"TENS" is the short form for Transcutaneous Electrical Nerve Stimulation. The "TENS unit” is a miniature pocket size, portable, battery-operated device that transmits electrical impulses to certain parts of the body and block pain signals. Transcutaneous electrical nerve stimulation (TENS) is a drug-free method of pain management. The device generates mild currents which inhibit the transmission of pain impulses from the skin to the brain. This form of electrical energy has been used in treating pain associated with numerous conditions.

TENS units should only be used under the supervision of a doctor or physical therapist. Electrodes are attached to the surface of the skin area where one is experiencing pain. Once the technique has been learnt, TENS can be used as an outpatient. It is important to learn how to:

• Properly place the electrodes
• Operate the device
• Change the batteries
• Adjust the setting
• Make sure the device is working properly

Numerous conditions can be treated with TENS and include:

• Pelvic pain
• Neuropathy
• Rheumatoid and osteoarthritis
• Lower back pain
• Joint and neck pain
• Muscle pain, fibromyalgia
• Post operative pain

In addition, TENS has been used to stimulate nerves in patients with strokes, spasticity and in those who are paralyzed. TENS has also been advocated as a treatment for pressure sores, non healing ulcers and lymphedema in the extremities.

The actual mode of action of TENs is not understood but is thought to act by blocking the painful nerve impulses from reaching the spinal cord. When TENS unit is used appropriately, the stimulus it provides inhibits pain transmission to the brain. However, when the intensity of the TENS stimulation is too strong it can infact augment the pain.

There are some individuals who show a positive response to pain relief whereas there are others who have no pain relief from TENS. In some cases, relief of pain is only obtained when TENS is combined with drugs to decrease pain. It is not known who will and who won’t respond to TENS.

Some people have immediate relief of pain whereas other may respond after 4-8 weeks. For some chronic pain patients, a TENS unit provides pain relief that can last for several hours.

TENS may be used in outpatient settings such as rehabilitation centers, physical therapy and healthcare clinics. It is usually applied by a physician, physical therapist, chiropractor, osteopath or an occupational therapist.

Patients who respond to TENS in therapy can be trained to use it at home. Patients may rent or buy the device. The price varies widely, but the unit usually costs several hundred dollars. A physician prescription is required to obtain a TENS device. Some insurance companies do pay for the device.

A typical TENS unit can be carried in a small pocket just like a cell phone. The device consists of a power module, or can be powered by a battery. The wires are attached to the person with adhesive pads/electrodes. The electrodes are placed on the skin and the current is transmitted to the nerves below.

The length of a session can vary widely but typically is 45 minutes. Maximum benefits seem to be related to frequency of use. TENS can be used several times a day. In those individuals in whom it works, TENS can not only relieve pain but may also reduce the muscle spasms and anxiety.

• Electrode pads should not be placed on broken or damaged skin.
• Electrode pads should not be placed front or side of the neck, eyes or in the mouth.
• Should not be used in individuals with decreased pain sensation.
• Should not be used in the shower, tub or swimming pool.
• Should not be used while driving or operating machinery.

TENS should not be used on certain parts of the neck, eye or penis or without a physician’s approval. TENS is not approved for use in pregnant women or people who have pacemakers.

TENS is typically accessible as part of an integrated pain management program that may include physiotherapy, occupational and exercise therapy, cognitive behavioral therapy, pain medication, acupressure or acupuncture.