Presurgical Epilepsy Evaluation Unit and Functional Brain Mapping Laboratory, Neurology Department, University Hospital, University of Geneva, 1 Geneva, Switzerland.
Brain. 2011 Oct;134(Pt 10):2867-86. doi: 10.1093/brain/awr156. Epub 2011 Jul 12.
In patients with medically refractory focal epilepsy who are candidates for epilepsy surgery, concordant non-invasive neuroimaging data are useful to guide invasive electroencephalographic recordings or surgical resection. Simultaneous electroencephalography and functional magnetic resonance imaging recordings can reveal regions of haemodynamic fluctuations related to epileptic activity and help localize its generators. However, many of these studies (40-70%) remain inconclusive, principally due to the absence of interictal epileptiform discharges during simultaneous recordings, or lack of haemodynamic changes correlated to interictal epileptiform discharges. We investigated whether the presence of epilepsy-specific voltage maps on scalp electroencephalography correlated with haemodynamic changes and could help localize the epileptic focus. In 23 patients with focal epilepsy, we built epilepsy-specific electroencephalographic voltage maps using averaged interictal epileptiform discharges recorded during long-term clinical monitoring outside the scanner and computed the correlation of this map with the electroencephalographic recordings in the scanner for each time frame. The time course of this correlation coefficient was used as a regressor for functional magnetic resonance imaging analysis to map haemodynamic changes related to these epilepsy-specific maps (topography-related haemodynamic changes). The method was first validated in five patients with significant haemodynamic changes correlated to interictal epileptiform discharges on conventional analysis. We then applied the method to 18 patients who had inconclusive simultaneous electroencephalography and functional magnetic resonance imaging studies due to the absence of interictal epileptiform discharges or absence of significant correlated haemodynamic changes. The concordance of the results with subsequent intracranial electroencephalography and/or resection area in patients who were seizure free after surgery was assessed. In the validation group, haemodynamic changes correlated to voltage maps were similar to those obtained with conventional analysis in 5/5 patients. In 14/18 patients (78%) with previously inconclusive studies, scalp maps related to epileptic activity had haemodynamic correlates even when no interictal epileptiform discharges were detected during simultaneous recordings. Haemodynamic changes correlated to voltage maps were spatially concordant with intracranial electroencephalography or with the resection area. We found better concordance in patients with lateral temporal and extratemporal neocortical epilepsy compared to medial/polar temporal lobe epilepsy, probably due to the fact that electroencephalographic voltage maps specific to lateral temporal and extratemporal epileptic activity are more dissimilar to maps of physiological activity. Our approach significantly increases the yield of simultaneous electroencephalography and functional magnetic resonance imaging to localize the epileptic focus non-invasively, allowing better targeting for surgical resection or implantation of intracranial electrode arrays.
在适合癫痫手术的药物难治性局灶性癫痫患者中，一致的非侵入性神经影像学数据有助于指导侵入性脑电图记录或手术切除。同时进行脑电图和功能磁共振成像记录可以揭示与癫痫活动相关的血流动力学波动区域，并有助于定位其发生器。然而，这些研究中的许多（40-70%）仍然没有定论，主要是因为在同时记录期间没有发作间期癫痫样放电，或者缺乏与发作间期癫痫样放电相关的血流动力学变化。我们研究了头皮脑电图上存在癫痫特异性电压图是否与血流动力学变化相关，并有助于定位癫痫灶。在 23 例局灶性癫痫患者中，我们使用在扫描仪外的长期临床监测中记录的平均发作间期癫痫样放电来构建癫痫特异性脑电图电压图，并计算该图与扫描仪中每个时间帧的脑电图记录之间的相关性。该相关系数的时间过程被用作功能磁共振成像分析的回归量，以映射与这些癫痫特异性图相关的血流动力学变化（与地形图相关的血流动力学变化）。该方法首先在 5 例常规分析显示与发作间期癫痫样放电相关的显著血流动力学变化的患者中进行了验证。然后，我们将该方法应用于 18 例因同时进行的脑电图和功能磁共振成像研究中缺乏发作间期癫痫样放电或缺乏显著相关血流动力学变化而无定论的患者。评估了手术后无癫痫发作的患者颅内脑电图和/或切除区域与结果的一致性。在验证组中，与电压图相关的血流动力学变化在 5/5 例患者中与常规分析获得的变化相似。在之前无定论的 18 例患者中的 14 例（78%）中，即使在同时记录期间未检测到发作间期癫痫样放电，与癫痫活动相关的头皮图也存在血流动力学相关性。与电压图相关的血流动力学变化在空间上与颅内脑电图或切除区域一致。与内侧/极叶颞叶癫痫相比，我们在外侧颞叶和颞外新皮层癫痫患者中发现了更好的一致性，这可能是因为与外侧颞叶和颞外癫痫活动相关的脑电图电压图与生理活动的图更不相似。我们的方法显著提高了同时进行脑电图和功能磁共振成像以非侵入性方式定位癫痫灶的效果，从而更好地针对手术切除或颅内电极阵列植入进行定位。
