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Functional electrical stimulation in multiple sclerosis

Catherine Johnson
Department of Medical Physics at Salisbury District Hospital

Open Door - November 2002 pages 6-7

The term Functional Electrical Stimulation (FES) describes the use of an electrical stimulator to make daily activity easier in a number of conditions. For people with MS, FES can be used to make walking easier and safer. A FES service was set up at the Department of Medical Physics at Salisbury District Hospital in 1996. Since then about 300 people with MS have been seen, from all parts of the UK.

How does FES work?

The stimulators have been designed and developed at Salisbury by the clinical engineers in the Department. They are operated by a 9 Volt (PP3) battery and produce electrical impulses which are used to stimulate the nerves in the leg. This causes muscles to contract, even when there are conduction problems from the nerves in the brain and spinal cord. The muscle contraction produces a movement that can be used to help walking. The timing of stimulation is controlled by a pressure switch worn in the shoe.

An Odstock Dropped Foot Stimulator

1. an Odstock Dropped Foot Stimulator

The most frequently used stimulator is called the Odstock Dropped Foot Stimulator (ODFS). The first photograph shows an ODFS with the footswitch and the electrodes that pass the current through the skin to the nerves. The stimulator itself is about the size of a pack of playing cards. The second photograph shows how the stimulator is usually set up to help someone with a dropped foot - the stimulator works to help foot clearance, preventing the toe from catching when taking a step forward.

A stimulator in place on the patient's leg

2. a stimulator in place on the patient's leg

How can FES treatment be arranged?

Patients need a medical referral from either their general practitioner, or their consultant to be seen, and for NHS funding to be agreed. People who have been unable to secure NHS funding and who are able to pay for their treatment have been seen on a private basis.

As FES is still a fairly new treatment, you may find that not all clinicians have heard of it. The Department's website is a good source of information for both patients and clinicians. Our address is www.salisburyfes.com.

Referrals should be sent to:

Professor Ian Swain
Head of Department
Department of Medical Physics
Salisbury District Hospital
Salisbury
Wiltshire
SP2 8BJ

The Department's telephone number is 01722 336262 extension 4060.

All patients are booked for an initial assessment to see if FES is likely to be helpful, as it does not suit everybody. Some people dislike the sensation, and sometimes spasm is set off by stimulation. In the majority of cases, however, the sensation is well tolerated, and spasticity is reduced with stimulation.

We have found that people need to be able to stand up by themselves, and be able to take a few steps (with a walking aid if required) to be able to benefit from using FES. Many of the people using FES are able to walk further than this.

If I am suitable for FES, what does the treatment involve?

If FES is found to be helpful, patients are given two appointments to be set up with the stimulator. These appointments last an hour each, and are usually held on consecutive days. You will be seen by either a chartered physiotherapist who specialises in neurology or by a clinical engineer. They will adjust the stimulator carefully to get the best response, and teach you how to set it up for yourself. Many people find that they can use the stimulator independently although some people find that some assistance is helpful.

Follow-up appointments are then made at six weeks, three months and then every six months while you are using the stimulator. It is very important that you are checked at intervals, so that any adjustments can be made, and your progress monitored. Many people the stimulator all day, turning it on when they are walking. Some people use it for part of the day only. Everyone is encouraged to telephone the Department if any questions or problems arise in between appointments.

Are there any tests involved?

The Department uses some simple tests to monitor each patient's response to stimulation. These include observing someone's walking pattern, timing walking speed and measuring the effort of walking. These are measured both with and without stimulation.

Are there any risks or side effects from the treatment? If anyone has a cardiac pacemaker or unstable epilepsy, then it may not be possible to use FES. Modern pacemakers can often be used quite safely with FES, but this is carefully assessed.

The most common side effect of using FES is skin irritation. The clinicians in the Department will give you detailed advice on how to look after your skin when using FES to reduce the likelihood of this happening, and will tell you what to do if it does occur.

What are the benefits of using FES? The most frequent benefit of FES to people with MS is that the effort involved in walking is noticeably reduced. Sometimes this means that people can walk a little further before getting tired. As foot clearance is better, walking is often steadier and safer, and the tendency to trip or fall is much reduced. FES also usually has a positive effect on muscle spasticity or stiffness.

Is treatment with FES only available at Salisbury District Hospital? No, there are a number of satellite clinics around the UK that may be more convenient for you to attend. The Department holds list of registered practitioners who they have trained to use FES - these are mainly chartered physiotherapists. It may be possible to be set up and treated by a registered practitioner in your area.

Are there any other stimulators? Yes, the Department has developed a stimulator with two channels, so that another part of the body can also be stimulated when walking. For example, if both feet are affected, electrodes may be worn on both legs to help foot clearance. Where someone has weakness just on one side of the body, muscles around the thigh or hip may be stimulated by the second channel.

There are also exercise stimulators that are just used at rest to maintain or improve muscle activity, to reduce spasticity and gently stretch tight muscles and tendons.

Where can I find out more information? Much more can be found out about FES on the Department's website, including information about clinics, the Department's research activity and links to other sites. The website can be found at www.salisburyfes.com.

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