Effect of acupuncture upon experimentally induced ischemic pain: A sham-controlled single-blind study

Objective: To investigate the hypoalgesic effect of true and sham acupuncture upon experimentally induced ischemic pain. Design: Human volunteers (n = 60) were required to attend two sessions for pain induction using a submaximal effort tourniquet technique; on the first occasion, baseline pain scores were recorded and on the second, 48 hours later, subjects were randomly allocated to one of five groups: Control, Treatment Groups 1 or 2, or Placebo Groups 1 or 2. Subjects: Healthy human volunteers. Intervention: In all the Treatment and Placebo Groups, subjects received some form of needle acupuncture 15 minutes before, and 5 minutes during, the pain induction procedure on the second day. Treatment Group 1 received acupuncture on acupuncture points situated distal to the tourniquet, whereas Treatment Group 2 received acupuncture on acupuncture points situated proximal to the tourniquet. In Placebo Groups 1 and 2, subjects received 'sham' acupuncture either on nonacupuncture points (Placebo Group 1) or on acupuncture points (Placebo Group 2) using (standardized) minimal levels of stimulation. A licensed acupuncturist who was not involved in data collection and analyses carried out all treatments. Outcome Measures: Pain was assessed using a computerized visual analog scale (VAS) and a McGill Pain Questionnaire (MPQ). Results: Analysis of VAS scores using ANOVA revealed no significant differences between groups (e.g., VAS sum of differences data (mean +/- SEM): Treatment Group 1: 90+/-47, Treatment Group 2: 187+/-56, Placebo Group 1: 152+/-40, Placebo Group 2: 121+/-42, Controls: 46+/-24, p>0.05). Analysis of MPQ percentage difference scores using one-way ANOVA revealed some isolated effects in the subjective descriptors and the Pain Rating Index, both for Treatment Group 2 and Placebo Group 2, proving them superior to any of the other groups. Conclusion: The results of the study provide no convincing evidence for a superior hypoalgesic effect of acupuncture compared with "sham" procedures on this model of experimental pain.