Functional Electrical Stimulation for Multiple Sclerosis

Multiple sclerosis is a devastating neurological disease that attacks the central nervous system and strikes without warning or prejudice. According to the National Multiple Sclerosis Society, an estimated 400,000 Americans have multiple sclerosis (MS), with approximately 200 cases being diagnosed every week. Worldwide, MS is estimated to affect as many as 2.5 million individuals. As the disease progresses and affects the lower extremities, orthotic management can help patients retain mobility and function. One recent and exciting development for orthotists in the management of patients with MS is the use of functional electrical stimulation (FES).

Multiple sclerosis

Multiple sclerosis is a progressive disease involving the central nervous system. The disease most commonly starts between the ages of 20 and 50 and is uncommonly diagnosed as a new disease in the very young and the very old. A gender predisposition exists, with women being affected two to three times more frequently than men.

Image reprinted with permission of Innovative Neurotronics.

Although MS is not an inherited disease, there is evidence that genetic factors make some people more susceptible to the disease. Multiple sclerosis also occurs in whites almost twice as frequently as in non-whites.

In addition, a geographic distribution has been found, with few cases occurring at the equator and the incidence increasing as the distance from the equator increases in both the southern and northern hemispheres. In the United States, the incidence starts to increase in the southern states, with a maximum incidence occurring in the mid to northern states and up into southern Canada. This geographic distribution of cases and the nature of the disease suggest there may be something in the environment that triggers an autoimmune-type response. However, this theory has not been validated by research.

There are several different types of multiple sclerosis, ranging from relapsing and remitting MS to primary progressive MS, with the majority of patients having the relapsing and remitting type. However, symptoms vary considerably from patient to patient as well as over time in the same patient, making the disease unpredictable and difficult to diagnosis.

“There will be people who carry the diagnosis but are perfectly fine. There are others who are in wheelchairs and have no use of their legs, and it turns out that there are a fair number of patients in the group who have MS who will be in the state where they have some weakness of their legs, often including foot drop,” said Conrad Kufta, MD, director of clinical development for Innovative Neurotronics Inc.

Orthotic management

As the disease progresses and patients begin to experience lower extremity difficulty, orthotic management may be implemented to help patients remain mobile and also to help prevent future deformities such as a plantarflexion contracture. Traditionally, orthotic management of MS consists of a custom ankle-foot orthosis (AFO).

“Where we as orthotists get involved is to keep them safe when they are functioning, therefore when they are walking,” said Marleta Ouverson, BS, an orthotist and prosthetist for Hanger Prosthetics & Orthotics. “What we would typically do is mold them for a custom AFO.”

Because the majority of patients with MS are young adults in their most productive years, they want to remain physically active as possible. Although AFOs help patients walk safely, use of the orthoses can be restrictive and patients often resist wearing or choose not to wear the orthoses.

“Unfortunately, because braces, not so much the weight of them, but because they seem to add a negative feel to a person, meaning a person feels like they are not getting better if they have to wear a brace, that it is almost like a step back to them. So many times when we make braces for patients, we find often that it goes into the closet,” said Peter W. Vales, CPed, BOCO, CO, president of the Brace Doctor Inc.

Electrical stimulation

During the past several decades, the principles of FES have been applied to develop therapeutic devices for neurological conditions. While a number of devices have proved successful in the past, the bulk and size of the devices precluded their widespread use.

“The basic principles of FES, meaning the concept, have been around for a while,” Kufta said. “The problem has been that the technology was not there to make it patient friendly. In other words, you could build a huge box and have it walk alongside the patient and stimulate the nerve, but it just was not practical.”

However, advances in technology and microelectronics have converged to allow the development of portable orthotic devices that incorporate FES to address symptoms of neurological conditions and diseases such as multiple sclerosis, cerebral palsy, spinal cord injuries, traumatic brain injuries and stroke.

“The technology is at a size and a complexity that allows you to build something that is small enough to wear, unobtrusive and has ‘a brain in the box’ basically that would do more things than the old systems could do, and the patient does not have to learn a lot of stuff to use it,” Kufta said. “It is the convergence of many factors that makes what is an old idea and an old dream just really at the point now where you can start to employ this.”

Because MS is a central nervous system disease that does not involve the peripheral nervous system, patients with MS are good candidates for FES, which relies on an intact peripheral nervous system. Two orthotic devices incorporating FES that recently have become available commercially are the Lower Extremity NeuroProsthesis, manufactured by Bioflex Electromedicine Inc., and the WalkAide, manufactured by Innovative Neurotronics Inc. Both devices are used to address foot drop in patients with neurological conditions and can be used in patients with MS.

