Can Stimulation Improve Walking and Dexterity for People Living with MS?

An Interview with Dr. Roger Enoka with the Neurophysiology of Movement Laboratory at University of Colorado Boulder campus

Dr. Roger Enoka, a professor at the University of Colorado Boulder, has been working closely with physicians from the Rocky Mountain MS Center at University of Colorado in developing studies testing neuromuscular electrical stimulation in patients with MS. The new study is now accepting participants in or near the Boulder campus. We recently talked to Dr. Enoka for some more information. 

RMMSC: Dr. Enoka, could you please tell us a little about your background and your role at CU Boulder?

Dr. Roger Enoka: I’m a professor in the Department of Integrative Physiology. I’ve been interested in fatigue for several decades, and for the last few years I’ve been developing a collaborative project with Dr. Timothy Vollmer, Dr. John Corboy, and Dr. Enrique Alvarez at Rocky Mountain MS Center at the Anschutz Medical Campus. I’ve been at CU Boulder since 1996 studying neuromuscular physiology in healthy adults and in various clinical populations.

RMMSC: Could you please describe your research efforts on nerve stimulation and MS?

Dr. Enoka: A few years ago, we started thinking about using electrical nerve stimulation as a way to supplement muscle activation in people with MS. Our first clinical trial took three years and involved 27 people with MS. The participants took part in a 6-week intervention in which they came into the lab 18 times and were treated with a type of stimulation called Neuromuscular Electrical Stimulation (NMES). This type of treatment applies electrical current that evokes muscle contractions, so it’s reasonably strong. And the amount of current depended on whatever the person is willing to tolerate.

RMMSC: What does the NMES treatment involve?

Dr. Enoka: Participants would sit or stand in a position and then their leg muscles were stimulated for approximately twenty minutes, three times a week for six weeks. Then we measured the effects on mobility and other outcomes, including the patient perception of fatigue and walking ability.

RMMSC: What were the results of that study?

Dr. Enoka: In practically everything we measured, there was a clinically significant improvement in function for these individuals. The distance that they could walk in 6 minutes increased; their average walking speed increased; and their ability to get out of a chair rapidly improved. Participants also perceived fatigue to be less of a problem during daily routines. In a nutshell, the outcomes for participants were very positive. The one negative aspect of the study, however, is that the device we used was expensive and is actually only available in clinics.

RMMSC: Given those positive results, what are your plans for next steps to try to overcome the cost and current lack of broad access for the treatment?

Dr. Enoka: Dr. Vollmer encouraged us to think about an alternative application that patients could manage on their own. Thus, we began to explore transcutaneous electrical stimulation (TENS). These devices are portable and cost approximately $120, and a patient can be taught how to use them at home. The amount of electricity is much less with TENS than it is with NMES and the person just feels a tingling sensation.

We did one initial pilot study on TENS involving 15 patients and we had them do these standard clinical tests measuring mobility and other functional characteristics. Then we put the TENS device on to apply the stimulation to leg muscles and we had them repeat the same tests. And again, when we put the device on and applied the current, they walked further in 6 minutes, they walked faster over 25 feet, and they felt more confident. While the current was being applied, their mobility improved substantially.

It’s very encouraging, but now we need to know: If we do several treatment sessions and then have the person repeat these tests without stimulation, is their mobility improved? And that is the point of this next preliminary study. We need to be able to demonstrate that it is an effective therapy, and if the reviewers approve that, we will begin a larger clinical trial to test it more carefully.

RMMSC: What will this new study involve for people who are interested in participating?

Dr. Enoka: The study will involve 2 evaluation visits (before and after treatment) and 9 treatment sessions taking place 3 times per week for 3 weeks. TENS will be applied to sensory fibers in arm and leg muscles during each 40-minute treatment session. The unique feature of this study is that we are targeting sensory nerves rather than those that produce muscle contractions (motor nerves). Evaluation sessions will involve answering questionnaires and performing tests of mobility and muscle function.

RMMSC: After the study has been completed, how will the results be shared?

Dr. Enoka: Our intent is to publish the results in a scientific journal that specializes in reporting the results of studies on persons with multiple sclerosis. We will enroll up to 20 individuals so that the results reflect the potential outcomes for a range of disability levels. In addition, each participant will receive their own individual results as well as the group results. Also, we will make ourselves available to speak with patient groups about the findings and explain what we think the outcomes mean.