TENS units are pocket-sized devices used as an alternative treatment for pain symptoms. The units produce a small electrical shock administered through two or more electrode pads that are applied on the skin. Self-administered use of TENS requires a certain degree of knowledge on where to place the electrodes on the body.
Electrode Nerve Stimulation
TENS is an acronym for transcutaneous electrical nerve stimulation. Transcutaneous electrical nerve stimulation involves the use of electrical currents to stimulate nerve function, according to the Pain Clinic, a pain treatment resource site. These mild currents are designed to stop the nerves from conducting pain messages to the brain and stimulate the release of endorphins, the body's natural painkillers. The TENS unit is made up of a pocket-sized controller module connected to two or more wire electrodes. Units can emit high-frequency currents between the range of 80 to 100 hertz, or low-frequency currents of 2 to 4 hertz. High-frequency currents work to stop pain messages, while low-frequency currents stimulate endorphin secretions.
Proper electrode placement is especially important when using TENS units, according to Drugs.com. The right nerve must be targeted, and the electrodes must be aligned with how the nerve connects with the spinal cord. Units that include two electrodes are designed to target the local region where pain sensations originate. Units with four electrodes can target the local region, as well as its corresponding point along the spinal column. Do-it-yourself electrode pad placement involves locating the dermatome associated with a particular pain region and situating the electrodes accordingly. A dermatome is an area of skin that's stimulated by a single spinal nerve. In total, there are eight cervical nerves along the upper spine, 12 thoracic nerves along the middle region of the spine, five lumbar nerves along the lower spine, and five sacral nerves along the tailbone area of the spine. The area of pain being treated will determine proper electrode placement.
Electrode-pad placement is intended to surround the nerve that corresponds to the area where pain is felt on the body. Free charts illustrating dermatome pathways in the body can easily be found online (a basic chart is linked in the Resource section). Someone experiencing pain in the knee can place the electrodes on both sides of the area when using a two electrode unit, or the individual can place one pad directly on the pain area and the other on the region of the spine that corresponds with it. Units that come with four electrode pads offer more variation in terms of placement. For knee pain, two pads can be placed above the area, with the other two placed below the area. Or two pads can be placed on either side of the pain area, and the other two placed along the region of the spine that corresponds with the knee.