Magnetoencephalography Reveals a Widespread Increase in Network Connectivity in Idiopathic/Genetic Generalized Epilepsy

Idiopathic/genetic generalized epilepsy (IGE/GGE) is characterized by seizures, which start and rapidly engage widely distributed networks, and result in symptoms such as absences, generalized myoclonic and primary generalized tonic-clonic seizures. Although routine magnetic resonance imaging is apparently normal, many studies have reported structural alterations in IGE/GGE patients using diffusion tensor imaging and voxel-based morphometry. Changes have also been reported in functional networks during generalized spike wave discharges. However, network function in the resting-state without epileptiforme discharges has been less well studied. We hypothesize that resting-state networks are more representative of the underlying pathophysiology and abnormal network synchrony. We studied functional network connectivity derived from whole-brain magnetoencephalography recordings in thirteen IGE/GGE and nineteen healthy controls. Using graph theoretical network analysis, we found a widespread increase in connectivity in patients compared to controls. These changes were most pronounced in the motor network, the mesio-frontal and temporal cortex. We did not, however, find any significant difference between the normalized clustering coefficients, indicating preserved gross network architecture. Our findings suggest that increased resting state connectivity could be an important factor for seizure spread and/or generation in IGE/GGE, and could serve as a biomarker for the disease.特发性/遗传性全面性癫痫（idiopathic/genetic generalized epilepsy, IGE/GGE）以发作为特征，发作起始后快速累及广泛分布的脑网络，并引发失神发作、全面性肌阵挛发作及原发性全面性强直-阵挛发作等症状。尽管常规磁共振成像（magnetic resonance imaging）通常表现正常，但诸多研究通过弥散张量成像（diffusion tensor imaging）与基于体素的形态测量学（voxel-based morphometry），在IGE/GGE患者中发现了脑结构改变。全面性棘慢波放电期间的脑功能网络改变亦已有报道，但针对无痫样放电的静息态脑网络功能的研究尚少。本研究假设静息态脑网络更能反映疾病潜在的病理生理学机制及异常的网络同步性。本研究纳入13例IGE/GGE患者与19例健康对照者，对其全脑脑磁图（magnetoencephalography）记录的功能网络连接性进行分析。采用图论网络分析（graph theoretical network analysis）方法后发现，与健康对照相比，患者组的脑连接呈广泛性增强，该改变在运动网络、内侧额叶及颞叶皮层最为显著。但两组的标准化聚类系数（normalized clustering coefficient）未见显著差异，提示整体网络结构得以保留。本研究结果表明，静息态脑连接增强可能是IGE/GGE患者癫痫发作扩散和/或产生的重要潜在机制，同时可作为该疾病的生物标志物。