Journal of Pain Research (Jul 2020)
Hyperconnectivity and High Temporal Variability of the Primary Somatosensory Cortex in Low-Back-Related Leg Pain: An fMRI Study of Static and Dynamic Functional Connectivity
Abstract
Yixiu Pei,1,2 Yong Zhang,3 Yanyan Zhu,1,2 Yanlin Zhao,1,2 Fuqing Zhou,1,2 Muhua Huang,1,2 Lin Wu,1,2 Honghan Gong1,2 1Department of Radiology, The First Affiliated Hospital, Nanchang University, Nanchang 330006, People’s Republic of China; 2Neuroradiology Laboratory, Jiangxi Province Medical Imaging Research Institute, Nanchang 330006, People’s Republic of China; 3Department of Pain Clinic, The First Affiliated Hospital, Nanchang University, Nanchang, Jiangxi Province 330006, People’s Republic of ChinaCorrespondence: Fuqing ZhouDepartment of Radiology, The First Affiliated Hospital, Nanchang University, 17 Yongwaizheng Street, Nanchang, Jiangxi 330006, People’s Republic of ChinaTel +86 791 8869 5132Email [email protected]: To investigate the functional connectivity (FC) and its variability in the primary somatosensory cortex (S1) of patients with low-back-related leg pain (LBLP) in the context of the persistent stimuli of pain and numbness.Patients and Methods: We performed functional magnetic resonance imaging on LBLP patients (n = 26) and healthy controls (HCs; n = 34) at rest. We quantified and compared static FC (sFC) using a seed-based analysis strategy, with 6 predefined bilateral paired spherical regions of interest (ROIs) in the S1 cortex. Then, we captured the dynamic FC using sliding window correlation of ROIs in both the LBLP patients and HCs. Furthermore, we performed a correlational analysis between altered static and dynamic FC and clinical measures in LBLP patients.Results: Compared with controls, the LBLP patients had 1) significantly increased static FC between the left S1back (the representation of the back in the S1) and right superior and middle frontal gyrus (SFG/MFG), between the left S1chest and right SFG/MFG, between right S1chest and right SFG/MFG, between the left S1face and right MFG, and between the right S1face and right inferior parietal lobule (P < 0.001, Gaussian random field theory correction); 2) increased dynamic FC only between the right S1finger and the left precentral and postcentral gyrus and between the right S1hand and the right precentral and postcentral gyrus (P < 0.01, Gaussian random field theory correction); and 3) a negative correlation between the Barthel index and the increased static FC between the left S1face and right inferior parietal lobule (P = 0.048).Conclusion: The present study demonstrated the hyperconnectivity of the S1 cortex to the default mode and executive control network in a spatial pattern and an increase in the tendency for signal variability in the internal network connections of the S1 cortex in patients with LBLP.Keywords: primary somatosensory cortex, static functional connectivity, dynamic functional connectivity, chronic low-back-related leg pain, chronic pain, resting-state functional MRI
