Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada.
Epilepsia. 2011 Mar;52(3):515-22. doi: 10.1111/j.1528-1167.2010.02938.x. Epub 2011 Jan 26.
Idiopathic generalized epilepsy (IGE) is characterized by electroencephalography (EEG) recordings with generalized spike wave discharges (GSWDs) arising from normal background activity. Although GSWDs are the result of highly synchronized activity in the thalamocortical network, EEG without GSWDs is believed to represent normal brain activity. The aim of this study was to investigate whether thalamocortical interactions are altered even during GSWD-free EEG periods in patients with IGE.
A GSWD-related group analysis was performed in 12 IGE patients to define seeds in areas involved during GSWDs. EEG-functional magnetic resonance imaging (fMRI) datasets from 22 IGE patients without GSWDs during the investigation and 30 age-matched healthy controls were then selected to investigate functional connectivity in GSWD-related areas. Blood oxygen level dependent (BOLD) signal changes were extracted from seeds defined by the GSWD-related group analysis. The averaged time course within each seed was used to detect brain regions with BOLD signal correlated with the seed. Group differences between patients and controls were estimated.
The GSWD-related group analysis showed BOLD activation in the thalamus, the frontomesial cortex, and the cerebellum and BOLD deactivation in default mode areas. For the connectivity analysis, eight seeds were placed bilaterally in the thalamus, mesial frontal cortex, precuneus, and cerebellum. The functional connectivity analysis of these seeds did not show clearly altered functional connectivity for patients versus controls.
The results underscore the paroxysmal nature of GSWDs: Although GSWDs are characterized by highly synchronized activity in the thalamocortical network, the functional connectivity in areas involved during GSWDs does not demonstrate abnormality in GSWD-free periods.
特发性全面性癫痫（IGE）的特征是脑电图（EEG）记录显示出源于正常背景活动的全身性棘慢波放电（GSWDs）。尽管 GSWDs 是丘脑皮质网络中高度同步活动的结果，但没有 GSWDs 的 EEG 被认为代表正常的大脑活动。本研究的目的是调查 IGE 患者即使在无 GSWD 的 EEG 期间，丘脑皮质相互作用是否发生改变。
对 12 例 IGE 患者进行了 GSWD 相关组分析，以确定在 GSWD 期间涉及的区域中的种子。然后从 22 例在研究期间无 GSWD 的 IGE 患者和 30 名年龄匹配的健康对照者中选择 EEG-功能磁共振成像（fMRI）数据集，以研究 GSWD 相关区域的功能连接。从 GSWD 相关组分析中定义的种子中提取血氧水平依赖（BOLD）信号变化。使用每个种子内的平均时程来检测与种子相关的 BOLD 信号相关的脑区。估计患者与对照组之间的组间差异。
GSWD 相关组分析显示在丘脑、额内侧皮质和小脑中出现 BOLD 激活，而在默认模式区域中出现 BOLD 去激活。对于连接分析，在丘脑、额内侧皮质、楔前叶和小脑双侧放置了八个种子。这些种子的功能连接分析未显示出患者与对照组之间功能连接的明显改变。
这些结果强调了 GSWD 的阵发性特征：尽管 GSWD 以丘脑皮质网络中的高度同步活动为特征，但在 GSWD 期间涉及的区域中的功能连接在无 GSWD 期间并未显示异常。
