The location of interictal spikes is used to aid surgical planning in patients with medically refractory epilepsy; however, their spatial and temporal dynamics are poorly understood. In this study, we analysed the spatial distribution of interictal spikes over time in 20 adult and paediatric patients (12 females, mean age = 34.5 years, range = 5-58) who underwent intracranial EEG evaluation for epilepsy surgery. Interictal spikes were detected in the 24 h surrounding each seizure and spikes were clustered based on spatial location. The temporal dynamics of spike spatial distribution were calculated for each patient and the effects of sleep and seizures on these dynamics were evaluated. Finally, spike location was assessed in relation to seizure onset location. We found that spike spatial distribution fluctuated significantly over time in 14/20 patients (with a significant aggregate effect across patients, Fisher's method: P < 0.001). A median of 12 sequential hours were required to capture 80% of the variability in spike spatial distribution. Sleep and postictal state affected the spike spatial distribution in 8/20 and 4/20 patients, respectively, with a significant aggregate effect (Fisher's method: P < 0.001 for each). There was no evidence of pre-ictal change in the spike spatial distribution for any patient or in aggregate (Fisher's method: P = 0.99). The electrode with the highest spike frequency and the electrode with the largest area of downstream spike propagation both localized the seizure onset zone better than predicted by chance (Wilcoxon signed-rank test: P = 0.005 and P = 0.002, respectively). In conclusion, spikes localize seizure onset. However, temporal fluctuations in spike spatial distribution, particularly in relation to sleep and post-ictal state, can confound localization. An adequate duration of intracranial recording-ideally at least 12 sequential hours-capturing both sleep and wakefulness should be obtained to sufficiently sample the interictal network.

中文翻译：

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耳尖突的空间分布随时间波动，并局部发作。

尖峰间的位置用于辅助患有难治性癫痫患者的手术计划；但是，人们对它们的时空动态知之甚少。在这项研究中，我们分析了接受颅内脑电图评估癫痫手术的20名成年和小儿患者（12名女性，平均年龄= 34.5岁，范围= 5-58）间的尖峰间隔随时间的空间分布。在每次发作的24小时内检测到发作间期峰值，并根据空间位置对峰值进行聚类。计算每个患者的峰值空间分布的时间动态，并评估睡眠和癫痫发作对这些动态的影响。最后，根据癫痫发作的发作位置评估了刺的位置。我们发现，峰值空间分布随时间的推移在14/20患者中有明显波动（对患者产生显着的总体影响，Fisher方法：P <0.001）。捕获峰值空间分布中80％的变异性需要12个连续小时的中位数。睡眠和姿势状态分别影响8/20和4/20患者的峰值空间分布，具有明显的总体效应（费希尔方法：每人P <0.001）。没有证据表明任何患者或总体患者峰值空间分布出现前期变化（Fisher方法：P = 0.99）。尖峰频率最高的电极和下游尖峰传播面积最大的电极对癫痫发作区的定位都比偶然预测的要好（Wilcoxon有符号秩检验：P = 0。005和P = 0.002）。总之，尖峰使癫痫发作发作局部化。但是，峰值空间分布的时间波动（尤其是与睡眠和发作后状态有关）会混淆定位。应当有足够的颅内记录持续时间，最好是至少连续12个小时，以捕获睡眠和清醒，以充分采样间质网络。