Alterations in electrical pain thresholds by use of acupuncture-like transcutaneous electrical nerve stimulation in pain-free subjects

Department of Physiology, University of Toronto, Ontario, Canada.

Acupuncture-like transcutaneous electrical nerve stimulation (ALTENS) was compared with a placebo treatment in altering acute electrical pain thresholds. Ten pain-free subjects underwent, on different days, an acclimatization session, an ALTENS treatment, and a placebo treatment in a cross-over design. Electrical sensation and pain thresholds were measured from the tip of the index finger bilaterally at 15-minute intervals twice before, once during, and three times after a 30-minute treatment session. The ALTENS treatment was given at 4 Hz at an intensity just below pain threshold delivered to acupuncture points in the hand and wrist. The placebo treatment was similarly delivered, except that the intensity of stimulation was just above sensation threshold. Neither the ALTENS treatment nor the placebo treatment produced a significant change in pain threshold. There was no correlation between initial pain threshold and change in pain threshold. Implications for the modulation of pain are discussed.