Transcutaneous electrical nerve stimulation (TENS) is a non-invasive technique in which a low-voltage electrical current is delivered through wires from a small power unit to electrodes located on the skin. Electrodes are temporarily attached with paste in various patterns, depending on the specific condition and treatment goals. TENS is often used to treat pain, as an alternative or addition to pain medications. Therapy sessions may last from minutes to hours.
TENS devices can be set in a wide range of frequencies and intensities, depending on patient preferences, desired sensations, and treatment goals. "Conventional TENS" involves the delivery of high or low frequency electrical current to affected areas. In "acupuncture-like TENS," lower frequencies are used at specific "acupuncture points" or trigger points. TENS may also be applied to locations on the ear ("auricular points"). Epidural stimulation and percutaneous electrical nerve stimulation (PENS), which are not included in this review, are invasive procedures that require penetration of the skin, implantation, or minor surgery.
The practice of using electricity for pain control can be traced to 2500 BC and the Egyptian Fifth Dynasty, in which stone carvings depict an electric fish being used to treat pain. During the Socratic era, electrogenic torpedo fish (Scribonius longus) were used to treat arthritis and headache. In the Middle Ages, electrostatic generators were used, and the discovery of the electric battery in the 19th century led to further experimentation.
The use of electrical stimuli for pain relief was popularized in the 19th century and became widespread in the 1960s and 1970s using battery power.
Related techniques: Acupuncture-like TENS, auricular TENS, CODETRON, electronic muscle stimulators, electroanalgesia, peripheral nerve stimulation, sensory afferent stimulation (SAS), TES (transcutaneous electrical stimulation), TNS (transcutaneous nerve stimulation), TNS (transcutaneous neural stimulation), TENMS, transcutaneous electrical analgesia.
Not included in this review: Cerebral TENS, cranial TENS, deep brain stimulation (DBS), epidural stimulation, percutaneous electrical stimulation (PENS), spinal cord stimulation (SCS), subcutaneous nerve stimulation (SCNS), or use of electrical stimulation for muscle toning.