Functional disruptions of the brain network in low back pain: a graph-theoretical study.

PURPOSE: The aim of this study was to investigate alterations in the topological organization of whole-brain functional networks in patients with chronic low back pain (CLBP) and characterize the relationship of these alterations with pain characteristics. METHODS: Thirty-three CLBP patients and 34 matched healthy controls (HCs) underwent fMRI scans. A graph-theoretical approach was applied to identify brain network changes in patients suffering from chronic low back pain given its nonspecific etiology and complexity. Graph theory-based analysis was used to construct functional connectivity matrices and extract the features of small-world networks of the brain in both groups. Then, the whole-brain functional connectivity differences were characterized by network-based statistics (NBS) analysis, and the relationship between the altered brain features and clinical measures was explored. RESULTS: At the global level, patients with CLBP showed significantly decreased gamma, sigma, global efficiency, and local efficiency and increased lambda and shortest path length compared with HCs. At the regional level, there were deficits in nodal efficiency within the default mode network and salience network. NBS analysis demonstrated that decreased functional connectivity was present in the CLBP patients, mainly in the frontolimbic circuit and temporal regions. Furthermore, aspects of topological dysfunctions in CLBP were correlated with pain severity. CONCLUSION: This study highlighted the aberrant topological organization of functional brain networks in CLBP, which may shed light on the pathophysiology of CLBP and support the development of pain management approaches.

Altered habenular connectivity in chronic low back pain: An fMRI and machine learning study.

The habenula has been implicated in the pathogenesis of pain and analgesia, while evidence concerning its function in chronic low back pain (cLBP) is sparse. This study aims to investigate the resting-state functional connectivity (rsFC) and effective connectivity of the habenula in 52 patients with cLBP and 52 healthy controls (HCs) and assess the feasibility of distinguishing cLBP from HCs based on connectivity by machine learning methods. Our results indicated significantly enhanced rsFC of the habenula-left superior frontal cortex (SFC), habenula-right thalamus, and habenula-bilateral insular pathways as well as decreased rsFC of the habenula-pons pathway in cLBP patients compared to HCs. Dynamic causal modelling revealed significantly enhanced effective connectivity from the right thalamus to right habenula in cLBP patients compared with HCs. RsFC of the habenula-SFC was positively correlated with pain intensities and Hamilton Depression scores in the cLBP group. RsFC of the habenula-right insula was negatively correlated with pain duration in the cLBP group. Additionally, the combination of the rsFC of the habenula-SFC, habenula-thalamus, and habenula-pons pathways could reliably distinguish cLBP patients from HCs with an accuracy of 75.9% by support vector machine, which was validated in an independent cohort (N = 68, accuracy = 68.8%, p = .001). Linear regression and random forest could also distinguish cLBP and HCs in the independent cohort (accuracy = 73.9 and 55.9%, respectively). Overall, these findings provide evidence that cLBP may be associated with abnormal rsFC and effective connectivity of the habenula, and highlight the promise of machine learning in chronic pain discrimination.

Abnormal Anatomical and Functional Connectivity of the Thalamo-sensorimotor Circuit in Chronic Low Back Pain: Resting-state Functional Magnetic Resonance Imaging and Diffusion Tensor Imaging Study.

Thalamocortical dysfunction is thought to underlie the pathophysiology of chronic pain revealed by electroencephalographic studies. The thalamus serves as a primary relay center to transmit sensory information and motor impulses via dense connections with the somatosensory and motor cortex. In this study, diffusion tensor imaging (DTI) (probabilistic tractography) and resting-state functional magnetic resonance imaging (functional connectivity) were used to characterize the anatomical and functional integrity of the thalamo-sensorimotor pathway in chronic low back pain (cLBP). Fifty-four patients with cLBP and 54 healthy controls were included. The results suggested significantly increased anatomical connectivity of the left thalamo-motor pathway characterized by probabilistic tractography in patients with cLBP. Moreover, there was significantly altered resting-state functional connectivity (rsFC) of bilateral thalamo-motor/somatosensory pathways in patients with cLBP as compared to healthy controls. We also detected a significant correlation between pain intensity during the MRI scan and rsFC of the right thalamo-somatosensory pathway in cLBP. Our findings highlight the involvement of the thalamo-sensorimotor circuit in the pathophysiology of cLBP.

