Pain modulation induced by electronic wrist-ankle acupuncture: A functional near-infrared spectroscopy study.

Abstract

As a new technology, electronic wrist-ankle acupuncture (E-WAA) combines the advantages of wrist-ankle acupuncture and transcutaneous electrical nerve stimulation, but the analgesic effect and mechanism need to be clarified. The purpose of this study was to identify the pain modulation caused by E-WAA by evaluating the response of the prefrontal cortex (PFC) from the perspective of neurophysiology. Fifty male volunteers (age 25.00±1.05years) with trapezius myofascial pain syndrome were randomly allocated into intervention group (E-WAA treatment) or sham control group at a 1:1 ratio. An outcome evaluation system was used to induce tenderness on the Jianjing point and record the pain value. A multichannel functional near-infrared spectroscope was used to detect the PFC activation during tenderness before and after treatment to demonstrate the neuromodulation mechanism. A general linear model and t-test (p<0.05) were used to analyze the difference in the oxyhemoglobin (HbO) concentration and pain value. In the intervention group, the pain value of volunteers decreased significantly (p=0.017) after E-WAA treatment, whereas there was no statistical difference (p=0.082) in the sham group. Before treatment, the frontopolar (FP) and dorsolateral prefrontal cortex (DLPFC) were the activation areas of the PFC. The E-WAA treatment then suppressed the activation of the two areas. The HbO concentration of the FP and DLPFC changed from a sharp rise during tenderness to not changing with tenderness stimulation. The results demonstrated that the E-WAA have a great analgesic effect. The FP and DLPFC were relative to the analgesia neuromodulation induced by the E-WAA.