Wrist-ankle Acupuncture Increases Pain Thresholds in Healthy Adults.

Context • Wrist-ankle acupuncture (WAA) has been used to relieve both chronic and acute pain in China. Some research has shown that WAA can increase the pain thresholds in pain patients, but the ability of WAA to affect the pain thresholds in healthy adults is unknown. Objective • The study intended to assess the influence of WAA on the pain thresholds of healthy adults. Design • This is an observational study. Setting • This study was conducted in the School of Traditional Chinese Medicine at the Second Military Medical University (Shanghai, China). Participants • Participants were 50 healthy university students aged 19-23 y. Intervention • In the theory of WAA, each side of the body and each limb are longitudinally divided into 6 regions, with 1 needling point defined for each region at the wrist or ankle. The theory indicates that needling a point should relieve pain in a point's corresponding region. For the study, a needle was inserted and retained for 30 min in the Upper 2 point of the left wrist of each participant. Outcome Measures • The pressure pain threshold was measured by a handheld algometer at a position in the left Upper 2 region corresponding to the site of the needling and at positions in the right Upper 2 region as well as the left and right Upper 3 regions not corresponding to the site of the needling. The measurements were taken at 40 min before needling, 5 min after needling, 30 min after needling when the needles were removed, and 70 min after needling. Results • The immediate influence of the WAA on the pain threshold was not significant at 5 min after needling (P > .05). However, at 30 min after needling when the needles were removed, the increases in the pain thresholds were statistically significant when compared to those at 40 min before needling, which were the measurements at baseline (P ≤ .01). At 70 min after needling, the pain thresholds remained higher than those at 40 min before needling (P < .05). From 40 min before needling to 70 min after needling, the pain thresholds in the different positions showed a continuous increase. Conclusions • The WAA had an analgesic effect on pressure-induced pain not only in the corresponding but also in the noncorresponding regions of the needling point in healthy adults. The immediate analgesic effect of the WAA at 5 min after needling was not obvious, but the effects at 30 min and 70 min after needling were statistically significant.