失神性癫痫的动态功能MRI研究

Dynamic functional MRI study of absence seizures

目的采用动态分析的功能MRI(fMRI)技术,观察失神性癫痫发生过程中脑区活动改变的特征。材料与方法 12例儿童失神性癫痫患者参与了研究。采用同步脑电图(EEG)-fMRI技术,采集17次全面棘慢波癫痫发放的fMRI数据。采用基于序列血流动态反应函数的广义线性模型分析技术及时间序列分析技术,观察失神性发作时癫痫全面性棘慢波发放引起的脑区动态改变过程。结果丘脑以及包括默认网络在内广泛的皮层区域在癫痫发作时有显著的信号改变;在癫痫发作前18s丘脑与皮层即有信号的改变,并且随时间进程,BOLD信号的相位发生逐渐翻转改变;发作后丘脑的最大激活与皮层的最大负激活出现时间点不同。结论丘脑活动与失神性癫痫的发作有关,而默认网络及外侧额叶等广泛脑区的负激活与癫痫发作意识损害等功能抑制有关;不同的脑区在癫痫发放过程中受到影响的时间不同;促进了对失神性癫痫发作时意识受损的病理生理机制的理解。

Objective： To study the dynamic activation during the progress of absence seizures using dynamic blood oxygenation level-dependent functional MRI （BOLD-fMRI） analysis. Materials and Methods： Seventeen sessions of simultaneous EEG and tMRI data were acquired from 12 children with absence seizures （AS）. Sequential hemodynamic-response function based generalized linear model analysis and region-of-interest based time-course analysis were employed to investigate dynamic alterations of brain region during procedure of absence seizures. Results： The thalamus and widely distributed cortical structures were found to have significant BOLD alterations responding to the generalized-slow and wave discharges. BOLD response was found in the thalamus and cortex 18 seconds prior to generalized-slow and wave discharges. There were variable time points of maximal activation or deactivation in different brain regions. Conclusions： The thalamus activation is proposed to be linked to the generation of epileptic seizures, and the deactivation in the default-mode regions and the other wide cortical regions may be correlated with the consciousness impairments in seizures. This study contributed to the understanding of mechanism of impaired consciousness in AS. The finding of BOLD response prior to the GSWD supports the feasibility of seizure prediction.