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By Tommy Sutor, MS, CSCS

Former Program Director at Push to Walk NJ, currently pursuing a PhD in movement science exploring the coordination between walking and breathing.

In October, a scientific article written by researchers from the University of Louisville and Frazier Rehab Institute presented with some pretty incredible results; a man who had been paralyzed from a spinal cord injury for over 4 years had regained the ability to voluntarily move his legs and stand. These results came after another study performed at UCLA in 2015, which reported similar results, of the return of voluntary movement at least two years after a spinal cord injury. Importantly, all the participants in these studies had been diagnosed with “complete” spinal cord injury, meaning they had no ability to move or feel any part of their body below their injury. In both studies, the movements were not perfect, and were not always useful to the study participants in everyday life. Nonetheless, they served as important proof-of-concept studies, showing that return of movement after a spinal cord injury is at least possible.

How is this possible? Both studies involved long periods of physical rehabilitation and exercises. What set both of these studies apart is they employed methods of electrically stimulating the spinal cord of the research participants, giving the participants more “bang for their buck” from the exercises they were doing. In the Louisville study, an epidural stimulator was used, which is a device that is actually surgically implanted inside the spine to stimulate nerves in the spinal cord. In the UCLA study, a transcutaneous stimulator was used; transcutaneous means “over the skin”. Thus, this stimulator used adhesive pads on the lower back and the abdomen, combined with a special electrical wave form that could stimulate nerves in the spinal cord from outside the body.

In both studies, the electrical stimulation to the spinal cord was the crucial ingredient needed to enable voluntary movement after it had been lost due to spinal cord injury. In the words of Dr. Reggie Edgerton, who has been involved in many transcutaneous and epidural stimulation studies, the electrical stimulation excites the spinal cord, and acts as a “hearing aid”, allowing nerves in the spinal cord to “hear” the intention to move that comes from the brain.

As studies like this one have been released, many people have wondered, “Can riding an FES bike do the same thing?” This is a reasonable question – after all, an FES bike uses electrical stimulation to excite nerves in your body to make your muscles contract. However, many people with complete spinal cord injuries who diligently use their FES bike know that, in most cases, the use of an FES bike alone is not enough to return the ability to voluntarily move one’s legs. But why is that true, when both FES cycling and spinal cord stimulation involve electrical stimulation?

To understand this better, let’s explore the two main ways movement occurs: reflexes and/or the voluntary intent to move. In a reflex, like when a doctor hits below your kneecap with her reflex hammer and your leg kicks out, the reflex hammer hitting below your kneecap activates sensory nerves (the green circles and lines in the drawings below) in your leg. These sensory nerves send “activation” signals to other nerves in your spinal cord (represented by the purple box), including motor nerves (the red stars in the drawings). These motor nerves send long projections out from your spinal cord, called axons (the red lines that go to the muscle), to your leg muscles, and your leg muscles contract, briefly Comparisonkicking your leg out in front of you. Similarly, when a person voluntarily intends to move, this intent originates in the brain; nerves in the brain send signals down the spinal cord (represented by the blue arrow and lines) to other nerves, including motor nerves, which then send signals down their axons to a muscle to make it contract.

FES bikes use a specific type of electrical wave form to target just the axons that project out from motor nerves. By placing FES pads over a specific muscle, the electrical wave form will activate those motor nerve axons directly (as seen by the lightning bolts in drawing “A”). The intention of the FES bike is to skip over the sensory nerves and nerves from the brain and provide enough electrical stimulation to a motor nerve axon to bring it above a certain threshold to induce a muscle contraction, whether the user is thinking about moving or not.

Spinal cord stimulation, whether epidural or transcutaneous, works quite differently. Because of the waveform and the location where it’s applied, spinal cord stimulation actually activates all the nerves in and around the spinal cord, including both sensory and motor nerves. An even bigger difference between spinal cord stimulation and FES, however, is that with spinal cord stimulation, the intention is to provide enough electrical stimulation to be just below the threshold that will induce a muscle contraction (represented by the smaller lightning bolts in drawing B, now near all the nerves in the spinal cord). Why is that? The idea is, the spinal cord stimulation plus the voluntary intent to move/reflex activation together cause the motor nerve axon to fire and the muscle to contract. As was mentioned earlier, the intention of spinal cord stimulation is to enable motor nerves to “hear” activation signals from sensory nerves or brain nerves.

