Wang Yingfan, Li Yihan, Sun Fangling, Xu Yue, Xu Fengyuan, Wang Siyi, Wang Xiaoshan
Department of Neurology, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing Medical University, Nanjing, China.
Front Neurosci. 2023 Mar 16;17:1133064. doi: 10.3389/fnins.2023.1133064. eCollection 2023.
The electrophysiological characterization of resting state oscillatory functional connectivity within the default mode network (DMN) during interictal periods in childhood absence epilepsy (CAE) remains unclear. Using magnetoencephalographic (MEG) recordings, this study investigated how the connectivity within the DMN was altered in CAE.
Using a cross-sectional design, we analyzed MEG data from 33 children newly diagnosed with CAE and 26 controls matched for age and sex. The spectral power and functional connectivity of the DMN were estimated using minimum norm estimation combined with the Welch technique and corrected amplitude envelope correlation.
Default mode network showed stronger activation in the delta band during the ictal period, however, the relative spectral power in other bands was significantly lower than that in the interictal period ( < 0.05 for DMN regions, except bilateral medial frontal cortex, left medial temporal lobe, left posterior cingulate cortex in the theta band, and the bilateral precuneus in the alpha band). It should be noted that the significant power peak in the alpha band was lost compared with the interictal data. Compared with controls, the interictal relative spectral power of DMN regions (except bilateral precuneus) in CAE patients was significantly increased in the delta band ( < 0.01), whereas the values of all DMN regions in the beta-gamma 2 band were significantly decreased ( < 0.01). In the higher frequency band (alpha-gamma1), especially in the beta and gamma1 band, the ictal node strength of DMN regions except the left precuneus was significantly higher than that in the interictal periods ( < 0.01), and the node strength of the right inferior parietal lobe increased most significantly in the beta band (Ictal: 3.8712 vs. Interictal: 0.7503, < 0.01). Compared with the controls, the interictal node strength of DMN increased in all frequency bands, especially the right medial frontal cortex in the beta band (Controls: 0.1510 vs. Interictal: 3.527, < 0.01). Comparing relative node strength between groups, the right precuneus in CAE children decreased significantly (β: Controls: 0.1009 vs. Interictal: 0.0475; γ 1: Controls:0.1149 vs. Interictal:0.0587, < 0.01) such that it was no longer the central hub.
These findings indicated DMN abnormalities in CAE patients, even in interictal periods without interictal epileptic discharges. Abnormal functional connectivity in CAE may reflect abnormal anatomo-functional architectural integration in DMN, as a result of cognitive mental impairment and unconsciousness during absence seizure. Future studies are needed to examine if the altered functional connectivity can be used as a biomarker for treatment responses, cognitive dysfunction, and prognosis in CAE patients.
儿童失神癫痫（CAE）发作间期默认模式网络（DMN）内静息态振荡功能连接的电生理特征仍不清楚。本研究利用脑磁图（MEG）记录，调查了CAE中DMN内的连接性是如何改变的。
采用横断面设计，我们分析了33例新诊断为CAE的儿童和26例年龄及性别匹配的对照组儿童的MEG数据。使用最小范数估计结合 Welch 技术和校正幅度包络相关性来估计DMN的频谱功率和功能连接。
默认模式网络在发作期δ频段显示出更强的激活，然而，其他频段的相对频谱功率显著低于发作间期（DMN区域，除双侧内侧额叶皮质、左侧内侧颞叶、θ频段的左侧后扣带回皮质以及α频段的双侧楔前叶外，P<0.05）。需要注意的是，与发作间期数据相比，α频段的显著功率峰值消失。与对照组相比，CAE患者DMN区域（除双侧楔前叶外）发作间期的相对频谱功率在δ频段显著增加（P<0.01），而β-γ2频段所有DMN区域的值均显著降低（P<0.01）。在较高频段（α-γ1），尤其是β和γ1频段，除左侧楔前叶外的DMN区域发作期节点强度显著高于发作间期（P<0.01），右侧顶下小叶在β频段的节点强度增加最为显著（发作期：3.8712 vs. 发作间期：0.7503，P<0.01）。与对照组相比，DMN的发作间期节点强度在所有频段均增加，尤其是β频段的右侧内侧额叶皮质（对照组：0.1510 vs. 发作间期：3.527，P<0.01）。比较组间相对节点强度，CAE儿童的右侧楔前叶显著降低（β：对照组：0.1009 vs. 发作间期：0.0475；γ1：对照组：0.1149 vs. 发作间期：0.0587，P<0.01），以至于它不再是中心枢纽。
这些发现表明CAE患者即使在无发作间期癫痫放电的发作间期，DMN也存在异常。CAE中异常的功能连接可能反映了DMN中解剖-功能结构整合异常是失神发作期间认知精神损害和意识丧失的结果。未来需要研究改变的功能连接是否可作为CAE患者治疗反应、认知功能障碍和预后的生物标志物。