Altered effective connectivity within the cingulo-frontal-parietal cognitive attention networks in chronic low back pain: a dynamic causal modeling study.

Dysfunction of the cingulo-frontal-parietal (CFP) cognitive attention network has been associated with the pathophysiology of chronic low back pain (cLBP). However, the direction of information processing within this network remains largely unknown. We aimed to study the effective connectivity among the CFP regions in 36 cLBP patients and 36 healthy controls by dynamic causal modeling (DCM). Both the resting-state and task-related (Multi-Source Interference Task, MSIT) functional magnetic resonance imaging (fMRI) data were collected and analyzed. The relationship between the effective connectivity of the CFP regions and clinical measures was also examined. Our results suggested that cLBP had significantly altered resting-state effective connectivity of the prefrontal cortex (PFC)-to-mid-cingulate cortex (MCC) (increased) and MCC-to-left superior parietal cortex (LPC) (decreased) pathways as compared with healthy controls. MSIT-related DCM suggested that the interference task could significantly increase the effective connectivity of the right superior parietal cortex (RPC)-to-PFC and RPC-to-MCC pathways in cLBP than that in healthy controls. The control task could significantly decrease the effective connectivity of the MCC-to-LPC and MCC-to-RPC pathways in cLBP than that in healthy controls. The endogenous connectivity of the PFC-to-RPC pathway in cLBP was significantly lower than that in healthy controls. No significant correlations were found between the effective connectivity within CFP networks and pain/depression scores in patients with cLBP. In summary, our findings suggested altered effective connectivity in multiple pathways within the CFP network in both resting-state and performing attention-demanding tasks in patients with cLBP, which extends our understanding of attention dysfunction in patients with cLBP.

Altered Amygdala-prefrontal Connectivity in Chronic Nonspecific Low Back Pain: Resting-state fMRI and Dynamic Causal Modelling Study.

Chronic nonspecific low back pain (cNLBP) is a leading contributor to disease burden worldwide that is difficult to treat due to its nonspecific aetiology and complexity. The amygdala is a complex of structurally and functionally heterogeneous nuclei that serve as a key neural substrate for the interactions between pain and negative affective states. However, whether the functions of amygdalar subcomponents are differentially altered in cNLBP remains unknown. Little attention has focused on effective connectivity of the amygdala with the cortex in cNLBP. In this study, thirty-three patients with cNLBP and 33 healthy controls (HCs) were included. Resting-state functional connectivity (rsFC) and effective connectivity of the amygdala and its subregions were examined. Our results showed that the patient group exhibited significantly greater rsFC between the left amygdala and left dorsal medial prefrontal cortex (mPFC), which was negatively correlated with pain intensity ratings. Subregional analyses suggested a difference located at the superficial nuclei of the amygdala. Dynamic causal modelling revealed significantly lower effective connectivity from the left amygdala to the dorsal mPFC in patients with cNLBP than in HCs. Both groups exhibited stronger effective connectivity from the left amygdala to the right amygdala. In summary, these findings not only suggested altered rsFC of the amygdala-mPFC pathway in cNLBP but also implicated an abnormal direction of information processing between the amygdala and mPFC in these patients. Our results further highlight the involvement of the amygdala in the neuropathology of cNLBP.

Larger regional volume of the thalamus in diarrhea-predominant irritable bowel syndrome: a cross-sectional study.

As a relay center between the cerebral cortex and various subcortical brain areas, the thalamus is repeatedly associated with the dysfunction of brain-gut interaction in patients with irritable bowel syndrome (IBS). However, the regional morphological alterations of the thalamus in IBS are not well defined. We acquired structural magnetic resonance data from 34 patients with IBS and 34 demographically similar healthy subjects. Data processing was performed using FMRIB's Integrated Registration and Segmentation Tool (FIRST). Volumetric analysis and surface-based vertex analysis were both carried out to characterize the morphology of the thalamus and other subcortical structures. Our results suggested that the majority (31 cases) of the patients with IBS had diarrhea-predominant symptoms. Volumetric analysis revealed a larger normalized volume of the right thalamus and left caudate nucleus in patients with IBS than in healthy controls. Surface analysis indicated that the difference arose mainly from the laterodorsal nucleus of the right thalamus, and the body of the left caudate nucleus. In addition, patients with IBS had different hemispheric asymmetries of the thalamus (rightward) and caudate nucleus (leftward) from controls (leftward for the thalamus and rightward for the caudate nucleus). In general, our results indicated that patients with diarrhea-predominant IBS had enlarged thalamus and caudate nucleus volumes, as well as altered hemispheric asymmetries of these two structures, compared with healthy controls. The neuroimaging evidence of these structural alterations helps clarify the underlying pathophysiology of diarrhea-predominant IBS.

