Gray Matter Abnormalities in Patients with Chronic Low Back Pain: A Systematic Review and Meta-Analysis of Voxel-Based Morphometry Studies.

BACKGROUND: Numerous studies utilizing voxel-based morphometry (VBM) have documented gray matter (GM) alterations in patients with chronic low back pain (CLBP) compared to healthy controls. However, the inconsistency in GM abnormalities observed across different studies has hindered their potential application as objective neuroimaging biomarkers or therapeutic targets. To address this issue, we conducted a comprehensive meta-analysis of VBM studies to identify robust GM differences between CLBP patients and healthy controls. METHODS: The databases including PubMed, Embase, and Web of Science were systematically searched from January 2000 to September 2022 to identify eligible neuroimaging studies. In this coordinate-based meta-analysis of VBM studies, the Seed-based d Mapping with Permutation of Subject Images method was used to quantitatively assess regional differences in GM between CLBP patients and healthy controls. RESULTS: Thirteen VBM studies, involving a total of 574 CLBP patients and 1239 healthy controls, were included in the meta-analysis. The findings revealed that CLBP patients exhibited increased GM in the left striatum and left postcentral gyrus and decreased GM in the left superior frontal gyrus, left cerebellum, right striatum, left insula, and right middle occipital gyrus compared to healthy controls. The jackknife sensitivity analysis confirmed the robustness of these neuroimaging findings. CONCLUSIONS: This study provides new insights into potential treatment strategies for CLBP and identifies neuroimaging biomarkers for pain chronification. These findings highlight the importance of considering regional GM abnormalities in the development of clinical interventions for CLBP.

Long-term ANT-DBS effects in pilocarpine-induced epileptic rats: A combined 9.4T MRI and histological study.

Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) appears to be effective against seizures in animals and humans however, its therapeutic mechanisms remain elusive. This study aimed to combine 9.4T multimodal magnetic resonance imaging (MRI) with histology to investigate the longitudinal effects of long-term ANT-DBS in pilocarpine-induced epileptic rats. Status epilepsy (SE) was induced by LiCl-pilocarpine injection in 11 adult male Sprague-Dawley rats. Four weeks after SE, chronic epileptic rats underwent either ANT-DBS (n = 6) or sham-DBS (n = 5) surgery. Electroencephalography (EEG) and spontaneous recurrent seizures (SRS) were recorded for 1 week. The T2-weighted image and images from resting-state functional MRI (rs-fMRI) were acquired at three states: before SE, at 4 weeks post-SE, and at 5 weeks post-DBS. Volumes of the hippocampal subregions and hippocampal-related functional connectivity (FC) were compared longitudinally. Finally, antibodies against neuronal nuclei (NeuN) and glial fibrillary acidic proteins were used to evaluate neuronal loss and astrogliosis in the hippocampus. Long-term ANT-DBS significantly reduced seizure generalization in pilocarpine-induced epileptic rats. By analyzing the gray matter volume using T2-weighted images, long-term ANT-DBS displayed morphometric restoration of the hippocampal subregions. Neuronal protection of the hippocampal subregions and inhibition of astrogliosis in the hippocampal subregions were observed in the ANT-DBS group. ANT-DBS caused reversible regulation of FC in the insula-hippocampus and subthalamic nucleus-hippocampus. Long-term ANT-DBS provides comprehensive protection of hippocampal histology, hippocampal morphometrics, and hippocampal-related functional networks.

Gray Matter Alterations in Parkinson's Disease With Rapid Eye Movement Sleep Behavior Disorder: A Meta-Analysis of Voxel-Based Morphometry Studies.

Background: Gray matter (GM) alterations in Parkinson's disease (PD) patients with rapid eye movement sleep behavior disorder (RBD) have been demonstrated in many neuroimaging studies using voxel-based morphometry (VBM). However, the inconsistent findings between studies cannot be applied to clinical practice as a neuroimaging biomarker. We performed a meta-analysis of VBM studies at a whole-brain level to investigate GM differences between PD patients with and without RBD. Methods: A systematic search was conducted in PubMed, Embase, and Web of Science from inception to November 2019 to identify eligible VBM studies. We adopted the latest Seed-based d Mapping with Permutation of Subject Images technique to quantitatively estimate the difference of regional GM volume between PD patients with and without RBD. Results: We included five studies comprising 105 PD patients with RBD and 140 PD patients without RBD. The pooled meta-analysis revealed that PD patients with RBD showed a significant reduction of GM volume in the right superior temporal gyrus (STG) compared with those without RBD. This result was confirmed to be robust by the jackknife sensitivity analysis. Conclusion: Our finding shows significantly and robustly reduced GM volume in the right STG in PD patients with RBD, preliminarily suggesting the association of GM atrophy in this brain region with the occurrence of RBD in PD patients.