Electrical Geodesics, Inc. Eugene, OR, USA.
Front Neurol. 2013 May 15;4:55. doi: 10.3389/fneur.2013.00055. eCollection 2013.
Epilepsy may reflect a focal abnormality of cerebral tissue, but the generation of seizures typically involves propagation of abnormal activity through cerebral networks. We examined epileptiform discharges (spikes) with dense array electroencephalography (dEEG) in five patients to search for the possible engagement of pathological networks. Source analysis was conducted with individual electrical head models for each patient, including sensor position measurement for registration with MRI with geodesic photogrammetry; tissue segmentation and skull conductivity modeling with an atlas skull warped to each patient's MRI; cortical surface extraction and tessellation into 1 cm(2) equivalent dipole patches; inverse source estimation with either minimum norm or cortical surface Laplacian constraints; and spectral coherence computed among equivalent dipoles aggregated within Brodmann areas with 1 Hz resolution from 1 to 70 Hz. These analyses revealed characteristic source coherence patterns in each patient during the pre-spike, spike, and post-spike intervals. For one patient with both spikes and seizure onset localized to a single temporal lobe, we observed a cluster of apparently abnormal coherences over the involved temporal lobe. For the other patients, there were apparently characteristic coherence patterns associated with the discharges, and in some cases these appeared to reflect abnormal temporal lobe synchronization, but the coherence patterns for these patients were not easily related to an unequivocal epileptogenic zone. In contrast, simple localization of the site of onset of the spike discharge, and/or the site of onset of the seizure, with non-invasive 256 dEEG was useful in predicting the characteristic site of seizure onset for those cases that were verified by intracranial EEG and/or by surgical outcome.
癫痫可能反映了脑组织的局灶性异常，但发作的产生通常涉及异常活动通过脑网络的传播。我们使用密集型脑电阵列（dEEG）检查了五名患者的癫痫样放电（棘波），以寻找可能涉及的病理网络。源分析是针对每位患者的个体电头模型进行的，包括传感器位置测量，以便与基于测地线摄影术的 MRI 进行配准；组织分割和颅骨电导率建模，使用针对每位患者 MRI 扭曲的图谱颅骨；皮质表面提取和细分到 1cm²等效偶极子贴片；使用最小范数或皮质表面拉普拉斯约束进行逆源估计；以及在 Brodmann 区域内以 1Hz 分辨率从 1 到 70Hz 聚集的等效偶极子之间计算频谱相干性。这些分析在每个患者的棘波前、棘波和棘波后期间揭示了特征性的源相干模式。对于一个既有棘波又有癫痫发作起始定位于单个颞叶的患者，我们观察到涉及颞叶的明显异常相干簇。对于其他患者，存在与放电明显相关的特征性相干模式，在某些情况下，这些模式似乎反映了颞叶异常同步，但这些患者的相干模式不容易与明确的致痫区相关。相比之下，使用 256 个 dEEG 对棘波放电和/或癫痫发作起始部位进行简单定位，对于那些通过颅内 EEG 和/或手术结果得到验证的病例，有助于预测癫痫发作起始的特征部位。