Despite promising results, spinal cord stimulation studies are still in their infancy in humans, and it will take much more safety data and many years of development before spinal cord stimulation is used regularly for spinal cord injury rehabilitation. Because of this, almost all rehabilitation professionals agree that people with a spinal cord injury should do everything they can to keep their bodies in optimal condition to be ready for better medical treatments in the future. For example, spinal cord stimulation may benefit people more if they already have strong muscles and cardiovascular systems when they begin using it. Thus, people who are already using FES bikes to keep their muscles and cardiovascular system in shape should continue doing so, with the added knowledge that you are preparing your body for even better things to come. If you don’t currently use an FES bike but want to start, the MyoCycle is a low-cost, high-quality option that I highly recommend.

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YMCA Receives New MyoCycle Therapy System to Help Locals with Disabilities

Gainesville, FL – December 27, 2017 – MYOLYN, a medical technology company dedicated to improving health and human performance, announced today that the YMCA in Batavia, NY has purchased the MyoCycle Pro FES cycling therapy system for its members with neurological disabilities.

The MyoCycle Pro uses Functional Electrical Stimulation (FES) technology to allow disabled individuals to exercise and maintain a healthier lifestyle.

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The University of Miami is currently conducting research on the effects that cycling with functional electrical stimulation (FES-cycling) has on people with spinal cord injury. The research team, led by Mark Nash, PhD, FACSM, and his student, David McMillan, is interested in how energy expenditure and fuel partitioning, as well as cardiac output, are affected by FES-cycling exercise performed on two different FES bikes: the MyoCycle and the RT300.

So far, the team has completed experiments with four men with various levels of spinal cord injury, and the results were recently presented during a poster session at the American Spinal Injury Association (ASIA) conference in Albuquerque. The full poster is presented below, but the concluding points are as follows:

  • Moderate stimulation intensity FES cycling qualifies as “low intensity” aerobic exercise according to authoritative guidelines (aerobic effect similar to walking).
  • The MyoCycle relies less on carbohydrate fuels and more on fatty fuels at the selected moderate stimulation intensity.
  • The MyoCycle promotes a more extensive excessive post-exercise oxygen consumption (EPOC) for 30 minutes after termination of stimulation.
  • The greater gross mechanical efficiency (23.3% as opposed to only 16.7% from the RT300) observed for the MyoCycle may have implications for more substantial sparing of muscle fatigue accompanying FES cycling.

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What do these results mean?

These are still preliminary results, but there are three key take-away points:

    1. Both the MyoCycle and the RT300 can give people with spinal cord injury a good workout.
    2. The unique characteristics of the MyoCycle cause some interesting positive effects not seen when using the RT300 (more fat burn and greater EPOC).
    3. The MyoCycle is significantly more efficient than the RT300 (more cycling power output for the same amount of calories burned).

The research team also collected some interesting cardiac output data from the study, but these results won’t be presented until the American College of Sports Medicine (ACSM) annual meeting at the end of the month.

MYOLYN is committed to supporting research into the benefits of FES for people with neurological disorders. Sign up for our newsletter to keep up to date with the results!

If you’d like to learn more about how the MyoCycle can help someone with paralysis to get a great workout, click here!

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Thursday, 04 May 2017 18:36

What is spasticity?

Spasticity is one of the many secondary health effects caused by paralysis. People with a spinal cord injury, stroke, cerebral palsy, and multiple sclerosis most often have trouble with spasticity, but it can affect anyone with an upper motor neuron lesion. That includes a wide range of neurological disorders and injuries, and it means that millions of people are affected by spasticity.

When most people think of spasticity, they imagine simple muscle spasms, where a muscle twitches involuntarily. However, spasticity, also known as spastic hypertonia, can be more accurately defined as “disordered sensori-motor control, resulting from an upper motor neuron lesion, presenting as intermittent or sustained involuntary activation of muscles’’ [1], and the effects of spasticity can range from slight muscle stiffness to intense, uncontrollable muscle spasms that can literally launch someone out of their chair.

What causes spasticity?

Upper motor neuron lesions cause spasticity in much the same way that they cause paralysis and loss of feeling – by disrupting communication between the brain, the spinal cord, muscles, and the sensory system (sensory organs in the skin, muscles, tendons, etc.). Normally, if you want to relax a muscle, you only have to think about it, and your brain will communicate with your muscles through your spinal cord to make them relax. But if your brain or spinal cord is damaged, your muscles never get the message to relax. For this reason, if anything tells your muscles to activate, like a reflex that makes you pull away from something hot, the activation is often exaggerated or never stops. Spasticity can be triggered by movement, pain, discomfort, posture, and even other medical problems like urinary tract infections and pressure sores.

What does spasticity look like?