Radiographic findings of hemolymphangioma in four patients: A case report.

Due to the rarity of hemolymphangioma, a limited number of cases of the disease have been reported in the literature thus far. The present case report describes the cases of 4 patients with hemolymphangioma that were diagnosed and treated at the Second Affiliated Hospital of Xi'an Jiaotong University (Xi'an, China). All patients were female, with a mean age of 44.7 years and a mean duration of symptoms prior to diagnosis of 2.7 years. The diagnosis of hemolymphangioma was determined by postoperative histopathology in all patients. A total of 2 patients were diagnosed with tumors that exhibited cystic characteristics (one in the mediastinum and the other in the neck), which was determined by computed tomography and magnetic resonance imaging. Another of the patients' tumors was located in the left forearm, and 1 patient had multifocal hemolymphangioma in the mediastinum and spleen. All patients underwent surgery and were asymptomatic during the follow-up periods (range, 8-15 months). In the present case report, the radiographic findings of the 4 cases are presented, including the unusual imaging characteristics that were observed, and relevant reports in the literature are discussed.

[Brain gray matter abnormalities revealed by voxel-based morphometry in patients with chronic low back pain].

OBJECTIVE: To explore the morphometric abnormalities of brain gray matter (GM) in patients with chronic low back pain (CLBP). METHODS: Thirty patients with CLBP and 30 healthy individuals were enrolled and examined with a 3.0 T magnetic resonance (MR) scanner. High-resolution T1 structural MR data were acquired and data analysis was performed using voxel-based morphometry (VBM) in FMRIB Software Library. The morphological differences were compared between the two groups. RESULTS: s Compared with the healthy control subjects, patients with CLBP showed decreased GM volumes in several brain cortical areas including the bilateral superior frontal gyrus, right frontal pole, left insular cortex, left middle and left inferior temporal gyrus (P<0.05, after TFCE correction). Increased GM volumes were found in the patients in the subcortical structures including the left thalamus, bilateral putamen, bilateral nucleus accumben and right caudate nucleus (P<0.05, after TFCE correction). CONCLUSION: Patients with CLBP have different patterns of GM abnormalities in different brain regions, characterized by reduced GM volume in cerebral cortical regions and increased GM volume in the subcortical nuclei. Such changes might be associated with the maladaptation of the brain in chronic pain state.

Abnormal Subcortical Brain Morphology in Patients with Knee Osteoarthritis: A Cross-sectional Study.

Despite the involvement of subcortical brain structures in the pathogenesis of chronic pain and persistent pain as the defining symptom of knee osteoarthritis (KOA), little attention has been paid to the morphometric measurements of these subcortical nuclei in patients with KOA. The purpose of this study is to explore the potential morphological abnormalities of subcortical brain structures in patients with KOA as compared to the healthy control subjects by using high-resolution MRI. Structural MR data were acquired from 26 patients with KOA and 31 demographically similar healthy individuals. The MR data were analyzed by using FMRIB's integrated registration and segmentation tool. Both volumetric analysis and surface-based shape analysis were performed to characterize the subcortical morphology. The normalized volumes of bilateral caudate nucleus were significantly smaller in the KOA group than in the control group (P = 0.004). There was also a trend toward smaller volume of the hippocampus in KOA as compared to the control group (P = 0.027). Detailed surface analyses further localized these differences with a greater involvement of the left hemisphere (P < 0.05, corrected) for the caudate nucleus. Hemispheric asymmetry (right larger than left) of the caudate nucleus was found in both KOA and control groups. Besides, no significant correlation was found between the structural data and pain intensities. Our results indicated that patients with KOA had statistically significant smaller normalized volumes of bilateral caudate nucleus and a trend toward smaller volume of the hippocampus as compared to the control subjects. Further investigations are necessary to characterize the role of caudate nucleus in the course of chronicity of pain associated with KOA.

