Why is Electrical Stimulation Used?
Information on how NMES benefits movement and function:
Why is electrical stimulation used for those with cerebral palsy and other movement disorders? How does it help? What is task-specific NMES?
Task-specific neuromuscular electrical stimulation (NMES) is the use of electrical stimulation (ES) according to the task or the activity that the child is doing. NMES is similar to exercise and when it stimulates the muscle that is needed for the task at the time it is needed, the approach is called task-specific NMES. A hand held remote switch is used to turn on the stimulation when the muscles are needed and off when the muscles are not typically used. Thus the child learns to use the muscle when it is needed and to not use it when it is not needed. Functional electrical stimulation (FES) is a subheading for NMES but the acronym has come be to used interchangeable with NMES as both FES and NMES have functional improvement as goals.
Without NMES/FES this two-year old child with spastic diplegia ignores his right arm and hand. The parents stated that he never used the right hand. In the first two photos he is standing and playing with the left arm while the right arm is to the side or behind him not participating in any activity.
With NMES for the first time to the hand and fingers, the child willingly and spontaneously used his right hand. In the photos below he immediately brought the arm in front of him when he felt the NMES.
Within a minute, the time needed to find an activity that he wanted to do, he opened his hand. A small ball was given to him to put into a ball run. He reached out with the previously unused hand, took and ball and put it into the ball run. I was surprised that he was also able to let go of the ball so that the activity was totally successful and he was interested to practice it again and again. ES gave both a sensory and a motor input to the child so he was aware of his arm and hand and used it.
The four photos below show a twenty year old woman with spastic quadriplegia. Below left, she is using her more involved hand on Nintendo’s Wii controller. She has difficulty maintaining grasp and pointing it at the screen. Below right, NMES stimulates many muscles to allow the young women to use the controller and point it at the screen during a Ping-Pong game. Below lower left, after NMES was used, she had enough carry over to hold two controllers. The much improved wrist alignment is clearly shown although NMES is no longer being used. Below lower right, NMES gives enough sensory-motor input to the hand to give her enough awareness so that she can use the thumb to press the button on the controller to control the Wii.
The photo to the left shows a four-year-old girl who had never held an object long enough in the left hand to put it in her mouth. She does put her hand in the mouth but had never put a rattle or other item there. Here she is shown in supported sitting. When NMES was used on the left hand, within a few seconds she was able to maintain grasp and put the pompom in her mouth and hold it there for at least a minute.
Below are four photos of a child with spastic diplegia who was beginning to develop a scoliosis. He is in a standing and playing at a table. The first photo was taken before ES was used. His back is not straight. When two electrodes were used on the back with task-specific NMES/FES to muscles that were not working correctly, the back became straighter. A second pair of electrodes was used to stimulate more muscles (third photo) and the back became straight. The last picture shows how the child benefited from task-specific NMES as the child’s back is straight without NMS after six months NMES was first used for the back.
Because the child is awake and aware of the stimulation, actively participating in a task and not asleep or lying down, carry over can and did occur. Movement science has shown that for there to be carryover from exercise or practice of an activity it needs to have be task-specific.
The next child, above, is four years old, also benefited from NMES to the trunk. The child had selective dorsal rhizotomy (SDR) and was also developing a scoliosis which has been found to be common following such surgery. His back had deteriorated so much since the SDR that he was scheduled for back surgery to place metal rods in back bones, vertebra, to correct the scoliosis. However, NMES was able to straighten the spine immediately when first used abd the surgery was canceled. After 4 years the spine was still straight and he continued with his home NMES program. Surgery was not rescheduled as the progress was good.
NMES is also very helpful for leg and hip muscles. When it is used on the calf muscles for children who walk on their toes, they often become immediately able to walk with the foot flat on the floor. Electrical stimulation usually is given with a small portable stimulator. When it is given while the child walks a remote switch must be used to help the muscle contract at the typical timing. This will help motor function and motor learning so that the child can progress to a time when he or she can walk well without NMES. Below are photos of a child aged two years who has spastic diplegia before NMES was used. She is a toe walker.
When NMES was put to the calf muscles and operated according to the activity she stood and walked with the feet flat on the floor.
The photo to the left shows the electrodes on the calves as she is standing. The series of photos below show her walking flat footed as NMES stimulates the muscles with a hand held remote switch to control the typical timing for the muscle.
Many therapists and physicians are afraid to stimulate the calf muscles because they fear the calf is too strong. However, research has shown that these muscles are weak and need to be strengthened. NMES to the calf has been shown to be very beneficial. My articles as well as one by Comeaux who studied my approach are listed in the bibliography on this web site.
The photos above show immediate changes in posture when NMES was put to the calf muscles and other muscles of a child age seven with spastic diplegia. He walked with a walker and was at GMFCS Level III. He progressed with task-specific NMES during PT to be able to walk independently without a walker. At age nine years he moved from GMFCS Level III to GMFCS Level II which is considered to be unexpected.
Above are the photographs of a child age seven months with severe mixed quadriplegic cerebral palsy. He is held in standing. He was scheduled for surgery to correct the foot position. The second photo was taken seven months later when he was 14 months of age after NMES had been used for seven months to various muscles. The surgery was canceled.
The above two photographs below are of a child who was eighteen months of age. In the first photograph the therapist is trying to bend his knee. He is standing at a table and trying to reach a toy. The therapist is having a difficult time as the child is so strongly straightening his knee. The next photographs show him standing easily at the table as his mother just supports his back. He is flexing one leg where NMES is stimulating the gastrocnemius, a calf muscle. The knees alternately bend as NMES stimulates one leg and then the other. The child is standing more relaxed and able to bring the left arm forward to play. Without NMES the left arm had been held stiffly near his body, perhaps to help him stay upright as the calf muscles were not supporting him until NMES was used.
NMES used in a task-specific way is an excellent adjunct to a child’s physical therapy. Immediate and long term effects are seen. It is important for a child to increase his muscle strength and development as he grows in order to improve his functional skills.
Several myths exist concerning electrical stimulation that result in various therapeutic approaches. One myth is that children do not tolerate ES and so the child needs to be sleeping with amplitude so low that the child does not feel it. One may wonder what good that does as the child has no awareness of the muscle stimulus and is not able to learn from it so that there is no carry-over into the goal.
Others who are afraid the child will not tolerate ES of any type surgically implant the electrodes so that the stimulation is not felt and the amplitude may be very high. However, sensation is especially important in movement. Children do tolerate the stimulation when the parameters and approach are correctly given.
Another myth is that NMES will not help toe walkers so that surgery needs to be done first. This is very unfortunate and it is unknown as to why the myth prevails after many articles have been published that show the opposite. The literature has shown that the calf muscles are weak and often weaker than the anterior tibialis muscle on the front of the leg bends the ankle. Toe walkers are often immediately helped if NMES is done with the appropriate parameters to the calf muscles. Many of these myth believers have been too afraid to even try NMES to the calf themselves to see the results and thus just perpetuate the myth. Positive results of NMES to the calf have been seen immediately and over time (Carmick and Comeaux in the Publications link). It is worth trying as there will be no ill effects. NMES is similar to exercise and when one stops exercising the effects may go away if the muscles are not used. We all know what happens to our body when we become couch potatoes. One can see if it works or not. It is just important to have appropriate settings (parameters) for the NMES unit, the correct muscle and the appropriate timing.