WalkAide Sensors on the WalkAide
The sensors are pictured on the right. WalkAide (left) consists of a battery-operated portable electrical stimulator, two electrodes, electrode leads and a cuff that holds the device in place below the knee.
Images reprinted with permission of Innovative Neurotronics.

Lower Extremity NeuroProsthesis

The Lower Extremity NeuroProsthesis is a custom-made device consisting of a portable neuromuscular stimulator, a Lycra-spandex sleeve that fits around the lower leg and a heel switch. The device has been available for several years and is part of Bioflex’s Wearable Therapy line.

“Lower extremity neuroprostheses are similar to orthoses but obviously greatly different,” said Philip Muccio, CPO, president and founder of Bioflex Inc. and Wearable Therapy. “I like to use the term neuroprostheses to define this technology. Neuroprostheses are devices that electrically interact with the nervous system and they do so to replace or substitute for lost neurological function.”

In patients with MS who still have the ability to contract their muscles and walk, the Lower Extremity NeuroProsthesis addresses foot drop by using FES. Because the device fits around the lower leg and not the foot, the device does not require special shoes or adaptations.

“When you begin fitting a device like a neuroprosthesis, you see patients light up because for the first time in perhaps years, their muscles are being activated and being used in a more physiological way. Their gait becomes more fluid and normal. Patients are interested in what their own body can still do, and I think that plays well into their psyche,” he said.

To learn how to fit the device, orthotists must attend a 3-day course. The first day encompasses background information that includes the physiology of electrical stimulation, because Muccio noted there are differences in how electrical stimulation contracts a muscle and the way the brain contracts a muscle. The remaining 2 days of the course consist of hands-on lab experience in which orthotists learn how to apply the technology and how to devise a variety of neuroprostheses.

“It is not exactly the mold that you are taught. When learning in school to devise an orthosis, you are looking at things that support the body,” he said. “In this case, you are looking much deeper into the body and trying to figure out how to make the body work better, and that is a completely different mindset. It does help you to think more in terms of improving patient outcomes.”

Potential candidates for the Lower Extremity NeuroProsthesis first undergo a muscular evaluation that assesses the hip flexors and abductors, knee extension and flexion, ankle dorsiflexion and plantarflexion and eversion and inversion. Patients are then tested to determine whether they are responsive to electrical stimulation, Vales said. He has been fitting patients with the Lower Extremity NeuroProsthesis for approximately 2 years.

“The O&P field has not looked at this or adopted this to any great extent, but since training people, I have been rather surprised by the enthusiasm,” Muccio said. “We are excited about making this technology almost the third leg to O&P. This branch of what I call neuroprosthetics is the 21st century direction that I believe O&P will go, and it has a broad spectrum of what it can do. It is not just a technology for foot drop. We can now devise neuroprosthetics systems for any muscle affected by CNS disorders.”

FreeStep FreeStep
FreeStep activates the dorsiflexor muscles throughout the swing-phase of gait and at heel-strike. Spasticity is suppressed by a neuromechanism known as reciprocal inhibition.
Images reprinted with permission of Bioflex Inc. and Wearable Therapy.


The WalkAide consists of a battery-operated portable electrical stimulator, two electrodes, electrode leads and a cuff that holds the device in place below the knee. The device, which has been available since 2006, uses an accelerometer which Innovative Neurotronics calls a tilt sensor in combination with Bluetooth wireless technology.

“The WalkAide is an active device. It is actually going to restore function and it is a whole rehabilitative treatment for MS,” Ouverson said. “It is going to actively promote rehabilitation or even recovery of that neuromuscular pathway, and that is what is so exciting with the WalkAide.”

Patients who are candidates for WalkAide undergo a brief evaluation in which they are assessed using a small handheld device with two electrodes. The electrodes are placed against the peroneal nerve in the leg just below the knee to ascertain dorsiflexion of the foot.

After it has been determined that the peripheral nervous system is intact and dorsiflexion is possible, three sets of data are collected. The first set of data is collected through a small heel sensor used only for the fitting and determines when the heel touches the floor and lifts off while the patient is walking with the WalkAide. The second set of data is collected by the tilt sensor and indicates where the leg is in space with reference to gravity to determine when the nerve should be stimulated. The third set of data is collected by the fitting clinician based on observing the patient walk during periods of stimulation and non-stimulation.

The WalkAnalyst computer software then analyzes the data from the heel sensor, the tilt sensor, and the clinician’s observations to determine when stimulation should be triggered. The results of the analysis then are directly fed wirelessly into the device so that when patients are wearing the WalkAide, they do not have to adjust anything because it has been preset in the clinic.

