What is a TENS Unit and How Does it Work?

What is a TENS Unit and How Does it Work?

The TENS (Transcutaneous Electrical Nerve Stimulation) unit is a device that delivers mild electrical signals through the skin in order to alleviate pain. It is mainly used to relief pain due to gout, sciatica, surgical procedures, etc.
HealthHearty Staff
Electrical Signals for Pain Relief
Ancient Roman reports by Scribonius Largus state that: pain can be relieved by standing on live electric rays.
When it comes to diseases like arthritis, gout, sciatica, as well as in post-operative patients, and women in labor, pain management poses a significant challenge. Methods employed for pain relief include analgesics like non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen, antidepressants, opoids, etc., as well as therapeutic exercises and electropathy.

Electropathy involves the use of electrical signals as a part of medical treatment. This is generally achieved through the use of electrical devices designed to deliver electrical impulses at appropriate rates. A TENS (Transcutaneous Electrical Nerve Stimulation) unit is one such device designed to stimulate the nerves, and provide relief from pain. It is a battery-operated, portable, and patient-wearable device.

Given below is a brief description of the TENS unit, followed by its working mechanism.
What is a TENS Unit?
What is a TENS Unit
The fact that electrical stimulation helps to control pain has been known since ages. But it was only in the 1970s that a wearable device capable of delivering low-risk electrical signals was invented. This machine is known as the Transcutaneous Electrical Nerve Stimulation (TENS) unit. It can send electrical signals across the skin and stimulate the nerve fibers such that the sensation of pain gets blocked.

A TENS unit has three major components:

  • Electrode pads: Adhesive pads that can be attached onto the skin near, or over the painful region.
  • Leads: Wires that conduct electrical signals from the stimulator device to the electrodes.
  • Stimulator device: The battery-operated device that generates and delivers electrical signals at a set intensity.
How does a TENS Unit Work?
The stimulator of the TENS device generates electrical signals which are conducted by the leads and transferred through the skin by electrode pads. Depending on the underlying condition, severity of pain, as well as any other specific requirements, the intensity and frequency of the signals can be set using controls on the stimulator device. Two basic types of electrical signals generated through a TENS unit help to limit the sensation of pain. These are:
1) Low-intensity, High-frequency Impulses
The sensation of pain normally arises due to a set of electrical impulses generated by the pain receptors present in skin as well as visceral organs. These impulses are transmitted to the brain by nerve fibers connected to the pain receptors. When these impulses reach the brain, the individual experiences pain.

While using a TENS unit, low-intensity electrical impulses are delivered repetitively. These travel faster than the natural pain impulses of the body. As a result, the impulses from the TENS unit override the pain impulses, and reach the brain faster. The brain can process only a limited number of impulses. So the artificial impulses that reach first are processed and the lagging pain impulses which reach the brain later are not. Thus, the sensation of pain is blocked.
2) High-intensity, Low-frequency Impulses
The human body has a natural pain-relief mechanism that operates through the release of endorphins or endogenous opoids in response to stress, injury, or any other pain stimuli. These endorphins are responsible for the feeling of general well-being. The delivery of high-intensity electrical signals through a TENS unit is said to trigger the release of endorphins, and thus alleviating the sensation of pain.

A TENS unit is generally recommended for post-operative patients, pain relief during menstruation, neck pain, joint pain in individuals suffering from gout and arthritis, etc. Its effectiveness in relieving labor pain and lower back pain is debated, and considered to serve as a placebo. A TENS unit must be used by individuals with implanted devices like pacemakers and defibrillators, as well as during pregnancy, only after consulting the doctor. For others too, it is always advisable to consult the appropriate medical expert before resorting to the use of a TENS unit or any other methods of pain management.
Disclaimer: This article is for informative purposes only, and should not be used as a substitute for professional medical advice.