Study On Application Of Multimodel Neuroimaging In Idiopathic Gereralized Epilepsy

Epilepsy is a chronic neurologic condition characterized by recurrent unprovoked seizures, which caused by the excessive, synchronized and disorderly discharges of a set of cerebral neurons. Hence, it is of great importance to study the mechanism of epilepsy from both micro level and macro level. In the current study, we focus on the neural mass level action in epilepsy with a new emerging non-invasive technique, i.e., multimodel neuroimagings including simultaneous electroenphalogram and functional magnetic resonance imaging (EEG-fMRI), diffusion tensor imaging (DTI)as well as high resolution anatomical MRI. Using these methods, the brain mechanism of idiopathic generalized epilepsy (IGE) was studied, achieving three lines of breakthroughs: method of epileptic focus localization, features of functional network and variation of structural parameters.1, We developed a new scheme based on simultaneous EEG-fMRI to promote the detectability of epileptic focus. With this new scheme, we classified interictal epileptic discharge (IED) by a combination of an independent component analysis (ICA) and a temporal correlation analysis. The discharge information after classification of IED was used for blood oxygenation-level-dependent (BOLD) imaging. The proposed scheme was effective to identify the regions of BOLD action consistent with clinico-electron localization, where no BOLD change related to IED was found by routine method in patients with complex epileptic discharges. Therefore, the scheme was of clinical meaning in providing more detailed information of the foci.2, Using the resting-state fMRI, a set of important functional networks in IGE were analyzed in-depth, including cortico-thalamus network, basal ganglia network (BGN) and default mode network (DMN), which were related to the generation and propagation of SWDs or influence of brain resting function by SWDs. Because SWDs might affect these functional networks, the simultaneous EEG during fMRI acquisition was recorded to classify whether the BOLD signal was hybrided by SWDs or not. For the cortico-thalamus network, which was important to the generation and propagation of SWDs, the functional connectivity between thalamus and anterior cingulated cortex (ACC) was significantly decreased in IGE with absence seizures during the non-discharge period (NDP). This finding, avoided effects from SWDs, might reflect a permanent abnormality between thalamus and ACC in IGE. The abnormality might play important role in the generation and propagation of SWDs in IGE. For the BGN, the functional connectivity of BGN in IGE patients demonstrated more integration within the network during NDP and WDP (the period with discharge). Furthermore, it increased more evidently during WDP compared with that in NDP, and it showed a positive relationship with the number of SWDs in WDP. These findings provided an evidence confirming the role of the BGN as an important modulator of SWDs in IGE. For the DMN, the decreased functional connectivity within DMN in IGE patients with absence seizures was found during NDP. These results indicated abnormal functional integration in DMN, which was derived from anatomic abnormality or functional reorganization. Such changes could lead to the cognitive mental impairment and unconsciousness during absence seizure. These findings on the three networks suggested that IGE could result in complex impairment of brain function, namely, decreased connectivity in the cortex and increased connectivity within subcortical nuclei. Such findings also supported that the abnormality of brain function in IGE presented a characteristic of decentralization.3, Based on the brain structural imagings (DTI and high resolution anatomical MRI), the diffusion properties and volume of subcortical nuclei, were evaluated in IGE patients with absence seizure. Abnormality in both of them was found, which provide preliminary evidence demonstrating microstructural changes of subcortical structures related to the chronic abnormal epileptic activity. It also found to be more severe in patients with early age of onset than those with later age of onset. This structural disturbance provided anatomical evidence for the functional network and derived presumption that thalamus and basal ganglia were involved in propagation and modulation of SWDs in IGE. These consistant alterations from anatomical and functional abnormality might be a characteristic for IGE patients with absence seizures, which deserves further study in clinical application.