Transcutaneous Electrical Nerve Stimulation

Transcutaneous electrical nerve stimulation, abbreviated TENS, is a device that produces a mild electric current to stimulate nerves for therapeutic purposes. TENS by definition covers the complete range of transcutaneously applied currents used for nerve excitation, though the term is often used more narrowly for the pulses produced by portable stimulators used to reduce pain. The unit is usually connected to the skin with two or more electrodes, typically conductive gel pads, and a battery-operated TENS unit can modulate pulse width, frequency and intensity; it is generally applied at high frequency with an intensity below the threshold for motor contraction, or at low frequency with an intensity that does produce motor contraction, and many units now use a mixed-frequency mode to reduce tolerance from repeated use. While TENS has proved effective in clinical studies, there is controversy over which conditions it should be used to treat.