Acupuncture has been a medical practice in China for several thousand years. In ancient times, pointed stone slivers were used. With time metal probes were developed, but much coarser than the fine needles presently used. Acupuncture has been used to treat various diseases, including appendicitis, bacillary dysentery, gastric ulcer, cholelithiasis, hypertension, poliomyelitis, insomnia, malaria, and even epilepsy. Although good success rates have been claimed for treatment of these and other diseases, owing to natural remission of some diseases during the long course of treatment some results are questionable. For instance, little or no significant difference has been observed in the success rates of acupuncture versus placebo treatment (administration of vitamin B) for malaria. In contrast, there is little doubt of the analgesic effect of acupuncture. Pain is relieved immediately after needling of the acupuncture points in many cases, particularly cases of pain caused reflexly by a certain injury. Pain thresholds have been observed to be elevated by acupuncture in normal human subjects (Chiang et al., 1973). Acupuncture has also been employed instead of anaesthesia for surgical operations, though with restrictions.
The physiological basis of acupuncture analgesia has been extensively studied in China, but only some of these results have been introduced to the Western world (Nathan, 1978; Han & Terenius, 1982). The present chapter summarizes work related to mechanisms of acupuncture analgesia from the neurophysiological point of view, with particular emphasis on the descending inhibitory systems involved.