Montreal Neurological Institute and Hospital, McGill University, Montreal, Canada.
Department of Neurosurgery, Osaka University Graduate School of Medicine, Suita, Japan.
Ann Neurol. 2017 Jul;82(1):57-66. doi: 10.1002/ana.24973.
Structural and functional imaging studies in focal epilepsy often reveal distributed regions of abnormality. These are interpreted as representing the existence of epileptic networks, but the presence of actual neuronal interactions between these regions has not been demonstrated. We sought to determine whether the distributed hemodynamic responses often seen in functional magnetic resonance imaging (fMRI) studies of scalp interictal epileptic discharges (IEDs) actually correspond to synchronized neuronal activities when examining the intracerebral electroencephalogram (iEEG) at distant nodes of the network.
We studied 28 patients who underwent first EEG-fMRI and then iEEG, and had significant hemodynamic responses in the gray matter. We coregistered the hemodynamic responses to the iEEG electrode contact positions and analyzed synchrony, measured by correlation, between IEDs recorded by iEEG in regions with and without hemodynamic responses.
The synchrony of intracerebral IED activity between pairs of regions showing a hemodynamic response was higher compared to that between pairs of regions without (p < 0.0001) and between pairs of regions, one with and one without hemodynamic response (p < 0.0001). These differences were found during the interictal periods with IEDs but were absent during the interictal periods without IEDs. Higher synchrony was also observed between regions involved at seizure onset (p < 0.0001).
EEG-fMRI studies are unique in their ability to reveal hemodynamic concomitants of IEDs anywhere in the brain. This study proves that iEEG activity is synchronized between these regions of hemodynamic response, thus demonstrating the existence of an actual neuronally based interictal epileptic network. This also validates the EEG-fMRI approach to reveal this network noninvasively. Ann Neurol 2017;82:57-66.
在局灶性癫痫的结构性和功能性成像研究中，经常发现异常的分布区域。这些被解释为代表癫痫网络的存在，但尚未证明这些区域之间存在实际的神经元相互作用。我们试图确定在检查网络的远节点的颅内脑电图（iEEG）时，在头皮发作间期癫痫放电（IED）的功能磁共振成像（fMRI）研究中经常看到的分布式血液动力学反应是否实际上对应于同步神经元活动。
我们研究了 28 例患者，这些患者首先进行了 EEG-fMRI 检查，然后进行了 iEEG 检查，并且在灰质中有明显的血液动力学反应。我们将血液动力学反应与 iEEG 电极接触位置配准，并分析了在有和没有血液动力学反应的区域中记录的 IED 之间通过相关性测量的同步性。
在显示血液动力学反应的区域之间，颅内 IED 活动的同步性比没有血液动力学反应的区域（p<0.0001）和有和没有血液动力学反应的区域之间（p<0.0001）之间更高。这些差异是在有 IED 的发作间期期间发现的，但在没有 IED 的发作间期期间不存在。在发作起始时涉及的区域之间也观察到更高的同步性（p<0.0001）。
EEG-fMRI 研究具有独特的能力，可以揭示大脑中任何地方 IED 的血液动力学伴随物。这项研究证明了这些血液动力学反应区域之间的 iEEG 活动是同步的，从而证明了存在实际的基于神经元的发作间期癫痫网络。这也验证了 EEG-fMRI 方法可以无创性地揭示这种网络。神经病学年鉴 2017；82：57-66。
