The success of stereoelectroencephalographic (SEEG) investigations depends crucially on the hypotheses on the putative location of the seizure onset zone. This information is derived from non-invasive data either based on visual analysis or advanced source localization algorithms. While source localization applied to interictal spikes recorded on scalp is the classical method, it does not provide unequivocal information regarding the seizure onset zone. Raw ictal activity contains a mixture of signals originating from several regions of the brain as well as EMG artifacts, hampering direct input to the source localization algorithms. We therefore introduce a methodology that disentangles the various sources contributing to the scalp ictal activity using independent component analysis and uses equivalent current dipole localization as putative locus of ictal sources. We validated the results of our analysis pipeline by performing long-term simultaneous scalp – intracerebral (SEEG) recordings in 14 patients and analyzing the wavelet coherence between the independent component encoding the ictal discharge and the SEEG signals in 8 patients passing the inclusion criteria. Our results show that invasively recorded ictal onset patterns, including low-voltage fast activity, can be captured by the independent component analysis of scalp EEG. The visibility of the ictal activity strongly depends on the depth of the sources. The equivalent current dipole localization can point to the seizure onset zone (SOZ) with an accuracy that can be as high as 10 mm for superficially located sources, that gradually decreases for deeper seizure generators, averaging at 47 mm in the 8 analyzed patients. Independent component analysis is therefore shown to have a promising SOZ localizing value, indicating whether the seizure onset zone is neocortical, and its approximate location, or located in mesial structures. That may contribute to a better crafting of the hypotheses used as basis of the stereo-EEG implantations.

立体脑电图 (SEEG) 研究的成功主要取决于对癫痫发作区假定位置的假设。该信息源自基于视觉分析或高级源定位算法的非侵入性数据。虽然应用于头皮上记录的发作间期尖峰的源定位是经典方法，但它不能提供有关癫痫发作区域的明确信息。原始发作活动包含源自大脑多个区域的信号以及肌电图伪影的混合信号，阻碍了对源定位算法的直接输入。因此，我们引入了一种方法，该方法使用独立成分分析来分解导致头皮发作活动的各种来源，并使用等效的电流偶极子定位作为假定的发作源轨迹。我们通过对 14 名患者进行长期同时头皮 - 脑内 (SEEG) 记录，并分析编码发作放电的独立分量与 8 名通过纳入标准的患者的 SEEG 信号之间的小波相干性，验证了我们的分析流程的结果。我们的结果表明，侵入性记录的发作模式，包括低电压快速活动，可以通过头皮脑电图的独立成分分析来捕获。发作活动的可见度很大程度上取决于源的深度。等效电流偶极子定位可以指向癫痫发作区 (SOZ)，对于表面定位的源，精度可高达 10 毫米，对于更深的癫痫发生器，精度逐渐降低，在 8 名分析的患者中平均为 47 毫米。 因此，独立成分分析显示出具有良好的 SOZ 定位价值，表明癫痫发作区是否是新皮质，及其大致位置，还是位于内侧结构。这可能有助于更好地制定用作立体脑电图植入基础的假设。