Hope” for patients recovering from stroke. The device captures electrical signals from motor neurons that signal muscles to contract and sends them to the hand brace, which ultimately allows the hand to move. This device is not meant to be used during daily activities, says Haris Begovic, a clinical advisor at Rehab Robotics. Rather, it’s a therapeutic device often paired with customized games to help retrain the hand in the clinic.
And similar to how engineers at the Wyss Institute are developing soft exosuits, research scientists at the University of Texas at Arlington Research Institute in Fort Worth are developing soft robotic gloves to use in rehabilitation clinics and at home. These soft devices are focused specifically on helping patients regain movement of the fingers and thumbs, and rely on soft actuator sections that are attached to the joints of the hand. Ultimately, the device controls how the hand bends, flexes, and extends to retrain patients to grasp, manipulate objects, or gesture. The researchers have tested the robotic glove on healthy patients to assess fit and safety. Although they have yet to conduct any efficacy studies in stroke patients who have lost functionality in their hand, the team is in the early stages of commercializing the product to create a package that will incorporate both their device and virtual reality programs that will assist in retraining the hand. In the future, the hope is that the hand can re-wire the brain to compensate or adapt to the injury. For patients who can’t fully recover after prolonged use with the hand, the device can be used at home.
Stein and Matei Ciocarlie, a mechanical engineer at Columbia University, have created MyHand, a glove-like device that helps stroke survivors regain hand motion (pictured at the top of this article). MyHand, which uses artificial tendons to help stroke patients regain their ability to grasp objects, is still in development.
A New Reality
Therapists are also looking to virtual reality to help patients recover from stroke. Ordinarily, virtual reality (VR) immerses its users in an artificial, computer-generated environment where the user can interact with elements through devices like helmets or gloves fitted with sensors. Now, therapists are looking to use elements of VR to help patients recover from stroke.
It wasn’t until the mid-2000s that some VR technologies started making their way into clinics, according to Mindy Levin, a motor rehabilitation researcher at McGill University in in Montreal, Canada. “After stroke, patients move less; they’re not as active as they used to be,” Levin says. “And we know that activity is very important for enhancing brain function.” This means that any way to get a patient moving would be helpful in their rehabilitation. And over the years as the VR technology has advanced, some VR games can help address cognitive problems that patients experience post-stroke. Additionally, these technologies can help people regain mobility in their arms, legs, and hands.
Motekforce Link, a company that specializes in rehabilitation technologies headquartered in Amsterdam, has developed modules that incorporates VR onto a treadmill so that patients can walk or train in an immersive environment. Jintronix, a biomedical device company headquartered in Montreal, is incorporating upper limb training, balance, and gait, to be a part of their modules. Eodyne, a rehabilitation group based in Barcelona, Spain, developed a Rehabilitation Gaming System to help patients regain limb function, including in the hands.
These systems work by adding a game and reward-based element into the recovery process. The VR systems designed specifically for stroke recovery incorporate feedback to help patients regain motion. Some of these systems have been used in rehabilitation clinics in Europe and North America. For instance, in a module to help stroke patients with their gait, VR can bring the patient into an environment where he or she needs to walk across a busy intersection. A timer indicates to the user how long he or she has to walk across the street before the light changes. In a different module, a patient then follows footsteps as dictated on the screen to get better gait symmetry or cadence. The VR module could also have the user step on a rock, which would test the user’s balance. After a segment of the game is over, the user gets feedback in terms of how well they’re doing.
Researchers who are studying the effects of virtual reality on stroke rehabilitation are seeing how patients can benefit from these applications. And the field is evolving as motion tracking systems get better. Currently, high-end motion tracking can be expensive – up to hundreds of thousands of dollars. (Cheaper ones lack the same accuracy of tracking.) According to Levin, researchers are now looking for motion trackers that are based on accelerometry, or visual tracking, to be able to better sense the movement of patients.
Brain Stimulation Techniques
While robotics and virtual reality can lead to some modest gains in rehabilitation post-stroke, researchers are looking at ways to stimulate the brain using electrical or magnetic means to augment the gains from physical therapy. These techniques are still experimental and clinicians are still validating their use in stroke patients.
Transcranial Direct Stimulation (tDCS) is a noninvasive approach where physicians apply direct electrical current to stimulate specific areas of the brain. This current passes through two electrodes placed over the head, which can then modulate neuronal activity. A stroke patient, for instance, could be wearing a cap that would be hooked onto the tDCS electrodes and receive the stimulation before he or she goes into a physical therapy session. It’s thought that this prior brain stimulation could potentiate the effects of exercise. “This method is appealing since it’s easy, very safe, and readily combined with other treatments,” Smith says. However, despite its potential, tDCS is not yet an FDA-approved treatment.
n a second method, called transcranial magnetic stimulation (TMS), neurologists would use a small electromagnetic coil to deliver bursts of magnetic energy to certain parts of the patient’s brain after stroke. This magnetic field would then induce an electrical current that modulates the electrical currents in the patient’s brain. Compared to tDCS, it would be impractical to deliver TMS during other treatments, but it could be used prior to therapy and may increase gains experienced beyond just exercise therapy alone. Evidence suggests that TMS, especially if done repetitively, could affect motor behavior in stroke patients.
In spite of these new technological advancements in robotics, virtual reality consoles, and the added research in brain stimulation techniques, stroke patients have yet to make substantial gains in recovery, says Smith. “One hypothesis why it could be so difficult to get those gains is because we haven’t found the right treatments — or combination of treatments. The other may be that the brain’s ability to recover has a biological limit,” he explains. Researchers are also starting to investigate the pairing of stem cells and growth factors to help the brain repair itself more effectively post-stroke, but many of these techniques are still in their infancy and have yet to be brought into clinical trials.
Fully rehabilitating patients who are left with physical disabilities after a stroke is likely to remain a challenge in the short term, but recent advances in technology and research suggest that in the long term, stroke survivors will one day have a range of methods available to recover and rehabilitate faster and more fully.
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