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Functional Electrical Stimulation (FES)

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Functional Electrical Stimulation (FES)

The National MS Society frequently fields questions about functional electrical stimulation (FES) — usually in relation to the products WalkAide from Innovative Neurotronics, NESS L300™ from Bioness® and the Odstock Dropped Foot Stimulator from Odstock Medical Limited in the United Kingdom.

Following is some information about what scientists know — and what they still need to learn — about the effectiveness of these devices for people with MS.

Overview of FES devices

Most MS rehabilitation specialists recommend physical therapy and, if needed, a brace or “ankle foot orthosis” to treat foot drop. The brace, which is usually made of plastic, is worn around the lower leg and foot. It supports the ankle and holds both foot and ankle in a flexed position.

Two new devices — the WalkAide and NESS L300 — are now on the U.S. market to alleviate foot drop. They work by sending low-level electrical impulses to the peroneal (sometimes called fibular) nerve, which signals leg muscles to lift the foot. Seen as easier to wear and more convenient by many users, they are also a great deal more expensive — about $5,000-$6,000 — and typically not covered by insurance.

The FES products used for foot drop are reputable, but not everyone with MS experiences positive results. For the devices to work, the peroneal nerve must be capable of sending a signal and the muscles must be capable of receiving it. In MS, a variety of complications may prevent this from happening.

Since scientific studies on FES and foot drop have focused primarily on people who have had a stroke, we do not have enough data yet to know how broadly useful such products might be for people with MS as a whole.

Prospective users need to check out the terms associated with product trials. The Society has received reports of patients losing their deposits when they wanted to return the devices after finding them ineffective.

National MS Society Resources on Walking and FES

Medical Literature about FES

  • Miller and colleagues (Archives of Physical Medicine and Rehabilitation, 2017) reviewed 19 studies on the effectiveness of Functional electrical stimulation (FES) technology for improving walking speed in short and longer distance performance tests. Across these studies, the FES device showed significant improvement in gait speed in short walking tests but not in longer walk tests. The studies also showed that the FES device was useful as long as it was in use, but didn’t provide improvement in walking speed (therapeutic benefit) when the device wasn’t being worn by people with multiple sclerosis.
  • In a study involving 20 adults that looked at the differences in the energy cost, efficiency and effort required to walk with  an ankle foot orthosis (AFO) and an FES device, Khurana and colleagues (American Journal of Physical Medicine and Rehabilitation. 2016) found that individuals using the FES reported having to exert themselves less to walk than those who were using an AFO. However, the actual energy expenditure and efficiency measurements were found to be  no different between the two devices. 
  • 20 people with MS-related foot drop participated in a study to determine whether the FES device improved walking speed and reduced energy expenditure.  Miller and colleagues (Disability and Rehabilitation Assist Technology. 2016) found that FES is effective in improving the speed and oxygen cost of walking at a slow walking speed of less than 0.8 meters per second (about 1.8 miles per hour), but does not seem to improve speed or reduce energy cost at faster speeds. Of note; the average walking speed of an adult is approximately 3.0 miles per hour on a flat surface.
  • Gervasoni and colleagues (PM & R - the journal of injury, function and rehabilitation, 2016) studied the effectiveness of FES in reducing falls in 5 people with MS over 8 weeks. The use of FES was found to reduce the number of falls and improve walking. A specific effect at the ankle joint was observed; the FES worked to increase the foot clearance during the swing phase of gait – which meant that FES users were less likely to catch their toes on the ground or trip. However, the use of FES did not reduce the amount of energy required to walk. 
  • This large study measured the effectiveness of FES in 187 subjects for 5 years.  Street and colleagues (Archives of Physical Medicine and Rehabilitation. 2015) found an increase in walking speed to 0.11meters per second or 0.24 mph.  After 20 weeks, treatment responders displayed a 27% average improvement in their walking speed. Overall functional walking category was maintained or improved in 95% of treatment responders. 
  • Bulley and colleagues (Disability and Rehabilitation Assist Technology. 2014) explored the impact of AFO or FES on 10 subjects with foot drop from MS.  Participants reported that benefits of AFO and FES use outweighed the drawbacks. The benefits reported included reduced fatigue, improved gait and reduced tripping and falling. Common barriers included finding the devices cumbersome, uncomfortable, and inconvenient, with some psychological barriers to their use.
  • This study was undertaken to determine the effects of a 2-week FES Home Assessment Program on gait speed, perceived walking ability, and quality of life (QOL) on 19 participants with MS-related footdrop. Downing and colleagues (International Journal of MS Care. 2014) showed a significant decrease in time to complete the 25 foot walk test. These results suggest that use of FES can significantly improve gait speed, decrease the impact of MS on walking ability, and improve QOL in people with MS-related footdrop over a short period of time. 
  • Twenty participants with MS participated in this study that compared two different FES devices; the Odstock Dropped Foot Stimulator (ODFS - only available in Europe) and Walkaide (WA). Miller and colleagues (Disability and Rehabilitation Assist Technology. 2014) had the participants walk for 5 min around an elliptical 9.5 meter course at their preferred walking speed -- once with ODFS, once with WA and once without FES. Results showed a significant increase in walking speed with the ODFS and an almost significant increase with the WA as compared with walking without an FES device. There were no differences between the ODFS and WA in terms of the energy cost of the exercise.
  • This study examined the effect of FES on foot drop in combination with physical therapy core stability exercises. Taylor and colleagues (Neuromodulation Journal of the International Neuromodulation Society. 2014) studied 28 people with secondary progressive multiple sclerosis and unilateral dropped foot. Results showed that FES improved walking speed and Rivermead Observational Gait Analysis (ROGA) scores, whereas physical therapy alone did not. Adding gluteal stimulation further improved the ROGA score. Both FES and physical therapy reduced falls, but adding FES to physical therapy reduced them further. Adding gluteal stimulation further improved gait quality, and physical therapy may have enhanced the effect of FES, but FES had the dominant effect.

 

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