Scalp EEG is not a Blur: It Can See High Frequency Oscillations Although Their Generators are Small
Scalp EEG is not a Blur: It Can See High Frequency Oscillations Although Their Generators are Small
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DOI：
10.1007/s10548-013-0321-y
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发表时间：
2014-09-01
期刊：
影响因子：
2.7
通讯作者：
Jacobs, J.
中科院分区：
文献类型：
--
作者：
Zelmann, R.;Lina, J. M.;Jacobs, J.
高频振荡（HFO）正在成为致癫痫性的生物标志物。它们已被证明起源于较小的大脑区域。令人惊讶的是，可以从头皮记录自发的 HFO。为了了解如何观察头皮上的这些小事件，一种途径是分析头皮 HFO 时的皮质相关物。通过同时记录 11 名患者的头皮和颅内记录，我们研究了头皮事件在皮质表面的空间分布。对于典型的发作间期癫痫样放电，硬膜下分布如预期的那样在空间上延伸。相反，对于头皮 HFO，硬膜下图对应于焦点源，由一个或几个小的空间范围激活组成。这些地形表明，头皮上可见的 HFO 是由小皮质区域产生的。相似的头皮分布对应于标准 1 cm 硬膜下网格上的不同分布，对相似的头皮 HFO 进行平均可以得到局灶性硬膜下图。硬膜下网格“看到”所有有助于附近头皮接触潜力的假设对于 HFO 来说是无效的。结果表明，在标准头皮和网格电极间距离的情况下，这些小范围事件在空间上采样不足。高密度头皮电极分布似乎有必要获得头皮上 HFO 的固体样本。更好地了解空间采样对头皮上高频大脑活动观察的影响对于其作为癫痫生物标志物的临床应用非常重要。
High frequency oscillations (HFOs) are emerging as biomarkers of epileptogenicity. They have been shown to originate from small brain regions. Surprisingly, spontaneous HFOs can be recorded from the scalp. To understand how is it possible to observe these small events on the scalp, one avenue is the analysis of the cortical correlates at the time of scalp HFOs. Using simultaneous scalp and intracranial recordings of 11 patients, we studied the spatial distribution of scalp events on the cortical surface. For typical interictal epileptiform discharges the subdural distributions were, as expected, spatially extended. On the contrary, for scalp HFOs the subdural maps corresponded to focal sources, consisting of one or a few small spatial extent activations. These topographies suggest that small cortical areas generated the HFOs seen on the scalp. Similar scalp distributions corresponded to distinct distributions on a standard 1 cm subdural grid and averaging similar scalp HFOs resulted in focal subdural maps. The assumption that a subdural grid "sees" everything that contributes to the potential of nearby scalp contacts was not valid for HFOs. The results suggest that these small extent events are spatially undersampled with standard scalp and grid inter-electrode distances. High-density scalp electrode distributions seem necessary to obtain a solid sampling of HFOs on the scalp. A better understanding of the influence of spatial sampling on the observation of high frequency brain activity on the scalp is important for their clinical use as biomarkers of epilepsy.