ObjectiveTo reveal impairments in the perceptual networks in tuberous sclerosis complex (TSC) with epilepsy by functional connectivity MRI (fcMRI). MethodsThe fcMRI-based independent component analysis (ICA) was used to measure the resting state functional connectivity in nine TSC patients with epilepsy recruited from June 2010 to June 2012 and perceptual networks including the sensorimotor network (SMN), visual network (VN), and auditory network (AN) were investigated. The correlation between Z values in regions of interest (ROIs) and age of seizure onset or duration of epilepsy were analyzed. ResultsCompared with the controls, the TSC patients with epilepsy presented decreased functional connectivity in primary visual cortex within the VN networks and there were no increased connectivity. Increased connectivity in left middle temporal gyrus and inferior temporal gyrus was found and decreased connectivity was detected in right inferior frontal gyrus within AN networks. Decreased connectivity was detected at the right inferior frontal gyrus and the increase in connectivity was found in right thalamus within SMN netwoks. No significant correlations were found between Z values in ROIs including the primary visual cortex within the VN, right thalamus and inferior frontal gyrus within SMN, left temporal lobe and right inferior frontal gyrus within AN and the duration of the disease or the age of onset. ConclusionFhere is altered (both increased and decreased) functional connectivity in the perceptual networks of TSC patients with epilepsy. The decreased functional connectivity may reflect the dysfunction of correlative perceptual networks in TSC patients, and the increased functional connectivity may indicate the compensatory mechanism or reorganization of cortical networks. Our fcMRI study may contribute to the understanding of neuropathophysiological mechanisms underlying perceptual impairments in TSC patients with epilepsy.
ObjectiveSeizure-related respiratory or cardiac dysfunction was once thought to be the direct cause of sudden unexpected death in epilepsy (SUDEP), but both may be secondary to postictal cerebral inhibition. An important issue that has not been explored to date is the neural network basis of cerebral inhibition. Our aim was to investigate the features of neural networks in patients at high risk for SUDEP using a blood oxygen level-dependent (BOLD) resting-state functional MRI (Rs-fMRI) technique. MethodsRs-fMRI data were recorded from 13 patients at high risk for SUDEP and 12 patients at low risk for SUDEP. The amplitude of low-frequency fluctuations (ALFF) values were compared between the two groups to decipt the regional brain activities. ResultsCompared with patients at low risk for SUDEP, patients at high risk exhibited significant ALFF reductions in the right superior frontal gyrus, the left superior orbital frontal gyrus, the left insula and the left thalamus; and ALFF increase in the right middle cigulum gyrus, the right supplementary motor area and the left thalamus. ConclusionsThese findings highlight the need to understand the fundamental neural network dysfunction in SUDEP, which may fill the missing link between seizure-related cardiorespiratory dysfunction and SUDEP, and provide a promising neuroimaging biomarker for risk prediction of SUDEP.
Objective The ReHo, ALFF, fALFF of resting-state functional magnetic resonance imaging (RS-fMRI) technology were used to study the influencing factors and neural mechanism of cognitive dysfunction in patients with benign epilepsy of childhood with centrotemporal spikes (BECT). Methods Fourteen patients were enrolled (from April 2015 to March 2018) from epilepsy specialist outpatients and Functional Department of Neurosurgery of Tianjin Medical University General Hospital. They underwent the long term VEEG monitoring (one sleep cycle was included at least), the Wechsler Intelligence Scale (China Revised), the head MRI and RS-fMRI examinations. Spike-wave index (SWI), FIQ, VIQ, PIQ scores were calculated. According to full-scale IQ (FIQ), they were divided into two groups: FIQ<90 (scores range from 70 to 89, the average score was 78.3±8.9, 6 cases) and FIQ≥90 (scores range from 90 to 126, the average score was 116.6±12.9, 8 cases). SPSS21.0 statistical software was used to compare the general clinical data and SWI of the two groups, and the correlation between clinical factors and the evaluation results of Wechsler Intelligence Scale was analyzed. The RS-fMRI images were preprocessed and the further data were analysed by two independent samplest-test under the whole brain of regional homogeneity (ReHo), amplitude of low frequency fluctuation (ALFF) and fractional of ALFF (fALFF) methods. The differences of brain activation regions in RS-fMRI between the two groups were observed, and the results of general clinical data, SWI and cognitive function test were compared and analyzed comprehensively. Results The differences of SWI were statistically significant (P<0.05): FIQ<90 group were greater than FIQ≥90 group. The FIQ, VIQ and PIQ of two groups were negatively correlated with SWI (P<0.05). And the FIQ and PIQ were negatively correlated with the total number of seizures (P<0.05). Compared with FIQ≥90 group by two samplet-test based on whole level ReHo, ALFF, fALFF methods, deactivation of brain regions of FIQ<90 group include bilateral precuneus, posterior cingulate and occipital lobe, and enhanced activation of brain regions include left prefrontal cortex, bilateral superior frontal gyrus medial and right precentral gyrus, supplementary motor area, angular gyrus, supramarginal gyrus, middle temporal gyrus, bilateral insular lobe and subcortical gray matter structures. Conclusions Frequent epileptic discharges during slow wave sleep and recurrent clinical episodes were risk factors for cognitive impairment in BECT patients. Repeated clinical seizures and frequent subclinical discharges could cause dysfunction of local brain areas associated with cognition and the default network, resulting in patients with impaired cognitive function.
