Functional Electrical Stimulation In Multiple Sclerosis
The below article is a very good summary article written by J. M. Campbell, Ph.D, P.T. explaining some of the electrical stimulation results for multiple sclerosis patients.
For clarity purposes the term "ES" or "Estim" is a generic declaration of an external device in most cases, that produces a flow of electrons from one electrode to the other of the same channel. The flow of the electrons produces an ionic reaction in the body in the areas between the electrodes, in most cases motor nerves and muscle tissue. The most common use of a specific form of ES with multiple sclerosis patients is the term "Functional Electrical Stimulation", or FES. This is a form of estim where one stimulates motor nerves, at the same time as attempting to move mentally. The breaching of the gap between movement and the brain's message to move is preserved or restored. The FES process is accomplished with voluntary repeated movement assisted by functional stimulation.
A quicker method of accomplishing functional electrical stimulation would be to use "medium frequency Infrex interferential stimulation" with volitional movement at the same time. Typical FES applications involve multiple daily sessions ( 5 - 15), for 10 - 20 minutes whereas "functional stimulation" protocols are 1- 2x daily for 15 minutes at maximum output. Functional stimulation is designed to also increase muscle bulk and strength.
The reference to "healing decubitus ulcers" ( bed sores ) is generally a form of estim known as "pulsed galvanic stimulation", or "high voltage".
The "reduce spasticity" can be accomplished by using FES to fatigue the muscle(s) however most studies fail to then continue to use estim for extended time periods to avoid future spasticity. This accomplished by "interferential therapy" over night for 6 - 12 hours either sensory or subsensory. The process of constant, low amperage stimulation of muscles stops spasticity. Spasticity should be prevented, not treated.
Because multiple sclerosis is a chronic disorder in which there may be intermittent periods of recovery or remission, the indications for and the application of electrical stimulation [ES] will
vary with the symptoms and functional limitations. ES may be helpful in the management of spasticity, pain, respiratory dysfunction and urinary incontinence with resulting improvements in
muscle strength, coordination, balance, walking ability and performance in daily activities.
Applications that involve the use of skin electrodes may be accomplished with a variety of commercially available electrical stimulation devices that are small, battery powered and
inexpensive. Implantable electrical stimulation technology would be selected by the surgeon.
Management Of Spasticity:
ES has been demonstrated to reduce or eliminate interfering spasticity, or involuntary muscle activity, in multiple sclerosis. The involuntary muscle activity may take the form of
spontaneous muscle contractions or it may occur when voluntary movement is initiated. A variety of ES protocols have been employed. Some investigators and clinicians have used inexpensive
portable stimulators and skin electrodes [placed on the spastic muscles, or over the muscles that work against the spastic muscles or on areas of skin that receive the same nerve supply as the
spastic muscles]. The intensity of ES may be minimal, with only a tingling sensation felt by the user. In other protocols, the intensity of ES is increased to assist with joint movement. The
intensity of ES should never cause discomfort. Other clinicians have surgically placed microelectrodes over the dorsal columns of the spinal cord. Stimulation protocols varied from one
to two hours each day to intermittent use all day long, as needed. As a result of ES, spasticity has been reduced, pain was less, bowel and bladder function
improved and walking was more normal [with longer step lengths and greater walking velocity].
Maintaining Or Improving Joint Range Of Motion:
ES of muscle[s] can be used to move the joint to the end of the available range or it can be combined with the patient's exercise to be sure the patient is going to the end of the range and
stretching just a bit. Electrical stimulation for this purpose has advantages over vigorous manual range of motion including the use of the individual’s muscles to gain the range in a gentle manner
without traumatizing the tissues and it can be done several times during the day as part of a home program. When spasticity has contributed to the limitation of joint motion, the movement may
improve remarkably as ES helps to reduce the spasticity. Among the advantages of improved joint range of motion are greater ease of positioning and reduced risk for development of pressure sores.
For the individual who has the ability to walk, improved range will reduce the energy expenditure of standing and walking which should translate into less fatigue for the person with multiple sclerosis.
Improving Muscle “Strength” Or Performance:
When interfering spasticity is reduced or eliminated, muscles may appear to be stronger in the absence of actual change in the muscle properties. In addition, ES may improve the timing or
recruitment of muscles so that muscles exert force in a more useful and coordinated manner. Exercise home programs, with ES added to voluntary effort, can be designed to improve muscle
force production and fatigue resistance.
