Acupuncture is a form of medical therapy that involves inserting thin, solid needles into selective sites on the surface of the body. It has been part of Chinese medicine since ancient times (see MEDICINE, TRADITIONAL). Outside China, acupuncture was long used in overseas Chinese communities, but Western interest in it did not become widespread until the 1970s, when physicians in China demonstrated that it could be used to control surgical pain.

The early Chinese postulated a system of energy circulation that predated by many centuries current understanding of blood circulation and the nervous system. They thought that vital life energy flows through a series of pathways, or meridians, 12 of which were on each side of the body. Meridians were said to course through the deep tissues of the body, surfacing occasionally. The areas where the meridians touch the surface were considered useful treatment points for diseases, which were thought to be caused by imbalances in the energy flow. Inserting a needle into certain points could increase energy flow, and the needles also were used to drain away excessive pressure or to break down blocks or dams in energy flow. Meridians were variously related to the heart, the lungs, the colon, the gallbladder, the liver, and the other organs. The flow of energy in each meridian was read by taking the pulse associated with it at the wrist. Therapy was aimed at restoring normal energy flow so that perfect equilibrium existed throughout the body.

The use of acupuncture for controlling surgical pain is a recent development in China, and it does not strictly reflect the ancient medical philosophy. Classical Chinese medicine concerned itself with restoring normal function as opposed to creating abnormal conditions, such as total pain reduction. To control surgical pain in contemporary China, needles are inserted into various parts of the body, and the patient is stimulated by electrical current delivered through the needles or by the more traditional manual twirling of the needles. Practitioners may also inject various solutions at these body sites or use ultrasonic probes instead of needles. After about 20 minutes of stimulation, the surgery can begin. If acupuncture treatment has been effective, the patient will be wide awake, alert, and aware of all the major surgical procedures but will experience little or no pain (see ANESTHETICS).

The mechanisms by which patients are able to tolerate surgery during acupunctural stimulation are still unknown. Some scientists speculate that large sensory fibers are activated, which inhibit transmission of impulses from the small fibers carrying the sensory input of pain. Other scientists speculate that naturally produced morphinelike substances--endorphins and enkephalins--may be released within the brain in response to acupuncture. When these substances bind to OPIATE RECEPTOR cells, a pain-inhibition system is activated.

Acupuncture is highly effective in giving short-term relief to patients suffering chronic pain from backache, headache, or abdominal pain. A small percentage of American physicians are adding acupuncture to their therapeutic methods because it is safe, it works well for certain problems, and it is an alternative to treatment by medications that have undesirable side effects.