Many people with spasticity have increased muscle tone, meaning that some of their muscles never relax fully and are always somewhat contracted. This increased tone, also known as hypertonia, can range from mild and uncomfortable to severe and debilitating, like rigidity. Hypertonia is most commonly seen affecting the upper limb, resulting in a constantly flexed elbow, bent wrist, and/or clenched fist.

hands and spasicity

Figure 1: Presentation of spasticity in the upper limb.

The other common presentation of spasticity is hyperreflexia (exaggerated reflexes). When a reflex arc is activated in someone with spasticity, like when the patellar tendon is struck or you touch a hot stove and recoil, oftentimes the reflex will be exaggerated. In extreme cases, the reflex will repeat itself over and over again, echoing through the nervous system, which is known as clonus. Check out this video to see what hyperreflexia and clonus look like.

Pros and cons of spasticity

While spasticity is a symptom of a neurological disorder, it’s not always a bad thing. The table below lists some of the pros and cons of spasticity.

Pros Cons
Stiff muscles can help with some activities, like transferring from a wheelchair  Stiff muscles can hinder other activities, like getting dressed or brushing your teeth
     Controlled reflex spasms can help with some activities, like standing & grasping                       Uncontrolled reflex spasms can hinder other activities and lead to injury                  
   Hypertonia and spasms work the muscles, preventing atrophy & bone density loss                              Spasticity can be uncomfortable and even painful
     Metabolic requirements of spasms can improve blood circulation and breathing           Extreme hypertonia can lead to joint contractures and pressure sores
      Spasticity can be a warning sign that something else is wrong, like an infection                Extreme hyperreflexia can lead to injuries from collisions and falls

For more on the pros and cons of spasticity, check out this video from the University of Washington.

Managing spasticity

If the cons of spasticity outweigh the pros, then treatment may be necessary. There are several options for managing spasticity, each with its own pros and cons:

  • Surgery
    • Surgery is sometimes used as a last resort to release contractures, lengthen muscles, or reshape joints.
    • Pros: Permanent solution
    • Cons: Irreversible, painful, potentially dangerous, expensive
  • Implanted pump
    • An intrathecal pump can be implanted in the body and programmed to automatically deliver anti-spasm medication right where it’s needed.
    • Pros: Precise and low-dose so reduced side effects, reversible, refillable
    • Cons: Requires surgery, can malfunction, may cause infections, expensive
  • Injections
    • Chemicals can be injected directly into the muscle to block nerves and eliminate spasticity.
    • Pros: Only needed once every few months, directly targets the spastic muscles
    • Cons: Effectiveness diminishes over time, expensive
  • Medications
    • Medications can be taken orally or transdermally (through a patch) to manage spasticity.
    • Pros: Non-invasive, easy to manage, more affordable
    • Cons: Requires higher doses and affects the whole body with increased side effects
  • Stretching and exercise
    • The majority of time in inpatient rehab following a spinal cord injury is spent on range of motion (stretching) and strengthening exercises [2], which have a positive effect on spasticity.
    • Pros: Easy to do for some people, strengthening can improve function, most affordable
    • Cons: Time-consuming, can be difficult without assistance or special equipment
  • Electrical stimulation
    • Electrical stimulation can activate paralyzed muscles, enabling someone to exercise muscles that they otherwise could not.
    • Pros: Reduces number of spasms, best way to exercise paralyzed muscles, can have beneficial side effects, can be done without much time and effort, affordable options available
    • Cons: Can strengthen muscles, making spasms stronger; may not work well for everyone; can be expensive and complicated

Electrical stimulation and spasticity

There is a lot of confusion out there as to how electrical stimulation can be used to manage spasticity. Arjan van der Salm, a researcher from the Netherlands who wrote his doctoral dissertation on managing spasticity with electrical stimulation, provides a great analysis in his journal paper published in 2006 [3]. He demonstrated that electrical stimulation does not reduce spasticity, but it does relax spasms, meaning that the muscle will spasm less for a period of time, usually for several hours after stimulation. This can be achieved by either stimulating the spastic muscle itself, or by stimulating its antagonist. For example, if a person’s calf muscles (triceps surae) are spastic, electrical stimulation can be applied to the calf muscle or to the shin muscles (tibialis anterior), and either will relax the spasms. Van der Salm showed that stimulating the spastic muscle itself was most effective in relaxing spasms, probably because the stimulation fatigues the muscle and improves blood circulation to the muscle.

The takeaway here is that electrically stimulating a muscle can prevent spasms for several hours afterwards, so it can be used as needed to manage spasticity.

