| Objective: Migraine is an idiopathic headache disorder characterized by recurrent attacks of throbbing pain, often accompanied by nausea and vomiting, and before the attacks a few typical cases have an aura such as visual, sensory and motor dysfunction. Frequent migraine attacks may produce pain, pain sensitivity and productivity loss, and even increase the risk of subtle lesions in certain brain regions.Owing to technological improvements, brain imaging techniques have gained importance in the quest to understand migraine pathophysiology throughout the last ten years and specific emphasis has been placed on understanding neuronal activation in migraineurs using blood oxygenation level dependent functional magnetic resonance imaging(BOLD-f MRI). Rencently, advanced neuroimaging approaches have been employed to investigate structural and functional brain changes in migraineurs. Neuroimaging studies of migraineurs have showed functional abnormalities in brain regions associated with pain processing as a result of repeated headache attacks, including enhanced cortical excitability and altered pain modulatory systems. Despite the recent discoveries in basic neurosciences, migraine patho-physiology has not yet been completely understood.Migraine divides into two major subtypes: migraine with aura(MA) and migraine without aura(Mwo A). Indeed, functional imaging has investigated the underlying pathophysiology of the visual aura, indicating that cortical spreading depression(CSD) might represent its electrophysiological correlate in humans, whereas recent findings have found a dysfunctional cortical and subcortical pain processing network in Mwo A. However, few studies focus on the different pathophysiological mechanisms which can be distinguished relative to the two major subtypes of migraine.Resting-state analysis has been used to investigate the integration level of neural systems when no explicit task is engaged. It is worthwhile to note that different neuronal activities at the baseline state should be considered when explaining findings in the task-performing state. The changed features with regard to the resting state may serve as an adequate marker to reflect the progress of disease. The resting-state studies have been employed in several brain diseases, such as Alzheimer’s disease, Parkinson’s disease, schizophrenia and treatment-refractory depression and so on. However, until recently, few studies have evaluated the abnormalities of the resting state in migraineurs. Regional homogeneity(Re Ho) analysis is developed as a highly reliable data-driven method to analyze the synchronization of the BOLD signal among neighboring voxels of the brain during the resting state, and it might reflect the coherence of spontaneous neuronal activity. It has been proved to advance the understanding of the complexity of brain function and to complement the functional connectivity analysis during the resting state and task-related f MRI studies, and to serve as a valuable imaging feature for exploring pathological changes in brain function.The study aims to compare the interictal spontaneous brain activity between MA patients, Mwo A patients and control subjects in order to provided further insights into the complex migraine pathophysiology.Methods:Twenty-three eligible Mwo A patients and twelve MA patients and twenty-five gender-, age- and education- matched healthy volunteers participated in this study. After demographic and clinical characteristics were acquired, a 3.0-T MRI system was used to obtain resting-state f MRIs. Data preprocessing and processing was done by using a software called Data Processing Assistant for Resting-State(DPARSFA2.2). Re Ho method was applied to analyze the synchronization of the BOLD signal in the same time series among neighboring voxels of the brain. For the whole Mwo A group and MA group and healthy controls, a one-sample t-test was used to extract the Re Ho results across the subjects within each group to observe the default mode network(DMN). Then, a one-way anova analysis was performed to compare the differences among the three groups. Afterwards, a two-sample t-test was employed to compare the Re Ho results 1) between Mwo A and healthy controls, 2) between MA and healthy controls and 3) between Mwo A and MA. Finally, for the regions of interest in which Mwo A and MA patients showed abnormal resting-state properties compared with the healthy group, the Re Ho values of these regions were extracted, averaged and regressed against the duration of the migraine and the frequency of the attacks.Results:1 The results of the one-sample t-test showed that anterior cingulate cortex(ACC), posterior cingulate cortex(PCC), precuneus, inferior parietal lobe(IPL) and medial prefrontal cortex(MPFC) of the three groups which belonged to the default mode network exhibited significantly higher Re Ho values than each mean value of the whole brain regions during the resting state.2 The results of the one-way anova analysis revealed that the three groups showed not completely equal in Re Ho values in the right frontal lobe, left precuneus, left IPL, right putamen, right thalamus, right hippocampus, right occipital lobe, right cerebellum and brainstem(P<0.05 Alphasim corrected).3 The results of the two-sample t-test demonstrated that compared with healthy controls, Mwo A patients showed significant decreases in Re Ho values in the right thalamus, right putamen, right frontal lobe and right hippocampus(P <0.05 Alphasim corrected).4 The results revealed that MA patients showed a significant decrease in Re Ho values in the right thalamus, right putamen, right cerebellum and brainstem, whereas MA patients showed a significant increase in Re Ho values in the right occipital lobe compared with healthy controls(P<0.05 Alphasim corrected).5 Furthermore, compared with MA patients, increased Re Ho values in the right cerebellum and brainstem were shown in the Mwo A group(P<0.05 Alphasim corrected).6 The relationships between these resting-state properties and the average duration of the migraine and attack frequency were checked, but no results exceeded the threshold.Conclusions: Our results suggest that the resting-state abnormalities of these regions may be associated with functional impairments in pain processing in patients with migraine with and without aura. Specifically, the results of brain regions may reflect both the similarities and differences of pathophysiological mechanisms relative to two major subtypes of migraine. We hope that our results will improve understanding of migraine mechanisms. |
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