TENS, ES, FES, EMG triggered NMES
What is the difference?
EMG triggered NMES, ES or TENS for Stroke Rehabilitation?
Are there differences between the above listed technologies? Yes, there are, and there are vendors who offer ineffective devices to stroke survivors. Sometimes, these vendors base their claims on published clinical studies performed with EMG triggered NeuroMuscular Electrical Stimulators (EMG-triggered NMES) or Electrical Stimulators (ES).
Electrical Stimulators (ES)
After Stroke many patients experience muscle dysfunction. Rehabilitation often includes Electrical Stimulation to improve muscle performance. Since it is important to prevent muscle disuse ES will maintain mobility in the hope that the patient will regain spontaneously (some) muscle control. In case spasticity occurs (involuntary muscle contraction) ES may reduce the unwanted muscle contractions to obtain pain reduction (e.g. shoulder dislocation). Motion of joints may be lost (joint contracture) e.g. opening of hand, straightening of elbow or difficulty with shoulder movements.
Use of ES includes early intervention and prevention of loss of motion. Benefit of ES in reduction of spasticity requires use for 1-2 hours per day over at least 1-3 months. If ES is discontinued spasticity is expected to return, requiring lifelong use.
Properly working ES devices generate electrical stimulation impulses, which meet the specific requirements to obtain the optimal required muscle movements, like pulse form, pulse width, pulse repetition rate, stimulation frequency, stimulation current etc. etc.
When ES is used in combination with a prosthetic application it is called Functional Electrical Stimulation (FES). Medications to paralyze muscles will reduce spasticity but result in weaker or completely paralyzed muscles.
Transcutaneous Electrical Nerve Stimulators (TENS)
TENS devices have been designed for pain reduction and nothing more! TENS decreases pain perception and may be used to control acute and chronic pain. Transcutaneous (through the skin) electrical nerve stimulation sends mild electrical pulses to specific nerves. The current generated might relieve stiffness, improve mobility, and relieve pain. The treatment is believed to stimulate the body's production of natural painkillers (endorphins). TENS devices are especially designed in such a way that they will not generate electrical currents causing muscle contractions and if they do, they might be even dangerous!
WE BELIEVE THAT All TENS devices are inherently unsuitable
for any form of Stroke Rehab.
EMG triggered NeuroMuscular Electrical Stimulators
EMG triggered NMES is a technology to detect the extremely small electrical ElectroMyoGraphic (EMG) signals still measurable in paralyzed muscles after stroke and use these signals to initiate electrical stimulation impulses to the same muscles resulting in actual muscle movement. This form of stroke rehab is used to re-learn and re-develop spontaneous muscle control, which cannot be done by Electrical Stimulation alone.
Muscle movement is caused by electrical impulses originating in the brain, which are transmitted via nerve cells to the muscles. When a person wishes to initiate muscle movement the brain sends electrical signals to the muscles. Upon arrival of these signals, the muscles respond by contracting. These electrical signals can be measured over muscles and they are called electromyographic signals.
When brain damage is caused by a stroke, regular electrical impulses are not generated or can no longer reach muscles, normal muscle contraction becomes impossible. Although there are always minuscule EMG signals, these are mostly extremely small and unable to control the muscles. This often leads to irreversible damage and loss of muscle function, resulting in muscle paralysis such as “claw” hand or “drop foot”.
After a stroke, the patient is rehabilitated by physical therapy. This is done in the hope that there will be some form of spontaneous recovery and that the muscles will not become too stiff. In most cases however, recovery will not occur and the patient will be left with severe disuse muscle atrophy and paralyzed muscles, greatly affecting the quality of life.
Devastating paralysis of muscles can often be prevented if the patient is offered the possibility to re-learn the use of the affected muscles by improving electrical muscle activity. An excellent approach to re-educate muscles to achieve voluntary muscle contractions is to combine EMG measurement and NMES muscle stimulation technologies as in the Biomove system. In almost all cases, there is still a very small amount of electricity (EMG), which reaches the muscles. These small EMG signals are picked up by “stick on” electrodes placed over the paralyzed muscles. The Biomove device then amplifies these small signals and when an internal preset “trigger” level is reached, the built-in electro stimulator returns an electrical stimulation impulse (NMES) to the same muscles. These muscles now respond as originally “instructed” by the patient's own brain signal. In this manner the patient is able to obtain direct muscle movement, assisted by the Biomove device.
The patient uses this method of cognitive re-learning to rehabilitate the muscles of the otherwise paralyzed hand or foot. Training at home with the Biomove EMG triggered NMES device, may help achieve voluntary muscle contractions of the paralyzed muscles. Read more about this technology on the website www.biomove.com
Note: All the above devices are regulated by the FDA in the USA and may only be sold with a prescription from a Medical Doctor. There are companies selling uncertified (possibly dangerous!) devices through so-called “medical” websites on the Internet. You may report them to the FDA http://www.fda.gov/oc/buyonline/buyonlineform.htm to protect yourself and your fellow citizens.