Acupuncture modulates brain neural activity in patients: a systematic review and meta-analysis

Using fMRI, the acupuncture studies related with modifying disease process in patients still stay in the beginning, whereas the physiological response to acupuncture has been published abundantly. In this study, we reviewed acupuncture studies performed in patient and reported the changes of brain activity using fMRI. Only randomized controlled studies were included. We systemically searched PubMed and EMBASE and extracted data by two independent researchers. We also performed an ALE-meta analysis to investigate significant brain responses of acupuncture. Fifteen studies were finally included in our review. The studies were performed in stroke, carpal tunnel syndrome, migraine, irritable bowel syndrome, lumbar disc herniation, Parkinson’s disease (PD) and mild cognitive impairment. The common changes of brain activity by acupuncture were identified in the sensory system and insular cortex, whereas other brain regions showed heterogeneous activity according to each disease status. Meta-analysis indicated the different brain responses between verum and sham acupuncture were found in the frontal lobe (BA 6) in the brain disorders such as stroke and PD and the parietal lobe (BA 40), insula (BA 13), limbic lobe (BA 23) and occipital lobe (BA 18) in the pain related disease. However, the correlations between the changes of clinical symptoms and brain activities are limited. Some specific changes of brain activities induced by acupuncture can be detective through patient imaging studies. However, it was difficult to draw an obvious conclusion due to the heterogeneity of the diseases and the interventions. Further well-designed patient centered fMRI studies considering clinical points are required.