Definition

Electrical nerve stimulation, also called transcutaneous electrical nerve stimulation (TENS), is a noninvasive, drug-free pain management technique. By sending electrical signals to underlying nerves, the battery-powered TENS device can relieve a wide range of chronic and acute pain.

  Purpose

TENS is used to relieve pain caused by a variety of chronic conditions, including:

• neck and lower back pain
• headache/migraine
• arthritis
• post-herpetic neuralgia (lingering chronic pain after an attack of shingles)
• sciatica (pain radiating from lower back, through the legs, to the foot)
• temporomandibular joint pain
• osteoarthritis
• amputation (phantom limb)
• fibromyalgia (a condition causing aching and stiffness throughout the body)

The device is also effective against short-term pain, such as:

• shingles (painful skin eruptions along the nerves)
• bursitis (inflammation of tissue surrounding a joint)
• childbirth
• post-surgical pain
• fractures
• muscle and joint pain
• sports injuries
• menstrual cramps

  Precautions

Because TENS may interfere with pacemaker function, patients with pacemakers should consult a cardiologist before using a TENS unit. Patients should also avoid electrical stimulation in the front of the neck, which can be hazardous. The safety of the device during pregnancy has not been established.

TENS doesn't cure any condition; it simply eases pain. Patients who are not sure what is causing their pain should consult a physician before using TENS.

  Description

The TENS device is a small battery-powered stimulator that produces low-intensity electrical signals through electrodes on or near a painful area, producing a tingling sensation that reduces pain. There is no dosage limitation, and the patient controls the amount of pain relief.

Some experts believe TENS works by blocking pain signals in the spinal cord, or by delivering electrical impulses to underlying nerve fibers that lessen the experience of pain. Others suspect that the electrical stimulation triggers the release of natural painkillers in the body.

Patients can rent a TENS unit before buying one, to see if it is effective against their pain.

  Preparation

After TENS has been prescribed, a doctor will refer the patient to a TENS specialist, who will explain how to use the machine. The specialist works with the patient to determine the settings and electrode placements for the best pain relief.

  Risks

TENS is nonaddictive and completely safe. The only side effect may be a slight skin irritation or redness in some people, which can be prevented by using different gels or electrodes.

Normal results

The amount of relief a person gets using TENS depends on the underlying cause of the pain, a person's mental state, and whether or not medication is also used. At least one study found that both a real TENS machine and a placebo were equally effective in reducing pain. This suggests that at least part of its effectiveness may be due to the patient's belief in its ability to ease pain.

   Key Terms:

Fibromyalgia A condition characterized by aching and stiffness, fatigue and poor sleep, as well as tenderness at various sites on the body. Osteoarthritis A painful joint disease aggravated by mechanical stress. Phantom limb The perception that a limb is present (and throbbing with pain) after it has been amputated. Post-herpetic neuralgia Lingering pain that can last for years after an attack of shingles. Sciatica Pain that radiates along the sciatic nerve, extending from the buttock down the leg to the foot. Temporomandibular joint pain (TMJ) Pain and other symptoms affecting the head, jaw, and face that are caused when the jaw joints and muscles controlling them don't work together correctly.