Nowadays, an increasing number of researches have shown that epilepsy, as a kind of neural network disease, not only affects the brain region of seizure onset, but also remote regions at which the brain network structures are damaged or dysfunctional. These changes are associated with abnormal network of epilepsy. Resting-state network is closely related to human cognitive function and plays an important role in cognitive process. Cognitive dysfunction, a common comorbidity of epilepsy, has adverse impacts on life quality of patients with epilepsy. The mechanism of cognitive dysfunction in epileptic patients is still incomprehensible, but the change of resting-state brain network may be associated with their cognitive impairment. In order to further understand the changes of resting-state network associated with the cognitive function and explore the brain network mechanism of the occurrence of cognitive dysfunction in patients with epilepsy, we review the related researches in recent years.
Objective To identify the most consistent and replicable characteristics of altered spontaneous brain activity in mesial temporal lobe epilepsy patients with unilateral hippocampal sclerosis (MTLE-HS). Methods A systematic literature search was performed in PubMed, Embase, The Cochrane Library, China National Knowledge Infrastructure, Wanfang, and CQVIP databases, to identify eligible whole-brain resting state functional magnetic resonance imaging studies that had measured differences in amplitude of low-frequency fluctuations or fractional amplitude of low-frequency fluctuations between patients with MTLE-HS and healthy controls from January 2000 to January 2019. After literature screening and data extraction, Anisotropic Effect-Size Signed Differential Mapping software was used for voxel based pooled meta-analysis. Results Nine datasets from six studies were finally included, which contained 207 MTLE-HS patients and 239 healthy controls. The results demonstrated that, compared with the healthy controls, the MTLE-HS patients showed increased spontaneous brain activity in right hippocampus and parahippocampal gyrus, right superior temporal gyrus, left cingulate gyrus, right fusiform gyrus, and right inferior temporal gyrus; while decreased spontaneous brain activity in left superior frontal gyrus, right angular gyrus, right middle frontal gyrus, left inferior parietal lobule, left precuneus, and right cerebellum (P<0.005, cluster extent≥10). Conclusion The current meta-analysis demonstrates that patients with MTLE-HS show increased spontaneous brain activity in lateral and mesial temporal regions and decreased spontaneous brain activity in default mode network, which preliminarily clarifies the characteristics of altered spontaneous brain activity in patients with MTLE-HS.
White matter lesion (WML) of presumed vascular origin is one of the common imaging manifestations of cerebral small vessel diseases, which is the main reason of cognitive impairment and even vascular dementia in the elderly. However, there is a lack of early and effective diagnostic methods currently. In recent years, studies of diffusion tensor imaging (DTI) and resting-state functional magnetic resonance imaging (rs-fMRI) have shown that cognitive impairment in patients with WMLs is associated with disrupted white matter microstructural and brain network connectivity. Therefore, it’s speculated that DTI and rs-fMRI can be effective in early imaging diagnosis of WMLs-related cognitive impairment. This article reviews the role and significance of DTI and rs-fMRI in WMLs-related cognitive impairment.
Amblyopia is a visual development deficit caused by abnormal visual experience in early life, mainly manifesting as defected visual acuity and binocular visual impairment, which is considered to reflect abnormal development of the brain rather than organic lesions of the eye. Previous studies have reported abnormal spontaneous brain activity in patients with amblyopia. However, the location of abnormal spontaneous activity in patients with amblyopia and the association between abnormal brain function activity and clinical deficits remain unclear. The purpose of this study is to analyze spontaneous brain functional activity abnormalities in patients with amblyopia and their associations with clinical defects using resting-state functional magnetic resonance imaging (fMRI) data. In this study, 31 patients with amblyopia and 31 healthy controls were enrolled for resting-state fMRI scanning. The results showed that spontaneous activity in the right angular gyrus, left posterior cerebellum, and left cingulate gyrus were significantly lower in patients with amblyopia than in controls, and spontaneous activity in the right middle temporal gyrus was significantly higher in patients with amblyopia. In addition, the spontaneous activity of the left cerebellum in patients with amblyopia was negatively associated with the best-corrected visual acuity of the amblyopic eye, and the spontaneous activity of the right middle temporal gyrus was positively associated with the stereoacuity. This study found that adult patients with amblyopia showed abnormal spontaneous activity in the angular gyrus, cerebellum, middle temporal gyrus, and cingulate gyrus. Furthermore, the functional abnormalities in the cerebellum and middle temporal gyrus may be associated with visual acuity defects and stereopsis deficiency in patients with amblyopia. These findings help explain the neural mechanism of amblyopia, thus promoting the improvement of the treatment strategy for amblyopia.
Electroconvulsive therapy (ECT) is an interventional technique capable of highly effective neuromodulation in major depressive disorder (MDD), but its antidepressant mechanism remains unclear. By recording the resting-state electroencephalogram (RS-EEG) of 19 MDD patients before and after ECT, we analyzed the modulation effect of ECT on the resting-state brain functional network of MDD patients from multiple perspectives: estimating spontaneous EEG activity power spectral density (PSD) using Welch algorithm; constructing brain functional network based on imaginary part coherence (iCoh) and calculate functional connectivity; using minimum spanning tree theory to explore the topological characteristics of brain functional network. The results show that PSD, functional connectivity, and topology in multiple frequency bands were significantly changed after ECT in MDD patients. The results of this study reveal that ECT changes the brain activity of MDD patients, which provides an important reference in the clinical treatment and mechanism analysis of MDD.