rTMS Pain Reduction Effectiveness in Non-specific Chronic Low Back Pain Patients using rs-fMRI Functional Connectivity

Purpose Non-specific chronic low back pain (CLBP) is the most common form of CLBP without clear clinical evidence. This study evaluated the effectiveness of repetitive transcranial magnetic stimulation (rTMS) as a noninvasive technique for pain reduction in non-specific CLBP using functional connectivity (FC) method. Methods Fifteen participants with non-specific CLBP received 20 Hz rTMS over the motor cortex. The pain intensity was measured using a Visual Analog Scale (VAS), and brain functional scans were obtained before and after brain stimulation. The percentage pain reduction (PPR%) and the FC differences in the insula (INS), thalamus (THA), supplementary motor area (SMA), and anterior cingulate cortex (ACC) were determined using paired t-test analysis. The correlation between PPR% and FCs was explored using the Pearson correlation coefficient. Results Pain intensity reduced significantly after rTMS (P < 0.05). FC between bilateral SMA and ACC, and bilateral INS decreased while the FC between bilateral INS and bilateral THA increased following rTMS. Moreover, there was a negative correlation between the FC of INS (R)-SMA (R) and that of PPR% (r=-0.56). Conclusion FC between SMA and INS was associated with analgesia of rTMS in non-specific CLBP, indicating the potential role of FC as a novel objective parameter to predict the outcome of clinical use of rTMS for pain relief in CLBP patients.