Final thoughts

There are many different factors to consider when choosing how to manage spasticity. The cause of spasticity, your situation and medical condition, and other factors like financing and support can all affect your decision. At the end of the day, a combination of methods will probably be best. For example, many people are fine with a low dose of medications combined with regular stretching and strengthening. It’s always best to consult your physician to find out what approach will be best for you.

For more information about spasticity, check out the resources below.

If you know someone who could use some help in managing spasticity, please share this article with them using the social media links at the top of the post.

The MyoCycle combines electrical stimulation with range of motion and strengthening exercise and is cleared by the FDA for general rehab for:

  1. Relaxation of muscle spasms
  2. Prevention or retardation of disuse atrophy
  3. Increasing local blood circulation
  4. Maintaining or increasing range of motion

To learn more about managing spasticity with the MyoCycle, click here.

Resources

WebMD: Spasticity

Cleveland Clinic: Spasticity

National MS Society: Spasticity

MedlinePlus: Caring for muscle spasticity or spasms

UAB-SCIMS: Spastic Hypertonia Spasticity following SCI

CareCure: FAQ about implanted baclofen pumps for managing spasticity

References

[1] Pandyan AD, Gregoric M, Barnes MP, Wood D, Van Wijck F, Burridge J, Hermens H, Johnson GR. Spasticity: clinical perceptions, neurological realities and meaningful measurement. Disability and Rehabilitation 2005;27(1/2):2-6.

[2] Taylor-Schroeder S, LaBarbera J, McDowell S, Zanca JM, Natale A, Mumma S, Gassaway J, Backus D. The SCIRehab project: physical therapy treatment time during inpatient spinal cord injury rehabilitation. The Journal of Spinal Cord Medicine 2011; 34(2):149-161.

[3] van der Salm A, Veltink PH, Ijzerman MJ, Groothius-Oudshoorn KC, Nene AV, Hermens HJ. Comparison of electric stimulation methods for reduction of triceps surae spasticity in spinal cord injury. Arch Phys Med Rehabil 2006; 87:222-228.

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Among people with spinal cord injury, who is most likely to benefit from functional electrical stimulation (FES) therapy? That’s a great question that many researchers are asking in regard to a wide range of spinal cord injuries.

In a small study of 14 paraplegics wishing to participate in sports, researchers found that people whose spinal cord injury occurred above T-12 were more likely to benefit from FES-cycling therapy, and those with traumatic injury as opposed to infectious injury were the most likely to respond to FES-cycling therapy.

The Brazilian and French researchers published their findings in the European Journal of Translational Myology last fall.

In the study, the researchers aimed to examine the personal, clinical, structural, and functional characteristics of people with paraplegia interested in sports. They assessed all for responsiveness to neuromuscular electrical stimulation (NMES) by applying stimulation to the subjects’ leg muscles. They divided those whose muscles visibly contracted into the responsive group and those whose did not assigned to the non-responsive group.

In all, there were 14 volunteers, 3 men and 11 women between the ages of 23 and 56, who had been living with paralysis from 2 to 50 months. All participated in 16-sessions using surface NMES applied to the quadriceps and progressing to other muscle groups. The strength of contractions in response to NMES was measured on a scale from 0 to 5, where 3/5 was considered strong enough for movement against gravity.

The researchers found that all the volunteers who responded to NMES had spinal cord injuries above T-12, while among those who did not respond, half had injuries above T-12 and half had injuries below T-12 or the lumbar area. When they distinguished between spinal injury caused by trauma versus infection, they found that only one in the non-responsive group had spinal cord injury above T-12.

They concluded that paraplegics with traumatic spinal injuries above T-12 were the best potential candidates for FES-cycling therapy. According to the 2015 Annual Report by the National Spinal Cord Injury Statistical Center (NSCISC), 90% of people with spinal cord injury are injured at T-12 or above, meaning that 9 out of 10 people with spinal cord injury are likely good candidates for FES-cycling therapy.

The explanation for these results is that injury below T-12, or certain types of spinal cord infections, typically damage the peripheral nerves. Without intact peripheral nerves, NMES/FES cannot cause the muscles to contract, meaning that people with damaged peripheral nerves are not good candidates for FES-cycling therapy.

If you or a loved one may be a candidate for FES-cycling therapy, the MyoCycle Home may be right for you. It is the most affordable, easiest-to-use FES bike ever made, and it empowers people with muscle weakness or paralysis to get the best workout possible from the comfort of home.

Source: European Journal of Translational Myology, Sep 2016

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5128972/

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