Functional Electrical Stimulation is the technique in which electrical stimulation is used in order to obtain a desired functional movement.
It has been in use since 1960. Lieberson was the first one who used it for the treatment of foot drop. It had been used in the past for the patient suffering from chronic stroke or the gait abnormalities.
In Functional Electrical Stimulation, biphasic rectangular constant impulses are used, with variation of pulse width from 150 ms-40 ms depending upon the severity of degeneration, a single session of 60 min or twice a day with 30 min is usually enough to achieve appropriate results.
In functional electrical stimulation, multiple channel electrical stimulators are used in order to obtain a functional movement pattern. There is a microprocessor that controls the function of these electrical stimulators. The basic function of these electrical stimulators is to cause the recruitment of the muscles, which in turn are responsible for the functional pattern.
Recruitment of muscles is not a single step. In fact, a synergistic sequence is programmed and after its programming, the stimulation is used to obtain the desired therapeutic results.
Functional Electrical Stimulation Application Technique:
Electrodes are placed on the appropriate stimulation points on muscle. As these electrodes are mostly surface electrodes, so they do not make contact with the stimulation points appropriately. For this reason, multiple researches are ongoing. According to these researches, in order to obtain best results, there should be an implantation of the electrodes and stimulator in the muscles or the nerves, depending upon the results required.
Set the activation sequence on the computer control system before applying the electrodes on the patient so that the patient can easily perform the required functional pattern. For further safety of the patient, some sort of feedback from the stimulated muscles should be obtained. This can help the computer control system to correct the movement errors, if they are made. In order to achieve this goal, closed loop feedback control system is under the investigation.
There are various methods that can be used to achieve the programmed movement patterns. mostly foot switches or crutch switches are used for the activation purpose. However, some control devices are designed in such a way that they use movement of the contra lateral shoulder for activation. In addition, some verbal commands can also be used to get the activation of the system.
Functional Electrical Stimulation Clinical Uses:
- Foot drop (stroke)
- In spinal cord injured patients for obtaining flexion in swing phase.
- In upper limb, functional grasp strength can be enhanced in stroke, TBI, CF, SCI.
- It has shown good results in the case of hemiplegic shoulder to prevent subluxation.
- Functional Electrical Stimulation can be used as an adjunct in the exercise programme designed for the patient suffering from neuro muscular problems.
- It also increases the strength of the bladder in an uncontrolled bladder that has been caused by some neurological problem.
Examples of Functional Electrical Stimulation:
Some examples of Functional Electrical Stimulation use are given below:
Use of Functional Electrical Stimulation For Haemiplegic Shoulder:
In a haemiplegic patient, The sublaxation of the shoulder is decreased by use of Functional Electrical Stimulation as it increases the strength in the muscle surrounding the shoulder. The pulse duration should be 200-350 us, frequency should be 30-40 pps, ramp up time and down time both should be of 3 sec, time duration should be 30 min-6 hr, 5-7 days/week. 4-6 weeks.
Use Of Functional Electrical Stimulation For Improving Hand Or Upper Extremity Function:
Functional Electrical Stimulation causes a reduction in the spasticity and increases the strength along with an increase in the range of motion. Significant improvements in the grasp have been shown in many studies. Pulse duration should be 200-350 us, frequency should be 30-40 pps, ramp up time and down time should be kept very short for obtaining the effect. The timeduration depends upon the fatigue of the muscles.
Use Of FES For Gait Improvement:
It helps in the clearance of the foot from the ground by providing the assistance with dorsi flexion. A foot switch or remote switch has to be placed under the heel of the patient. Now as the foot moves in to swing phase, the pressure from the switch is relieved and there will be activation of the stimulation process, And when again pressure is put on to the switch, this stimulation ends.
The pulse duration should be 200-3450 us, frequency should be 30-40pps, ramp up time and down time should be kept at 0 sec. The time duration depends upon the fatigue of the muscles.
Use Of FES For Exercise:
In the spinal cord injured patients, FES can also used for exercise. The most common example of this is the use of a bicycle that is responsible for the stimulation of the muscles of lower extremity like quadriceps, glutei and hamstring muscles. This is not only helps to increase the strength butt also increases cardiovascular endurance and decreases the risk of osteoporosis.