Smaller Amygdala Volumes in Patients With Chronic Low Back Pain Compared With Healthy Control Individuals.

UNLABELLED: Although preclinical and clinical data strongly support an association between the amygdala and chronic pain by the presence of mood and cognitive disturbances in affected individuals, little attention has been paid to morphometric measurement of the structure in patients with chronic low back pain (CLBP). In the present study, magnetic resonance volumetric and surface analysis, using FMRIB's integrated registration and segmentation tool (FIRST), were performed to compare structural magnetic resonance imaging data obtained from 33 patients with CLBP with those obtained from 33 demographically similar healthy control individuals. Our results indicated that the normalized volumes of the left and right amygdala were significantly smaller in the CLBP group than in the control group. Detailed surface analyses further localized these differences. The degree of volume reduction was different between the left and right amygdala, with a greater involvement of the left side. Both groups exhibited similar significant hemispheric asymmetry for the amygdala (left > right). Similar asymmetry was suggested in the subgroup of 24 unmedicated patients. No significant correlations were found between amygdala volumes and pain characteristics or depressive symptoms. Our study provides in vivo imaging evidence of abnormal morphology of the amygdala in patients with CLBP using a fully automated segmentation method. PERSPECTIVE: Our study found that patients with CLBP had statistically significantly smaller normalized volumes of the bilateral amygdala, compared with healthy control individuals, with a greater involvement of the left side. These results may help to characterize the impaired affective-cognitive dimension in patients with chronic pain.

Radiographic findings of a well-differentiated sinonasal neuroendocrine neoplasm: Case report and review of the literature.

Typical carcinoid is a rare tumor among other neuroendocrine neoplasms that occur in the nasal cavity. Only a few cases of typical carcinoids in the nasal cavity have been reported. We report a case of typical carcinoid of the nasal cavity in a 61-year-old man who had a history of persistent nasal obstruction and epistaxis for approximately 17 years. Computed tomography revealed a huge, lobulated mass in the nasal cavity with extension into the posterior sphenoid sinus. Extensive bone destruction could be seen in the neighboring sphenoid sinus. MR imaging suggested that the tumor was close to the dura. The final histologic evaluation of the excised biopsy specimen yielded a diagnosis of a well-differentiated neuroendocrine neoplasm (typical carcinoid). In this article, the relevant reports in the literature are reviewed, and the role of radiographic findings on tumor diagnosis and on the establishment of a surgery plan is emphasized.

Decreased activation of cingulo-frontal-parietal cognitive/attention network during an attention-demanding task in patients with chronic low back pain.

INTRODUCTION: Attention deficits have been repeatedly reported via neuropsychological assessment in previous literature in patients with chronic low back pain (CLBP). However, there are few functional neuroimaging studies of patients with CLBP during attention processing, and the exact underlying neural mechanisms are yet to be elucidated. METHODS: We used functional magnetic resonance imaging (fMRI) to measure the function of the cingulo-frontal-parietal (CFP) cognitive/attention network while performing a multi-source interference task (MSIT) in patients with CLBP. Thirty-six patients with CLBP and 36 healthy controls were included in this study. The fMRI data were analyzed with the FSL-FEAT software. RESULTS: Our results indicated that patients with CLBP showed significantly less activation in the CFP network including the right dorsolateral prefrontal cortex, the dorsal anterior cingulate cortex, and bilateral superior parietal cortex during attention-demanding (MSITinterference > MSITcontrol) trials compared to the healthy controls. A significant negative correlation was found between the scores of the visual analog scale for pain and activation of the right prefrontal cortex during performing the MSIT in patients with CLBP. CONCLUSION: Our study provides in vivo imaging evidence of abnormal CFP network function during attention-demanding condition in patients with CLBP, which might reflect partly an adaptation/maladaptation of the brain to the chronic pain states.