A Transcutaneous Electrical Nerve Stimulator, more commonly referred to as a "TENS unit" and pronounced /ˈtɛnz/ tens, is a portable electronic device that produces electrical currents used to stimulate nerves through unbroken skin. The unit is usually connected to the skin using two or more electrodes. A typical battery-operated TENS unit consists of a pulse generator, frequency and intensity controls, and a number of electrodes. Transcutaneous Electrical Nerve Stimulation is a passive, non-invasive, non-addictive modality with no known side effects. TENS works to decrease pain perception and may be used to control acute and chronic pain. It may also be used with other treatments such as exercise. A 2007 meta- analysis of studies going back many years indicates that TENS is an effective treatment for chronic musculoskeletal pain. Transcutaneous (through the skin) electrical nerve stimulation sends a painless electrical current to specific nerves. The current may be delivered intermittently. The mild electrical current generates heat that serves to relieve stiffness, improve mobility, and relieve pain. The treatment is believed to stimulate the body's production of endorphins or natural pain killers. TENS is also used to deliver topical steroid medication through the skin to treat acute episodes of pain. The mild current causes the medication to migrate into soft tissue serving to reduce inflammation.
The portable TENS stimulator is a small battery-operated device that can be worn around the waist. The unit can be turned on or off as needed for pain control. Although these units can be purchased or rented, a prescription from a physician is required. To ensure the individual will benefit from TENS, the portable device is used on a trial basis before the individual takes it home for long-term use. Unfortunately, TENS is not always an effective treatment. Persons with pacemakers should avoid TENS because the electrical current could interfere with the operation of a pacemaker.