Functional electrical stimulation (FES) factsheet
Date of issue: March 2007
Reviewed: June 2008
What is functional electrical stimulation?
FES is a form of treatment to aid mobility in a number of conditions. It was first used in 1961 to correct dropped foot in people who had had a stroke and has been used with people with MS since 1977. In MS, damage to the nerves in the central nervous system prevents or interrupts messages passing to or from the brain via the spinal cord. One of the problems this poor transmission of messages can cause is dropped foot. Dropped foot is the inability to lift the foot and toes when swinging the leg forward during walking. This causes the toes to catch or the foot to drag on the ground, which can lead to falls and a loss of confidence.
Some people will compensate for the effects of dropped foot by altering the way that they walk. In time this can lead to further problems such as pain in the hips or lower back, a tightening of muscles and poor balance.
FES compensates for the interrupted messages from the brain by applying an external stimulus to nerves. Self-adhesive electrodes are placed on the leg and connected to a small stimulator, which is about the size of a pack of cards and can be worn on the belt or carried in a pocket. Small electrical impulses are used to excite the nerves that supply affected muscles producing basic but useful movement.
The impulse is activated by a pressure sensitive switch in the shoe, causing the foot to tilt to the correct angle when lifted. When the foot is placed on the ground again, pressure is reapplied to the switch and the stimulation ceases.
Who may benefit from FES?
As FES applies stimulation along the existing nerves, the nerve fibres between the spinal cord and the muscles they supply must be undamaged. In practice this means that the individual needs to be able to walk, even if only a few metres with a stick or crutch.
Electrical stimulation to correct dropped foot produces a more normal walking pattern. It can enable people to walk faster, further and with less effort. It also reduces the risk of falls and leads people to become more confident and independent in their walking.
As FES allows renewed movements in weakened muscles, it is used to complement physiotherapy exercises and to allow people to build up strength and range of movement.
Although FES can be used to make the most of a person's abilities, it does not protect the nerve pathways from further deterioration. For some people this will mean that there will come a point when FES is no longer effective.
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 this a problem, some people with MS are quite sensitive to changes in sensory input and find the effect uncomfortable. 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
In reply to a questionnaire FES users at the National FES Centre at Salisbury District Hospital indicated reduced effort of walking as their main reason for using the treatment, which can also be used to treat problems with other muscle groups, for instance in the arms. People found FES increased confidence in their mobility, reduced tripping and falling and the ability to walk further.[1]
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 further study is therefore now addressing this question. The results have been submitted for publication in a peer reviewed journal.[2]
The second study is looking at quality of movement as well as speed and effort of walking. This study is also comparing the combination of FES and physiotherapy with the effects of either treatment in isolation.
How do people get FES treatment?
The use of FES is growing, with an increasing number of centres offering the treatment. An assessment by a physiotherapist trained in the use of FES is required to ensure that the treatment will be suitable for the individual. The physiotherapist will also make sure that the pads are placed properly and that the equipment is being used most effectively.
Odstock Medical Limited, the NHS company that was formed by the department of Salisbury District Hospital that developed the treatment, has a map of UK centres on their website at www.odstockmedical.com.
Alternatively, write to
Odstock Medical Limited
The National Clinical FES Centre
Salisbury District Hospital
Salisbury
SP2 8BJ
phone: 01722 429065
email: enquiries@odstockmedical.com
References
- Taylor PN, Burridge JH, Dunkerley AL, et al.
Clinical use of the Odstock dropped foot stimulator: its effect on the speed and effort of walking.
Archives of Physical Medicine & Rehabilitation 1999;80(12):1577-1583.
abstract - Mann GE, Jolley CL, Esnouf JE, Taylor PN.
A randomised trial to investigate the effect of functional electrical stimulation on mobility and quality of life in patients with multiple sclerosis.
Awaiting publication.