Auricular Acupressure Can Modulate Pain Threshold.

The objective of our study was to investigate if auriculotherapy (AT) can modulate pain threshold. In our experiments, AT consisted of placing Vaccaria seeds over the "fingers point" of one ear. Two groups of healthy volunteers were enrolled for the study. Each subject was asked to perform an autoalgometric test developed by our group on three occasions: before, 1 hour after, AT and 24 hours after AT. Participants of the first group received a 2-minute long session of AT, while participants of the second group received a 2-minute long session of sham treatment, consisting of a puncture/massage above the skin of the neck. The autoalgometric test consisted of applying an increasing pressure with the finger-tips and finger-backs of four fingers by the subjects themselves (i.e., eight sites were evaluated) against a round-shaped needle for two times: until a minimum pain sensation (first time, minimal test) or a maximally tolerable pain sensation (second time, maximal test). Our results showed a significant higher pain threshold in the maximal test at 24 hours after AT compared to sham treatment. This result indicates for the first time that AT can increase pain tolerability, rather than affecting the minimal pain threshold.