Sun Fangling, Wang Yingfan, Li Yihan, Li Yanzhang, Wang Siyi, Xu Fengyuan, Wang Xiaoshan
Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China.
Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China.
Seizure. 2023 Oct;111:109-121. doi: 10.1016/j.seizure.2023.08.005. Epub 2023 Aug 15.
Two types of spike-and-wave discharges (SWDs) exist in childhood absence epilepsy (CAE): clinical discharges are prolonged and manifest primarily as impaired consciousness, whereas subclinical discharges are brief with few objectively visible symptoms. This study aimed to compare neural functional network and default mode network (DMN) activity between clinical and subclinical discharges to better understand the underlying mechanism of CAE.
Using magnetoencephalography (MEG) data from 21 patients, we obtained 25 segments each of clinical discharges and subclinical discharges. Amplitude envelope correlation analysis was used to construct functional networks and graph theory was used to calculate network topological data. We then compared differences in functional connectivity within the DMN between clinical and subclinical discharges. All statistical comparisons were performed using paired-sample tests.
Compared to subclinical discharges, the functional network of clinical discharges exhibited higher synchronization - particularly in the parahippocampal gyrus - as early as 10 s before the seizure. Additionally, the functional network of clinical SWDs presented an anterior shift of key nodes in the alpha frequency band. Regarding clinical discharge progression, there were gradual increases in the parameter node strengths (S), clustering coefficients (C), and global efficiency (E) of the functional networks, while the path lengths (L) decreased. These changes were most prominent at the onset of discharges and followed by some recovery in the high-frequency bands, but no significant change in the low-frequency bands. Furthermore, connections within the DMN during the discharge period were significantly stronger for clinical discharge compared to subclinical discharges.
These findings suggest that a more regular network before abnormal discharges in clinical discharges contributes to SWD explosion and that the parahippocampal gyrus plays an important role in maintaining oscillations. An absence seizure is a gradual process and the emergence of SWDs may be accompanied by initiation of inhibitory mechanisms. Enhanced functional connectivity among DMN brain regions may indicate that patients have entered a state of introspection, and functional abnormalities in the parahippocampal gyrus may be associated with patients' transient memory loss.
儿童失神癫痫（CAE）存在两种类型的棘慢波放电（SWD）：临床放电持续时间长，主要表现为意识障碍，而亚临床放电短暂，客观可见症状较少。本研究旨在比较临床和亚临床放电之间的神经功能网络和默认模式网络（DMN）活动，以更好地理解CAE的潜在机制。
利用21例患者的脑磁图（MEG）数据，我们获得了临床放电和亚临床放电各25个片段。采用振幅包络相关分析构建功能网络，并运用图论计算网络拓扑数据。然后我们比较了临床和亚临床放电之间DMN内功能连接的差异。所有统计比较均采用配对样本检验。
与亚临床放电相比，临床放电的功能网络在癫痫发作前10秒就表现出更高的同步性——尤其是在海马旁回。此外，临床SWD的功能网络在α频段关键节点出现前移。关于临床放电进展，功能网络的参数节点强度（S）、聚类系数（C）和全局效率（E）逐渐增加，而路径长度（L）减小。这些变化在放电开始时最为显著，随后在高频带有所恢复，但低频带无显著变化。此外，与亚临床放电相比，临床放电期间DMN内的连接明显更强。
这些发现表明，临床放电中异常放电前更规则的网络有助于SWD爆发，海马旁回在维持振荡中起重要作用。失神发作是一个渐进过程，SWD的出现可能伴随着抑制机制的启动。DMN脑区之间增强的功能连接可能表明患者已进入内省状态，海马旁回的功能异常可能与患者的短暂记忆丧失有关。
