Department of Neurology, Université libre de Bruxelles (ULB), Hôpital Universitaire de Bruxelles (HUB), Hôpital Erasme, Bruxelles, Belgium.
Laboratoire de Neuroanatomie et Neuroimagerie translationnelles (LN2T), Université libre de Bruxelles (ULB), ULB Neuroscience Institute (UNI), Bruxelles, Belgium.
Ann Clin Transl Neurol. 2024 Oct;11(10):2645-2656. doi: 10.1002/acn3.52179. Epub 2024 Oct 6.
Cortico-cortical evoked potentials (CCEPs) were described as reproducible during trains of single-pulse electrical stimulations (SPES). Still, few studies described a variability of CCEPs that was higher within the epileptogenic zone (EZ). This study aimed at characterizing the relationship of CCEP variability with the occurrence of interictal/ictal epileptiform discharges at the temporal vicinity of the stimulation, but not during the stimulation, by effective connectivity modifications.
We retrospectively included 20 patients who underwent SPES during their stereo-electroencephalography (SEEG). We analyzed the variability of CCEPs by using the post-stimulation time course of intertrial standard deviation (amplitude) and the timing of peak amplitude signal of CCEP epochs (latency). Values were corrected for the Euclidian distance between stimulating/recording electrodes. Receiver operating characteristics curves were used to assess the relationship with the EZ. The link between CCEP variability and interictal discharges occurrence, seizure frequency prior to the SEEG recording, and number of seizures during SEEG recording was assessed with Spearman's correlations.
A relationship was demonstrated between the EZ and both the distance-corrected latency variation (area under the curve (AUC): 0.73-0.74) and the distance-corrected amplitude variation (AUC: 0.71-0.72) and both were related with the occurrence of seizures.
Seizures before/during SEEG impact the dynamics of effective connectivity within the epileptogenic network by reducing the variability of CCEP latency/amplitude when the seizure frequency increases. It suggests a strengthening of the epileptogenic network with the occurrence of many seizures. These findings stress the importance of early epilepsy surgery at a time when the network organization has not yet been complete.
皮质-皮质诱发电位（CCEPs）在单脉冲电刺激（SPES）的刺激过程中被描述为可重复的。然而，很少有研究描述了 CCEPs 在致痫区（EZ）内的变异性更高。本研究旨在通过有效连接性的改变，描述 CCEP 变异性与刺激颞区附近的发作间期/发作期癫痫样放电的发生之间的关系，但不是在刺激过程中。
我们回顾性纳入了 20 名在立体脑电图（SEEG）期间接受 SPES 的患者。我们通过使用刺激后试验间标准偏差（振幅）的时程和 CCEP 时段峰值振幅信号的时间（潜伏期）来分析 CCEPs 的变异性。值通过刺激/记录电极之间的欧几里得距离进行校正。使用受试者工作特征曲线来评估与 EZ 的关系。使用 Spearman 相关分析评估 CCEP 变异性与发作间期放电的发生、SEEG 记录前的发作频率以及 SEEG 记录期间的发作次数之间的关系。
证明 EZ 与距离校正后的潜伏期变化（曲线下面积（AUC）：0.73-0.74）和距离校正后的振幅变化（AUC：0.71-0.72）之间存在关系，并且两者都与发作的发生有关。
SEEG 前/期间的发作通过减少发作频率增加时 CCEP 潜伏期/振幅的变异性，影响致痫网络内有效连接的动力学。这表明随着发作次数的增加，致痫网络的强化。这些发现强调了在网络组织尚未完全形成时尽早进行癫痫手术的重要性。
