Functional electrical stimulation
Geraldine Mann, Physiotherapist, Salisbury District Hospital
Open Door - May 2005 pages 6-7
What is functional electrical stimulation?
Functional electrical stimulation or FES is a form of treatment to aid mobility in people who have had damage to their brain or spinal cord. Small electrical impulses are used to excite the nerves that supply paralysed muscles. This activates those muscles enabling them to produce basic but useful movement. Self-adhesive patches (electrodes) are placed on the skin close to the nerve that supplies the muscle and are connected by leads to a stimulator that produces the impulses.
How can FES help walking?
The most common problem treated by FES is 'dropped foot'. This is the inability to lift the foot and toes when swinging the leg through during walking. This causes the toes to catch or the foot to drag on the ground unless an individual compensates in some way by bending the hip and knee excessively or by 'hitching' the hip by shortening the trunk on that side. Over time these compensations can lead to secondary complications such as muscle shortening, hip or lower back pain and poor balance, which can lead to falls and a loss of confidence.
Dropped foot is caused by weakness or paralysis of the muscles that lift the foot and possibly tightness or spasticity of the calf muscles. Stimulation is applied to the muscles at the front of the leg by the Odstock Dropped Foot Stimulator, the only type of stimulator available which is capable of correcting dropped foot during walking.
The battery operated stimulator is about the size of a pack of cards and can be worn at the waist, on the belt or in a pocket. It is activated by a pressure sensitive switch placed in the shoe and provides electrical impulses to the nerves through electrodes stuck to the skin on the lower leg just below the knee. As the foot lifts and releases pressure on the switch, the stimulation causes the foot to tilt to the correct angle as the leg swings through. When the foot is placed on the ground again pressure is reapplied to the switch and the stimulation ceases.
Electrical stimulation to correct dropped foot produces a more normal walking pattern and therefore reduces the need for compensatory strategies. It can enable people to walk faster, further and with less effort. More generally the improvement in walking pattern reduces the risk of falls and leads people to become more confident and independent in their walking.
In some cases the walking pattern without stimulation can be improved sufficiently for people not to need to continue with stimulation treatment. This has not been found to be the case so much in those with MS owing to the progressive nature of the condition.
Who may benefit from using FES?
Those people who have difficulty walking as a result of a stroke, MS, an incomplete spinal cord injury or head injury. It is very important that the nerve fibres between the spinal cord and the muscles they supply are not damaged, as the impulses need to travel along the nerves uninterrupted.
Are there any risks or side effects?
Electrical stimulation causes a tingling 'pins and needles' sensation on the skin. Although most people do not find it uncomfortable, a few do and for this reason do not use it. This is particularly true of people with MS who are often quite sensitive to changes in sensory input. However, a short period of stimulation at a low intensity usually overcomes this problem.
Sometimes, even though people are carefully assessed, treatment with electrical stimulation does not benefit them or they find it difficult to use the stimulator effectively. Very occasionally people find that the stimulation or the electrodes cause irritation of the skin. This can usually be addressed by using hypoallergenic electrodes or changing the type of stimulation used.
FES research
Electrical stimulation was first used to correct dropped foot in 1961 when Liberson reported that it significantly improved the walking of people who had had a stroke. It was not until 1977 that its use in MS was reported, showing increased muscle strength and reduction in tightness in the calf muscle. A questionnaire survey of users, which included people with MS, found that the device was well accepted although there were problems with electrode placement and use of the stimulator away from the clinic.
p>The Department of Medical Physics and Biomedical Engineering at Salisbury District Hospital set up the first clinical service for FES in the UK in 1996 following the results of a research trial to prove its efficacy in improving walking in stroke patients. FES is now a recommended NHS treatment for patients following stroke.An evaluation of the clinical database at Salisbury District Hospital demonstrated improvements in both walking speed and effort in people with MS who have used FES. Responses to a questionnaire indicated reduced effort of walking as their main reason for using FES, as well as increased confidence in their mobility, reduced tripping and falling and the ability to walk further.
The first study investigating the effect of FES on walking and quality of life in people with MS, funded by the MS Trust, has recently been completed in Salisbury. The results are being analysed and should be published later this year. It is hoped that this work will provide clinical evidence for the use of FES to aid walking in people with MS, so that it can be used appropriately as an adjunct to other physiotherapy treatment.
How do people get FES treatment?
People who are interested in receiving FES treatment in Salisbury need to be referred by a doctor, either their GP or a consultant, to Professor Ian Swain in the Department of Medical Physics and Biomedical Engineering at Salisbury District Hospital, Salisbury, Wiltshire SP2 8BJ. The team at Salisbury is able to tell you whether there is treatment available in your area and a similar doctor's referral would still be required for treatment from your local service.
The department has now treated almost 2000 people with just over 500 of these having MS. There are increasing numbers of people with MS being referred to the FES service from all over the UK as awareness of the treatment grows.
Over the past few years the department has provided training courses for clinicians interested both in the application of FES and in setting up a clinical service in their locality. More than 800 clinicians have been trained and there are around 80 places in the UK and abroad where treatment is available and whose equipment is provided by Salisbury.
Funding for treatment will depend on the way each area allocates its budget and therefore will be agreed locally. Sometimes people are able to obtain funding on an individual basis from an MS charity locally. Some small local FES services have received help from the local hospital League of Friends, who may purchase equipment for a service to use rather than fund an individual's treatment.
The provision of a local service can be much more cost effective than that at Salisbury and of course people have far less distance to travel. If enough people are interested in having FES as part of their local service it is important to contact both your GP and the physiotherapy service at the local hospital or MS therapy centre, if there is one in the area, to see if they offer FES as part of their overall treatment package or would be willing to do so. If you would like to find out more about FES, Salisbury has an information-packed website at www.salisburyfes.com or email enquiries@salisburyfes.com
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Open Door articles are reproduced as published. They are not updated to take account of subsequent developments. Use appropriate caution in acting on the information in any article.