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Jose G. Veliz, M.D. M.S.A.
Medical Director
Palomar Pain Management Center
Pomerado Pain Management Center
Posted March 25, 2009 08:10 AM
Transcutaneous electrical nerve stimulation (TENS) is s form of electroanalgesia. Electroanalgesia involves the use of electrical impulses to certain parts of the body in order to block pain signals. Conditions for which the TENS unit has been used include the following:
Arthritis
CRPS (RSD)
Myofascial (muscle) pain
Low back pain
Post surgical pain
Post herpetic neuralgia
Trigeminal neuralgia
Atypical facial pain
Phantom limb pain
Acute post traumatic pain
Dysmenorrhea
Visceral Pain
The effectiveness of TENS in these conditions remains controversial due to the fact that properly performed studies have not been done.
Introduction:
The mechanism by which TENS decreases pain remains unknown. Theories include the following:
Levels of endorphins (natural pain reducers) are raised.
Nerves which carry pain signals are directly blocked.
The transmission of pain signals to the brain are blocked at the level of the spinal cord.
TENS unit design:
A TENS unit consists of the following components:
An electrical signal generator
A battery
A set of electrodes
Transcutaneous electrical stimulation (TENS) can be administered by a physical therapist, chiropractor or physician. A physician may prescribe a TENS unit. Generally, these units can be purchased or rented. The units are portable stimulators which can either be worn around the waist or in one’s pocket. The patient is instructed on the proper use of a TENS unit by a physical therapist, chiropractor or physician. Usually, the portable device is used on a rental or trial basis before it is purchased.
When a physical therapist uses a TENS unit to deliver topical steroid medication through the skin, it is called “iontophoresis.” The electrical stimulation facilitates the absorption of the topical steroid medication into soft tissue in order to decrease inflammation and pain. The cost of a TENS unit ranges from approximately $100 to several hundred dollars.
The settings for a TENS unit can be changed for the following:
Amplitude.
Pulse width (duration)
Pulse rate (frequency)
Patients are instructed to:
Vary the frequency.
Vary the intensity.
Properly position the electrodes.
Complications of a TENS unit are rare, but include the following:
Skin irritation
A TENS unit should not be used in the following situations:
In patients with demand type pacemakers
During pregnancy
Over the carotid sinuses (lateral neck)
Over the anterior neck
Over an area of sensory impairment which may increase the likelihood of burns
Clinical Use of TENS
Transcutaneous electrical stimulation (TENS) can be used for acute of chronic pain. The time of onset for pain relief, after a TENS unit is instituted, varies from almost immediate to hours. The duration of pain relief also varies considerably. Some patients obtain pain relief only while the TENS unit is being used, while others obtain pain relief for many hours afterwards. The amplitudes, pulse widths, pulse rates and electrode positioning also vary considerably among individuals with similar conditions.
Summary:
Transcutaneous electrical stimulation (TENS) is a commonly used form of electroanalgesia. Complications are rare when used with proper instruction. Although TENS is touted as an effective treatment for both acute and chronic pain, properly designed studies need to be performed in order to validate its use in these conditions.
References:
http://www.cochrane.org/reviews/en/ab/003222.html
http://emedicine.medscape.com/article/325107-print |
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