Abstract：
Interictal epileptiform discharges (IEDs) often co-occur across spatially-separated cortical regions, forming IED networks. However, the factors prompting IED propagation remain unelucidated. We hypothesized that slow oscillations (SOs) might facilitate IED propagation. Here, the amplitude and phase synchronization of SOs preceding propagating and non-propagating IEDs were compared in 22 patients with focal epilepsy undergoing intracranial electroencephalography (EEG) evaluation. Intracranial channels were categorized into the irritative zone (IZ) and normal zone (NOZ) regarding the presence of IEDs. During wakefulness, we found that pre-IED SOs within the IZ exhibited higher amplitudes for propagating IEDs than non-propagating IEDs (delta band: p = 0.001, theta band: p < 0.001). This increase in SOs was also concurrently observed in the NOZ (delta band: p = 0.04). Similarly, the inter-channel phase synchronization of SOs prior to propagating IEDs was higher than those preceding non-propagating IEDs in the IZ (delta band: p = 0.04). Through sliding window analysis, we observed that SOs preceding propagating IEDs progressively increased in amplitude and phase synchronization, while those preceding non-propagating IEDs remained relatively stable. Significant differences in amplitude occurred approximately 1150 ms before IEDs. During non-rapid eye movement (NREM) sleep, SOs on scalp recordings also showed higher amplitudes before intracranial propagating IEDs than before non-propagating IEDs (delta band: p = 0.006). Furthermore, the analysis of IED density around sleep SOs revealed that only high-amplitude sleep SOs demonstrated correlation with IED propagation. Overall, our study highlights that transient but widely distributed SOs are associated with IED propagation as well as generation in focal epilepsy during sleep and wakefulness, providing new insight into the EEG substrate supporting IED networks.
摘要：
发作间癫痫样放电（IED）通常在空间分离的皮质区域同时发生，形成简易爆炸装置网络。然而,促使IED传播的因素仍未阐明。我们假设缓慢振荡（SO）可能会促进IED的传播。这里,在接受颅内脑电图（EEG）评估的22例局灶性癫痫患者中，比较了传播和非传播IED之前的SO的振幅和相位同步。根据IED的存在，颅内通道分为刺激区（IZ）和正常区（NOZ）。在清醒的时候,我们发现，IZ内的IED前SOs对传播的IED比非传播的IED表现出更高的振幅（δ带：p=0.001，θ带：p<0.001）。在NOZ中也同时观察到SO的这种增加(δ带:p=0.04)。同样，传播IED之前的S0的信道间相位同步高于IZ中先前的非传播IED(delta频带:p=0.04)。通过滑动窗口分析,我们观察到传播IED之前的SO在幅度和相位同步方面逐渐增加，而那些之前的非传播IED保持相对稳定。在IED之前大约1150ms发生幅度的显著差异。在非快速眼动（NREM）睡眠期间，头皮记录上的SOs在颅内传播IED之前也显示出比非传播IED之前更高的幅度（δ带：p=0.006）。此外，对睡眠SO周围IED密度的分析表明，只有高振幅睡眠SO显示出与IED传播相关。总的来说,我们的研究强调，短暂但分布广泛的SO与IED传播以及睡眠和觉醒期间局灶性癫痫的产生有关，为支持IED网络的EEG基板提供新的见解。
