Acupuncture Treatment of Chronic Low Back Pain Reverses An Abnormal Brain Default Mode Network in Correlation with Clinical Pain Relief

Abstract

Background Acupuncture is gaining in popularity as a treatment for chronic low back pain (cLBP); however, its therapeutic mechanisms remain controversial, partly because of the absence of an objective way of measuring subjective pain. Resting-state functional MRI (rsfMRI) has demonstrated aberrant default mode network (DMN) connectivity in patients with chronic pain, and also shown that acupuncture increases DMN connectivity in pain-modulator and affective-emotional brain regions of healthy subjects. Objective This study sought to explore how cLBP influences the DMN and whether, and how, the altered DMN connectivity is reversed after acupuncture for clinical pain. Methods RsfMRI data from 20 patients with cLBP, before and after 4 weeks of treatment, and 10 age- and gender-matched healthy controls (without treatment) were analysed using independent components analyses to determine connectivity within the DMN, and combined with correlation analyses to compute covariance between changes in DMN connectivity and changes in clinical pain. Visual analogue scale data were assessed to rate clinical pain levels. Results Less connectivity within the DMN was found in patients with cLBP than in healthy controls, mainly in the dorsolateral prefrontal cortex, medial prefrontal cortex, anterior cingulate gyrus and precuneus. After acupuncture, patients’ connectivities were restored almost to the levels seen in healthy controls. Furthermore, reductions in clinical pain were correlated with increases in DMN connectivity. Conclusions This result suggests that modulation of the DMN by acupuncture is related to its therapeutic effects on cLBP. Imaging of the DMN provides an objective method for assessment of the effects of acupuncture-induced analgesia.