From the department of very good news |Kate Willette

Posted by Reeve Staff in Research News on July 05, 2018 # Research, Technology

During the first year or so after my husband broke his neck, there was a period of several months where spasticity in his trunk and legs just about drove us both crazy, especially at night. Eventually his nurses found a combination of pills that got it under control, or maybe his nervous system just settled down to a different reality; it’s impossible to know. What I remember from that time is my own irrational and silly recoil at the idea of a baclofen pump. I just didn’t want “them” to do anything else to him. I didn’t want him to have to go back into the hospital. I didn’t want to think about some piece of equipment lodged inside his body, forever.

It was dumb, of course. Those pumps make a whole lot of people’s lives better, and if it had come to that, I’m sure I would have seen the sense of it. What I was reacting to wasn’t completely crazy, though. It really is better to have an option for less invasive therapies – for interventions that work but don’t require surgery.

That’s why I’m so glad to report on two newly published papers, both of which have to do with neural network stimulation that doesn’t involve surgery. One is from the lab of one of the Reeve Foundation’s International Research Consortium members, Dr. Chet Moritz. The other is from the lab of Dr. Reggie Edgerton, an emeritus member of that same group. Both papers reflect work that has been ongoing for the last few years, both use the exact same technology, and both are well worth the time and effort to read carefully. Dr. Moritz discussed this study at the 2017 Working 2 Walk conference in Miami; the video of his presentation is here.

To review, neural network stimulation has until now meant surgically opening the back and implanting electrodes into the epidural space, which is why it’s known as epidural stimulation. It’s not a complicated procedure; it takes less than an hour and is routinely done without hospital admission.

Recently I told you about Dr. Yury Gerasimenko’s 2016 paper, which demonstrated for the first time that epidural stimulators placed in the cervical area of two men with motor-complete, chronic cervical injuries produced muscle movement in their hands and fingers. Until that paper, we only knew that placing epidural stimulators in the lumbar area could produce movement in the feet and legs.

It was only two patients, but Dr. Gerasimenko and his team had shown that there was plenty of reason to investigate further, which is exactly what’s happened. The good news is that the stimulators in the new studies weren’t implanted.

There was no surgery.

The electrodes were placed directly on the skin at the back of the neck, and the results were the same: the subjects recovered movement and increased strength. What’s more, that recovery was almost immediate. From Dr. Edgerton’s paper:

Improved voluntary hand function occurred within a single session in every subject tested.

There were eight subjects in Dr. Edgerton’s original study, but by the end two of them had to leave for reasons not related to the research study itself. All of them had injuries above C7, all of them were at least one year post-injury, and none of them were vent-dependent. They were classified as AIS B and AIS C, meaning that going in, their hand strength and mobility landed somewhere from non-existent to weak.

As usual, the study began with establishing baseline function: what exactly could each participant do before the intervention? Once that data was recorded, they came to the lab twice a week for four weeks. Each session lasted between one and two hours, and each time the process was the same. A pair of stimulating electrodes was placed at the back of their necks. The participants did their tasks – operating a hand-grip machine, for example – without any assistance from the stimulator.

 Photo credit Matt Hagen, University of Washington

Then the stimulator was turned on; the subjects themselves would tell the researchers when it felt like the current was right. I spoke to the man who was in Dr. Moritz’s study recently, and he told me that the stimulator makes your skin tingle a little bit at the place where the electrodes are attached, and that you can feel it travel right up and down the center of your spinal cord. Dr. Edgerton’s group has christened this intervention tEmc , which stands for transcutaneous enabling motor control– a name that’s meant to emphasize that the stimulator enables (but does not directly cause) movement. It’s nothing like what happens on an FES bike, where the electrodes send current right to your the muscles and cause them to contract while you think about the weather or what’s for dinner. With tEMC , your intent and effort to move are necessary.

With the current flowing, participants would go through exercises designed to measure hand strength and mobility. The result?

Recovery of increased hand grip function within one session and a mean increase of approximately 325% (with tEmc) from baseline measurements after 8 treatment sessions over 4 weeks … levels of connectivity of descending-ascending networks between the brain and spinal cord that initially were not detectable in the absence of tEmc can be transformed … to a significantly greater level of function, including strength and control of grip forces.

What this means is that these scientists have found an intervention that doesn’t involve drugs or surgery or insanely expensive technology. The person I was back when my husband was newly injured would be thrilled. We’re at a turning point. It’s important to remember, though, that turning points are by definition full of unknowns. The list of questions still to be answered includes how to combine this treatment with any of half a dozen others now being studied. We’re far from knowing the best or most efficient ways to combine tEMC with training. We don’t know if there are situations where an implanted stimulator would be better, or how it would work to use more than one set of tEMC electrodes on a subject. The possibilities are frankly staggering, as are the challenges to finding the most efficient way forward.

But it will happen.

Stay tuned.

(Photo credit Matt Hagen, University of Washington)