The Duration of Chronic Pain Can Affect Brain Functional Changes of the Pain Matrix in Patients with Chronic Back Pain: A Resting-State fMRI Study

Abstract

Purpose: This study was conducted to explore the differences in functional changes in the pain matrix in patients with chronic back pain (CBP) at different stages and identify whether these brain changes were related to the pain duration. Patients and Methods: In this study, 29 healthy individuals and 54 patients with CBP were recruited. According to the pain duration, 25 patients (3 to 12 months) were divided into the CBP-S group and 29 patients (≥ 24 months) were divided into the CBP-L group. All subjects completed clinical pain-related measurement and functional magnetic resonance imaging (fMRI) scans. Moreover, the amplitude of low-frequency fluctuation (ALFF), functional connectivity (FC), and correlation analysis were conducted in this study. Results: Compared with healthy controls, patients in the CBP-L group showed significantly decreased ALFF in the left precuneus. In the FC analysis, patients in the CBP-S and CBP-L groups showed significantly decreased FC in several regions in the bilateral orbitofrontal cortices (OFC) and the left ventral posterior insula. Moreover, there were significant differences in the FC between the left hyper granular insula and the probabilistic area in OFC in pairwise group comparisons. The correlation analysis results demonstrated that pain duration was correlated with these functional brain changes, and the ANCOVA results revealed that pain intensity and pain interference scores did not affect the FC analysis results. Conclusion: There are different changes in the pain neural matrix in patients with chronic pain at different stages. Furthermore, the pain duration is related to brain functional changes.