Improving Bladder And Bowel Control:
Electrical stimulation has been reported to improve urge incontinence, urethral and anal sphincter control and constipation. Investigators and clinicians have used exercise of the
abdominal and pelvic floor muscles in combination with ES of these muscles with skin electrodes. Some protocols have employed special electrodes made to fit in the anus or vagina. Surgical
approaches have included placement of electrodes on the spinal cord in the thoracic, or upper back; on the sacral spinal nerves [in the low back]; as well as in the pelvic floor near the pudental
nerve. The majority of patients [78 to 85%] reported improvements in their bowel and bladder function, but there is agreement that multiple sclerosis patients do need daily home ES treatments.
Reducting The Risk Of Respiratory Infection:
While most people with multiple sclerosis who can walk are not likely to have serious impairment of their respiratory muscle function, those in a wheelchair with decreased arm and
trunk activity are at risk for respiratory compromise and infection. One of the most serious problems is the reduction in coughing ability and ES may be useful in contracting the abdominal
muscles to assist in coughing and keeping the airway clean. Reduction of spasticity by ES may improve breathing and coughing by allowing more coordination of the muscles of inspiration and
Minimizing The Risk Of Pressure Sores And Treating Skin Lesions:
Among the many factors that contribute to pressure sores are spasticity, joint contractures, muscle paralysis and poorly fitting wheelchairs. ES may reduce the risk by reducing the
involuntary movements in spasticity, by improving joint range of motion, and by increasing the bulk of muscles that cushion the bony prominences and so distribute pressures more evenly over the
skin. Once a pressure sore has occurred, ES may be helpful in speeding the healing process. While most of the research in this area has been done in spinal cord injury or diabetes, the
findings are applicable to multiple sclerosis. Possible mechanisms include improving the oxygen supply to the skin and the muscle in the area of the sore, improving the rate of deposition of
connective tissue, or scar, and minimizing the infection in the wound. The chance of healing is, of course, better if the pressure sore is a partial thickness lesion, meaning that only the more
superficial layers of the skin are missing. In this case, the skin can grow from the base or bed of the dermis, similar to the way grass grows after mowing. If the sore is deep enough to go through
the skin, it must heal in from the sides and surgery is often needed. If there is infection underlying the skin and in the exposed bone, surgical intervention is required to clean the area and to graft
skin and sometimes muscle over the bony prominences. After wound closure, the mechanical integrity of the skin will not return to normal and it will be necessary to continue routine skin checks
and to use custom seating devices for pressure relief as needed.
Successful ES protocols have included daily stimulation for a total time of two or more hours. Some investigators have employed a very low intensity, direct current. Others have used a
pulsatile current and created a muscle contraction in the area of the pressure sore. Electrodes may be placed adjacent to the wound or one of the electrodes may be placed in the wound. In the
latter case, an electroconductive dressing is used as the electrode.
Improving The Mechanics And Energetics Of Walking:
ES has been discussed for the reduction of spasticity as well as improvement in joint range of motion and muscle performance. Maintenance of ankle dorsiflexion range of motion [to 10
degrees of ankle dorsiflexion] and modulation of ankle plantar flexor spasticity are critical to walking. It is necessary for the body weight to progress over the stance limb in order to take a step
with the other leg. If the ankle does not have dorsiflexion range or if the calf muscles contract at the wrong time because they are stretched as the body moves forward, the stance leg will be
pulled backward and the patient will have to use crutches and drag their entire lower extremity. These two problems prevent walking for many people with multiple sclerosis. ES can be employed
to rectify these problems and result in much more normal walking. There is evidence to show that people with multiple sclerosis who walk better with ES will
continue to use the ES device at home for many years. For the MS patient who has a relapsing and remitting course, ES is only needed when ankle spasticity and/or range is a problem. For
those individuals who have more persistent symptoms, ES may continue to be needed on an everyday basis to maintain walking ability for as long as possible, and then indefinitely to control
spasticity, joint range of motion and bladder function. Careful selection of shoes will contribute further to the benefits of ES. Many people with
multiple sclerosis have improved their walking ability by using rocker shoes, or clogs. Based upon the research assessment of the rocker shoes that have been most beneficial, there are specific
shoe dimensions [in terms of heel bevel, forefoot rocker and heel height] that result in improvement for those patients who are candidates. It is necessary to have sufficient muscle
control at the hip and knee in order to be able to walk at the increased velocity of joint motion afforded by the rocker shoes.
J.M. Campbell, Ph.D., P.T.
General Considerations in the Clinical Application of Electrical Stimulation
ES in Multiple Sclerosis
Comfort in Electrical Stimulation
ES in Pain Modulation
ES in the Modulation of Spasticity
ES in Walking
ES and Muscle Performance
ES for Improving Joint Range of Motion
ES in the Management of Bowel and Bladder Incontinence