Transcutaneous
electrical nerve stimulation (TENS) is the administration of an electrical
stimulus to the skin. The theory of TENS states the following: When a
non-painful stimulus is applied, it literally inhibits the perception of pain
by closing the gate and blocking the transmission of a painful stimulus at spinal
cord levels. The simplest and most physiologic demonstration of this is
"when you rub, it hurts less." It is almost instinctively
recognized that, very often rubbing a painful area decreases the pain.
The application of an electrical stimulus on the surface of the skin produces a
similar result.
The stimulator is a battery-operated unit about the size
of a pack of cigarettes, which can be worn clipped to a belt or inconspicuously
inside the clothes. It attaches by means of lead wires to either 2 or 4
electrodes and is taped to the skin. The patient adjusts the voltage so
that sensation is perceptible but not painful. The stimulator can be used
constantly or intermittently, depending on the response of the patient.
The electrodes may be applied initially to the area of pain or across the area
of pain.