Acupuncture and chronic pain mechanisms.

Forty patients with chronic pain below the waist level not amenable to conventional medical and/or surgical treatment were randomly assigned to one or two different methods of acupuncture, after studying the underlying pain mechanisms using a Multidisciplinary Pain Clinic approach and the differential spinal block (DSB). One group received acupuncture needling in the classical acupuncture points referred to as meridian loci needling (MLN) and the other group received tender area needling (TAN) with needles inserted in the dermatomal distribution of the painful areas. The responses between the two groups showed no significant difference. Results were then related to the predetermined somatopsychological basis of the individual's pain problems as classified by the DSB. A group of patinets in whom pain relief occurred upon subarachnoid injection of 0.25% procaine followed by sympathetic blockade or 0.5% procaine injection followed by hypalgesia without motor loss, also reported maximum subjective improvement in their pain level following acupuncture therapy performed at a later time. The other group of patients in whom pain persisted despite sensory and motor blockade (1% procaine) responded very poorly to acupuncture therapy. DSB was found to be complimentary to acupuncture therapy in that it facilitated patient selection for the therapy.