The Effects of Stimulation of Ear Acupuncture Points on the Body's Pain Threshold

Abstract

Six ear acupuncture points, one non-acupuncture ear point, and the body locus Ho-Ku (LI-4) were electrically stimulated in order to compare the effects of stimulation on the body's pain threshold at selected loci on various points on the body by measurement with a radiation heat-type Pain Meter on 5 subjects. The ear points, with the exception of the non-acupuncture ear point, were found to be effective even in peripheral body regions in varying degrees. Ear stimulation did not increase the threshold as rapidly as Ho-Ku. In all cases where the pain threshold was raised, the effect persisted after electrical stimulation had stopped.

Effects of Acupuncture on Sensory Perception: A Systematic Review and Meta-Analysis

“…Of the ten studies comparing close to distant needling, eight (80%) showed a larger increase of at least one sensory threshold close to the needling location [35,51,53,67,83,101,102,105]. In six out of eleven studies (54.5%), threshold changes were more pronounced after ipsi-than after contralateral needling [25,34,67,[100][101][102].…”

“…In nine other studies (18.8%) no effect was observed neither after verum nor after sham acupuncture [22, 27, 42, 47-49, 99, 103, 104], and the results of three studies (6.3%) were rated as unclear [35,44,45]. None of the twelve studies including both control modalities found significant differences between the sham and the inert control group [24,25,27,30,35,42,47,53,57,62,85,99], although in three of these studies, the pre-post comparison indicates larger effects in the sham than in the inert control group [24,30,53,85].…”

“…In six out of eleven studies (54.5%), threshold changes were more pronounced after ipsi-than after contralateral needling [25,34,67,[100][101][102]. In one high quality study bilateral needle placement was superior to unilateral needling [65], and results of three studies suggest that needle stimulation at LI 4 is more effective in changing pain thresholds than needling at other acupuncture points [39,53,65]. Four studies (20%) found significant effects of acupuncture on sensory perception independent of the needle location [28,60,66,75,95], and in two studies no change of any sensory threshold was observed [103,104].…”

“…Heterogeneity was found to be substantial in both analyses. superior to sham acupuncture, but no statistical analysis was provided [53,94]. In nine studies (18.8%) both, verum and sham acupuncture, had a significant effect on the respective sensory threshold [43,61,62,66,73,76,77,86,98].…”

“…Seventeen of these studies (70.8%) focused on the effect of EA only [30, 34, 36, 42, 53-55, 61, 66, 69, 80, 85, 90, 94, 101, 102, 105], five studies (20.8%) on the effect of MA only [31,32,35,67,99], and two studies (8.3%) evaluated both treatment methods . Of the 19 studies evaluating EA, 15 (78.9%) indicated an elevation of the HPT [30,34,53,54,60,61,66,80,85,90,94,[100][101][102]105] such as did five of seven (71.4%) MA studies [31,32,60,67,100].…”