Specific Correlation between the Hegu Point (LI4) and the Orofacial Part: Evidence from an fMRI Study

Acupoint specificity is a foundational concept in acupuncture theory. It is closely related to the function of the acupoint. In this study, we sought to probe the central mechanisms of the specific correlation between LI4 and orofacial part in Bell's palsy patients. In total, 36 patients with left Bell's palsy were divided into three groups in random order, and each group received transcutaneous electrical acupoint stimulation (TEAS) at only one of three acupoints (LI4, ST6, and a sham point). A single-block fMRI design paradigm was applied to separately detect neural activity related to different stages of TEAS (prestimulation resting state, stimulation, and poststimulation resting state). Functional magnetic resonance imaging data were acquired during TEAS. There were extensive neuronal activities in the LI4 and ST6 groups and significant differences between stimulation at real and sham points. Brain regions were activated more by real acupoint TEAS than by sham point TEAS. Brain regions that were activated with LI4 and ST6 were broadly overlapping and adjacent. Our results provide supplementary neuroimaging evidence for the existence of acupoint specificity. These results may confirm the central mechanisms of the specific correlation between the Hegu point and the orofacial part.