What is TENS?
Transcutaneous Electrical Nerve Stimulation (TENS) is used to relieve pain over muscles using low voltage current. It’s a small portable device which passes low voltage current through electrodes. Electrodes are placed on the skin over the pain spots to stimulate the nerves.
Figure 1 TENS device with Pads
How does TENS work?
In simple words, TENS just blocks the pain signal from muscles reaching the brain. It acts as barricade; the effect is temporary. There are two theories behind the pain control
(i) Gate Control Theory, which suggests that by electrically stimulating sensory nerve receptors, the gate mechanism is closed in the segment of the spinal cord, preventing pain-carrying messages from reaching the brain and locking the perception of pain.
(ii) The Endorphin Release Theory, which suggests that electrical impulses stimulate the production of endorphin and encephalin in the body. These natural, morphine–like substances lock pain messages from reaching the brain, in a similar fashion to conventional drug therapy.
Figure 2 Working Principle
What is TENS used for?
TENS is not a cure but it can be used to relieve your pain temporarily up to 24 hours but it varies from case to case.
TENS unit can be used to treat the following symptoms:
Neck and back pain
Painful diabetic neuropathy
Spinal cord injury
How to use TENS?
Attach the pads/electrodes in appropriate location (Refer Figure 3 for placement) and turn on the TENS device. You will feel a slight tingling sensation passing through your skin.
The machine has a dial that allows you to control the strength of the electrical impulses.
Start with a low impulse setting and gradually increase it until the sensation turns strong but comfortable. If the tingling sensation begin to turn painful or uncomfortable, reduce it slightly.
Switch off the TENS device to stop the treatment and remove the electrodes from your skin.
Figure 3 Placement of TENS electrodes
Who shouldn’t use TENS? Are there any side effects?
TENS should not be used without your doctor’s advice. It is not safe for everyone to use. Some might be allergic to pads causing itches or irritation on the skin.
TENS should not be used on a person who has any heart disease.
Patients with pacemaker or any metal implanted on their body should not use it.
For an epilepsy patient, electrodes should not be placed on head, neck or shoulders.
Do not use TENS if you have history of cancer in the last 5 years.
Person with bleeding disorder should not use TENS, as it may increase the risk of bleeding in the person.
Handbook of Biomedical Instrumentation ; R.S.Khandpur