Background

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 electronic wrist-ankle acupuncture by evaluating the response of prefrontal cortex (PFC) from the perspective of neurophysiology.

Methods

50 male volunteers (age 25.00±1.05 years) 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 prefrontal cortex 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.

Results

In the intervention group, the pain value of volunteers decreased significantly (p=0.017) after E-WAA treatment, while 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.

Conclusion

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.