Brain Stimulation and Robotics-Assisted Motor Training: New Frontiers in Physical Therapy?

Dylan J. Edwards, PhD, Director, Non-Invasive Brain Stimulation and Human Motor Control Laboratory at Burke Medical Research Institute and an assistant professor of neurology and neuroscience at Weill Cornell Medical College is using brain stimulation and robotics assisted motor training to help stroke patients and others with brain and spinal cord injuries. Ahead he discussed his research and explains where it may lead.

WHAT DOES THE TERM “BRAIN STIMULATION” REFER TO?

Dr. Edwards: In our case we’re using noninvasive brain stimulation, so that’s either electrical, where we put electrodes on the scalp and we pass a weak current across the scalp and some of that reaches the brain, or magnetic, where we use a coil that we hold adjacent to the scalp and that induces current in the brain.

We can use very, very low levels of this, which doesn’t actually activate neurons, but it can upregulate or down regulate the possibilities that they will fire. Or we can actually give sufficient intensity, where we make the neurons fire and we cause specific activity in the brain. Depending on which part of the brain we’re stimulating influences what functional outcome that has.

It’s noninvasive; there’s no surgery involved. We’ve been doing this for a number of years now. I have about 20 years of experience myself, and the the research practice has been running for about six or seven years. It has a great safety profile and it’s used to either to assay the nervous system to give us more information than just clinical examination alone or to actually positively influence the nervous system to improve recovery.

YOU ARE USING ROBOTIC ASSISTED MOTOR TRAINING AND STIMULATION. WHAT IS THIS AND HOW IS IT DIFFERENT?

Dr. Edwards: The concept of robotics is a bit nebulous and worth clarifying. In one sense it’s very sophisticated, because they’re electromechanical machines that have advanced computer algorithms that control them in a unique way, such that they’re not like industrial robots; they interact with humans in a safe and meaningful manner. But in the other sense, the principles upon which they operate are very simple and they are based on things that we know for learning and therapy, which is goal-directed repetitive activity where the person’s motivated and where they’re getting feedback about their performance and where they’re getting progressive improvement.

The robotics in the sense that we use here for our research and in the clinic are electromechanical machines. They’re mainly for the upper extremity here, so, for hand and arm function improvement. They interact with the person like an advanced gym machine. The person plays games on the robot for about an hour, and in that time they get activity that pushes the boundary of what their ability is, and the robot senses what they can do and can’t do and adjusts accordingly. It provides many repetitions, and they get feedback about their performance and they come back and they do that on multiple occasions.

“Robotic assisted” means the person needs to try to do it themselves; they’re not simply passively pushed around. They need to attempt to move and then the robot will assist with that movement, because usually it’s into a movement direction that they’re having difficulty with. So the principles behind it really are based on well-understood aspects of physical therapies and motor skill learning.

COULD YOU PROVIDE AN OVERVIEW OF THE RESEARCH AND THE GENERAL EXPERIENCE WITH BRAIN STIMULATION? WHERE DOES IT SHOW THE MOST PROMISE RIGHT NOW?

Dr. Edwards: Where this laboratory is unique is we’re trying to combine the advantageous therapeutic effects of brain stimulation with the advantageous therapeutic effects of the repetitive robotic assisted training in patients who have got a residual motor deficit following a stroke or spinal cord injury. Really, anyone who has an upper motor neuron injury with some residual function can probably benefit from this therapy.

We’re trying to combine these two therapies, and so really what we’re doing here is we’re looking to see how they can best be combined because robotic therapy, as advanced as it is, it’s well understood that it provides a good benefit for a certain proportion of the patients. It has been sanctioned by the American Heart Association and the Department of Defense; they have a physician statement on the use of robotics for people who are recovering from stroke.

But nevertheless, people don’t often fully recover, even though they get a marked improvement.

This neuromodulated technique of brain stimulation has been around for at least a decade or so. There’s in the order of several thousand publications on PubMed. There are hundreds of clinical trials registered on clinicaltrials. gov. The brain stimulation by itself can give some improvement, but it’s transient.

We’re trying to go that extra yard and combine the two together to see whether we can get a more prolonged and greater magnitude response.

The research we’re doing here—and we’re funded by the NIH to do this—is to use the brain stimulation as a priming tool for the robotic assisted therapy. Initially, we’re funded at the moment to study primarily stroke patients, but we’re expanding to spinal cord injury.

We have found that we can do this safely, it’s well tolerated by the patient. We have found that the brain stimulation can, in fact, have an improvement in the neurophysiology, so the output from the brain to the muscles that are dysfunctional can improve. It’s transient. It has an immediate effect on voluntary performance, and that’s transient too.

A single exposure for 20 minutes to this transcranial direct current stimulation can lead to improvement in the physiological outflow, if you like, to the muscles, and that translates into an improvement in volitional ability around that time period. Now we’ve shown that that can be effectively combined with the robotic therapy we do and now we’re offering this over around three months of multiple sessions of this combination. Sessions are offered three times a week, where brain stimulation precedes the robotic therapy. We’ve done around 1,000 sessions or so now, and we haven’t unblinded ourselves to the study, it’s a fully controlled, double-blind study, so we haven’t done a thorough analysis of the results yet, but no one’s gotten worse and on average there’s been a marked improvement in ability. So, we’re pretty excited about the results.

Dylan Edwards, PhD, PT, is director of Non- Invasive Brain Stimulation and Robotics at Burke Medical Research Institute and an assistant professor of neurology and neuroscience at Burke’s academic affiliate, Weill Cornell Medical College in New York City. Dr. Edwards is project director of a multimillion dollar NIH-funded project to investigate brain stimulation, including transcranial magnetic stimulation (TMS) and Transcranial Direct Current Stimulation (tDCS), and robotics at Burke, in collaboration with MIT and Harvard researchers.