Transcutaneous electrical nerve stimulation
TENS is the name for electrical stimulation produced by a portable stimulator and used to treat pain. Electrode pads with wires attached are stuck to the surface of the skin over the area of pain. Nonpainful electrical stimulation is delivered, usually via a small portable battery-powered device.
This masks the pain by producing a tingling sensation. There is also some evidence that the stimulation, if applied for an appropriate duration, can help release the body's own natural pain-controlling chemicals (neurotransmitters).