Pain threshold changes following acupuncture, measured with cutaneous argon laser and electrical tooth pulp...

1. The present study compared the argon laser technique for pain threshold measurements with the previously often used threshold measurements with electrical tooth pulp (TP) stimulation. 2. Conditioning stimuli with acupuncture was given since it previously has been shown to induce pain threshold changes. Acupuncture needles were inserted in the hands and arms and electrically stimulated. 3. The experiments were performed in a single blind fashion comparing pain threshold effects after either acupuncture or placebo. Pain threshold measurements with a method of limits were used with both electrical TP and the argon laser method. 4. In comparison to placebo the pain thresholds increased after acupuncture, both on the face and on the hand, with the argon laser method, while the TP thresholds were not influenced. No significant pain threshold change was detected with either the argon laser or the TP method following placebo treatment. 5. The results indicate that the argon laser used for sensory testing with a method of limits is a useful method for pain threshold measurements. The difference in pain threshold effects induced by acupuncture measured with the argon laser and the TP stimulation, are discussed and related to mechanisms that may differ between the two types of pain threshold measurements.