Functional electrical stimulation (FES) is a treatment that applies small electrical charges to the leg to improve mobility in people who have difficulties with walking arising from damage in their brain or spinal cord. In MS it is mostly used as a treatment for foot drop.

What is FES?

Functional electrical stimulation (FES) uses small electrical signals to stimulate the nerves in the leg, causing the muscles to contract and produce a movement that can help walking. In MS, the most common use of FES is as a treatment for foot drop where disruptions in the nerve pathways between the legs and brain which means the front of your foot cannot be lifted to the correct angle when walking.

An FES device consists of a control box, about the size of a pack of cards, which is either worn on your leg or around your waist. Connected to this control box is a sensor worn in your shoe (heel switch) which detects pressure changes as the foot starts to move, then electrodes attached to the skin below the knee apply the electrical signals to the leg. If you have foot drop, these signals can, for some people, help lift the foot to the correct angle for taking a step and prevent it dragging on the ground.

There is also a version of FES available that uses a nerve stimulator that is surgically implanted. However the versions that are worn are much more commonly used, and wired as well as wireless versions are now available.

As well as being a treatment for foot drop FES can also be used in rehabilitation, complementing physiotherapy techniques, often to assist with movements in muscles that have become weak. This allows you to build up strength and range of movement. This may also help with reducing spasticity and sometimes in reducing swelling, depending on the cause.How FES works

Who can use FES?

If you have difficulty with walking due to foot drop, you may benefit from FES. However, as FES stimulates the existing nerves in the legs, it is important that your nerve fibres between the spinal cord and the muscles are not damaged. To be suitable for the treatment, you need to be able to walk, even if only for a few metres with a stick or crutch.

Typically you will have an initial assessment that lasts for about an hour to see if you are suitable for treatment and if you respond to the FES stimulation. If you do respond then you can start the treatment process. A health professional will set up the device with you and teach you how to use it. At first you may find it difficult and time consuming to put the device on and position the pads correctly, but this becomes easier with practice.

FES treatment can continue for as long as it is appropriate, as FES is safe to use in the long-term and some people have used FES for many years.

Although FES can be used to make the most of your walking ability, it does not improve the signal your nerves send without the stimulator and it does not protect your nerve pathways from further deterioration. This may mean there will come a point when FES is no longer effective for you.

Even though people are carefully assessed before treatment, some find they get no benefit from FES or they find it difficult to use the stimulator effectively. Some people have difficulty placing the electrodes precisely, especially if they experience numbness in their fingers, for example. Others do not like the sensation of the stimulation.

If FES is not suitable for you, you may be able to try an alternative treatment such as a support, ankle foot orthotic (AFO) or physiotherapy.  

What are the benefits of FES?

Research and experience has shown that treatment with FES produces a more normal walking pattern, enabling people to walk faster, further and with less effort. It can also help build confidence in walking and increase independence as well as reducing the risk of trips and falls.

What side effects could I get with FES?

The electrical stimulation causes a tingling 'pins and needles' or buzzing sensation on the skin. Ensuring that wires and pads are in the correct positions can help minimise some of these sensations. For most people this is not a problem, but some can find the effect uncomfortable and some may not want to continue using the FES.

Very occasionally people find that the stimulation or the electrodes causes irritation of their skin. Using hypoallergenic electrode patches or asking your health professional about changing the type of stimulation that is used can often solve these problems.

How do I get FES treatment?

In January 2009, NICE (National Institute for Health and Clinical Excellence) issued guidance that FES can be offered routinely as a treatment option for people with foot drop caused by damage to the brain or spinal cord if the health professional considers it is appropriate. Decisions about whether to fund the cost of FES are taken by local NHS bodies, such as the local Clinical Commissioning Group (CCG) or Health Board.

An assessment by a health professional trained in the use of FES is required to ensure that the treatment will be suitable for you. The health professional will also teach you to place the pads correctly so the FES works as well as possible and that the equipment is being used most effectively.

The National Clinical FES Centre in Salisbury provide services across the south of England and the use of FES is growing, with an increasing number of other centres offering the treatment around the UK. To access treatment you usually need to be referred to a FES service by your GP, MS nurse or neurologist. You can find out about FES clinics near you on the MS Trust's map of MS services.


  • Odstock Medical Limited is the NHS company that was formed by the department of Salisbury District Hospital that developed the treatment and which supplies several FES devices.
  • Bioness are an American company who make several FES devices.
  • WalkAide is an American FES device that is available in the UK from Trulife.
  • Otto Bock make several FES devices.

FES research

The MS Trust has funded two research trials at Salisbury District Hospital. The first investigated the effect of FES on walking and quality of life. This found that FES is effective in improving walking, particularly in enabling greater distance to be achieved. However, exercise alone also made a significant difference to walking and it was concluded that the combination of these treatments may prove to be a more effective means of improving mobility.

A second study involved 64 people with secondary progressive MS assigned to either a group using FES or a group who received physiotherapy exercises. The FES group showed better results on the Canadian Occupational Performance Measure, a scale that measures how well people perform activities of daily living.  During the 18 week study, the FES group also experienced fewer falls than the exercise group.

Subsequent research into FES in MS has helped refine and improve the systems available, and explore new uses for the devices. There has been a preliminary study investigating the feasibility of using of FES in conjunction with robot support to improve hand and arm function in people with MS. The study only involved five women with MS, but showed that the system could be safe and effective to use, and further larger studies would be needed to investigate the potential benefits. 


  • Barrett CL, et al. A randomized trial to investigate the effects of functional electrical stimulation and therapeutic exercise on walking performance for people with multiple sclerosis. Multiple Sclerosis 2009;15(4):493-504. Summary
  • Esnouf JE, et al. Impact on activities of daily living using a functional electrical stimulation device to improve dropped foot in people with multiple sclerosis, measured by the Canadian Occupational Performance measure. Multiple Sclerosis 2010;16(9):1141-1147. Summary
  • Street T, et al. Effectiveness of functional electrical stimulation on walking speed, functional walking category, and clinically meaningful changes for people with multiple sclerosis. Archives of Physical Medicine and Rehabilitation 2015;96(4):667-672. Summary
  • Sampson P, et al. Using functional electrical stimulation mediated by iterative learning control and robotics to improve arm movement for people with multiple sclerosis. IEEE Transactions on Neural Systems and Rehabilitation Engineering 2016;24(2):235-248 Summary
  • National Institute for Health and Clinical Excellence. Functional electrical stimulation for drop foot of central neurological origin. London: NICE; 2009. Full guideline

Last updated: 2 June 2016
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