Acupuncture induced changes of the pressure pain threshold are mediated by segmental inhibition - a randomized controlled trial.

Our aim was to distinguish between spinal and supraspinal mechanisms in the intact nervous system by comparing homo- and heterosegmental effects of electroacupuncture and manual acupuncture on sensory perception in healthy volunteers by means of Quantitative Sensory Testing (QST).Seventy two healthy volunteers were randomly assigned to receive either manual acupuncture (MA) or electroacupuncture (EA) at SP 6, SP 9, GB 39 and ST 36 at the left leg or relaxed for 30 min (control group, CG). Blinded examiners assessed 13 sensory modalities (thermal and mechanical detection and pain thresholds) at the upper arms and lower legs before and after the intervention by means of a standardized QST battery. Change scores of all 13 sensory thresholds were compared between groups. The main outcome measure was the change score of the pressure pain threshold (PPT).There were no baseline differences between groups. PPT change scores at the lower left leg, in the same segment as the needling site, differed significantly (p = 0.008) between the EA group (median 103.01 kPa) and the CG (median 0.00 kPa) but not between the MA group (median 0.00 kPa) and the CG. No further significant change score differences were found between one of the acupuncture groups and the CG.The PPT can be changed by EA. The PPT increase was confined to the segment of needling, which indicates that it is mainly mediated by segmental inhibition in the spinal cord. This underscores the importance of segmental needling and electrical stimulation in clinical practice.
PMID: 26133726