“Most patients never have to have it adjusted again,” Kufta said. “Some patients after having used it for some time particularly may improve their gait and therefore the parameters can be reset a little because now they are walking better than they were before. They would visit the clinician again who would go through the same test and the parameters would automatically be recalibrated.”

To learn how to fit the WalkAide, orthotists must attend a 2-day course. On the first day of the course, orthotists learn about the central and peripheral nervous systems, pathologies, and FES, and then they use the WalkAide themselves. The second day of the course consists of hands-on training with patient models. An advanced course is also available for clinicians who have already started fitting patients with the device and want to learn more.

“The WalkAide is myo-orthotic, so it is actually an orthotic device that is allowing the muscles to function, to do the work,” Ouverson said, who has fit or evaluated approximately 40 patients with the WalkAide. “Besides functional benefits such as safety and gait, there are therapeutic benefits such as increased mobility, increased strength and endurance, decreased energy expenditure and having that heel land first instead of the toe land first when they walk. We are increasing circulation to that area because of the muscle pumping action. We are helping to reduce osteoporosis because now that dorsiflexor is acting on the tibia bone, helping to maintain range of motion if not increase it to reduce the incidence of a plantarflexion contracture.”

After fitting a patient with the WalkAide, Ouverson sees the patient for follow-up at one week, 2 weeks, and then every 3 months to chart their progress. During the 3-month follow-up visit, patients complete a 10-meter timed walk test both with the WalkAide and then without to assess their progress.

Types of Multiple Sclerosis

Although MS is known for its unpredictability, several clinical patterns of the disease have been categorized, and the course of MS generally falls into one of the following four types. Within each category, the disease course can be mild, moderate or severe.

Relapsing-remitting MS

In this type of MS, which affects approximately 85% of patients, relapses, also known as exacerbations, flare-ups or attacks, are the predominant feature. Relapses last anywhere from days to months and are characterized by new symptoms or acute worsening of old symptoms. Patients then experience periods of partial or complete recovery or remission, which can occur gradually or almost instantly, and during periods of remission, there is no progression of the disease. Relapsing-remitting MS typically affects young adults in their 20s to 30s, and twice as many women as men have this form of MS.

Primary-progressive MS

This category of MS occurs more rarely, affecting approximately 10% of patients. The disease course of primary-progressive MS is one of slow, steady progression from onset, with no periods of relapses or remissions. Patients may, however, experience occasional plateaus and minor improvements in symptoms. This form of MS usually occurs in individuals in their late 30s and early 40s, and affects both men and women equally.

Secondary-progressive MS

This phase of MS follows relapsing-remitting MS and is characterized by a steady worsening of the disease course. Relapses become longer and are followed by shorter remissions in which there is no real recovery. Roughly 50% of patients with relapsing-remitting MS develop secondary-progressive MS within 10 years of being diagnosed. This percentage increases to 95% after 25 to 30 years.

Progressive-relapsing MS

Affecting only approximately 5% of patients, this type of MS is characterized by steady progression and worsening of the disease with acute flare-ups and only rare, if any, remissions. Unlike relapsing-remitting MS, progressive-relapsing MS is characterized by disease progression in the periods between exacerbations.

For more information:

  • Hamler B. Exercises for Multiple Sclerosis. Long Island City, NY: Hatherleigh Press; 2006.
  • Hill BA. Multiple Sclerosis Q&A. New York, NY: Avery; 2003.
  • Holland NJ, Halper J. Multiple Sclerosis. New York, NY: Demos Medical Publishing; 2005.
  • National Multiple Sclerosis Society. Just the facts 2006-2007. Available at Accessed April 25, 2007.

Reimbursement issues

As emerging technology, electrical stimulation devices are beginning to be covered by health care insurance, but not yet by Medicare and Medicaid.

Innovative Neurotronics is working with the Centers for Medicare and Medicaid Services and third-party insurers to get the WalkAide reimbursed, Kufta said. In addition, he noted that clinical trials are ongoing at five and soon seven major medical centers in the United States. The results of these clinical trials, which are expected to be completed before the end of the year, will be used to make the case for coverage and reimbursement.

“There is a large range of potential uses of this in patient populations that orthotics and prosthetics fitters are dealing with now, so I think you are going to be hearing more of this as a stand-alone technology and also as an accompaniment in hybrid treatments of many clinical problems, such as the combinations of bracing and FES and surgical procedures,” Kufta said.

For more information:

Mary L. Jerrell, ELS is a correspondent for O&P Business News.

Editor’s note:
This story includes a small representative sample of individual companies and products. O&P Business News does not intend to promote individual companies or their products, nor to achieve an industry-wide consensus on the issue. Companies contacted in developing this story were randomly selected.

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