The analgesic effects of acupuncture on experimental pain threshold and somatosensory evoked potentials in healthy volunteers

Recently, the analgesic effects of acupuncture have been brought into question, mainly because of the methodological inadequacies of previous studies. This single-blind placebo-controlled study examined the effects of manual acupuncture administered at a point related to the site of electrically induced pain at the finger (i.e. Pericardium 6) and a point unrelated to the site of electrically induced pain (i.e. Gallbladder 20) in normal subjects. The effects of acupuncture on the amplitudes of the late waveform components of the somatosensory evoked potentials elicited by painful electrical stimulation of the index finger were also examined. The main findings of this study were that, when compared to sham acupuncture or control groups, acupuncture administered at either Pericardium 6 or Gallbladder 20 did not significantly change: (i) sensory detection threshold, pain threshold or pain tolerance to electrically induced pain administered to the index finger, and (ii) P1N1 or N1P2 amplitudes of late latency waveform components of the somatosensory evoked potentials elicited by a painful electrical stimulus delivered to the index finger. Although acupuncture appears to be successful in relieving the pain of many chronic pain sufferers, these findings substantiate recent meta-analyses which conclude that the analgesic effects of acupuncture under placebo-controlled conditions remain in doubt. Our results should serve as an incentive for further research into the analgesic effects of acupuncture under placebo-controlled conditions.