Rummel Christian, Abela Eugenio, Andrzejak Ralph G, Hauf Martinus, Pollo Claudio, Müller Markus, Weisstanner Christian, Wiest Roland, Schindler Kaspar
Support Center for Advanced Neuroimaging (SCAN), University Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern, Switzerland.
Support Center for Advanced Neuroimaging (SCAN), University Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern, Switzerland; Department of Neurology, Inselspital, Bern, Switzerland.
PLoS One. 2015 Oct 29;10(10):e0141023. doi: 10.1371/journal.pone.0141023. eCollection 2015.
Epilepsy surgery is a potentially curative treatment option for pharmacoresistent patients. If non-invasive methods alone do not allow to delineate the epileptogenic brain areas the surgical candidates undergo long-term monitoring with intracranial EEG. Visual EEG analysis is then used to identify the seizure onset zone for targeted resection as a standard procedure.
Despite of its great potential to assess the epileptogenicty of brain tissue, quantitative EEG analysis has not yet found its way into routine clinical practice. To demonstrate that quantitative EEG may yield clinically highly relevant information we retrospectively investigated how post-operative seizure control is associated with four selected EEG measures evaluated in the resected brain tissue and the seizure onset zone. Importantly, the exact spatial location of the intracranial electrodes was determined by coregistration of pre-operative MRI and post-implantation CT and coregistration with post-resection MRI was used to delineate the extent of tissue resection. Using data-driven thresholding, quantitative EEG results were separated into normally contributing and salient channels.
In patients with favorable post-surgical seizure control a significantly larger fraction of salient channels in three of the four quantitative EEG measures was resected than in patients with unfavorable outcome in terms of seizure control (median over the whole peri-ictal recordings). The same statistics revealed no association with post-operative seizure control when EEG channels contributing to the seizure onset zone were studied.
We conclude that quantitative EEG measures provide clinically relevant and objective markers of target tissue, which may be used to optimize epilepsy surgery. The finding that differentiation between favorable and unfavorable outcome was better for the fraction of salient values in the resected brain tissue than in the seizure onset zone is consistent with growing evidence that spatially extended networks might be more relevant for seizure generation, evolution and termination than a single highly localized brain region (i.e. a "focus") where seizures start.
癫痫手术是药物难治性患者一种潜在的治愈性治疗选择。如果仅靠非侵入性方法无法确定致痫脑区，手术候选者需接受颅内脑电图的长期监测。然后，视觉脑电图分析作为标准程序用于识别癫痫发作起始区，以进行靶向切除。
尽管定量脑电图分析在评估脑组织致痫性方面有很大潜力，但尚未进入常规临床实践。为证明定量脑电图可产生具有高度临床相关性的信息，我们回顾性研究了术后癫痫控制与在切除的脑组织和癫痫发作起始区评估的四种选定脑电图指标之间的关联。重要的是，通过术前磁共振成像（MRI）与植入后计算机断层扫描（CT）的配准确定颅内电极的确切空间位置，并使用与切除后MRI的配准来描绘组织切除范围。使用数据驱动的阈值化方法，将定量脑电图结果分为正常贡献通道和显著通道。
在术后癫痫控制良好的患者中，与癫痫控制效果不佳的患者相比（整个发作期记录的中位数），在四种定量脑电图指标中的三种指标中，显著通道的切除比例明显更高。当研究对癫痫发作起始区有贡献的脑电图通道时，相同的统计分析显示与术后癫痫控制无关联。
我们得出结论，定量脑电图指标提供了与临床相关的目标组织客观标志物，可用于优化癫痫手术。切除的脑组织中显著值比例在区分良好和不良结果方面比癫痫发作起始区更好，这一发现与越来越多的证据一致，即空间扩展网络可能比癫痫发作起始的单个高度局限脑区（即“病灶”）在癫痫发作的产生、演变和终止中更相关。
