Table_3_Altered neuromagnetic activity in default mode network in childhood absence epilepsy.docx

PurposeThe 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.
MethodsUsing 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.
ResultsDefault 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 (pcorrected < 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 (pcorrected < 0.01), whereas the values of all DMN regions in the beta-gamma 2 band were significantly decreased (pcorrected < 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 (pcorrected < 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, pcorrected < 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, pcorrected < 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, pcorrected < 0.01) such that it was no longer the central hub.
ConclusionThese 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.

研究背景：儿童失神癫痫（Childhood Absence Epilepsy, CAE）发作间期默认模式网络（Default Mode Network, DMN）内的静息态振荡功能连接的电生理特征仍未明确。本研究借助脑磁图（Magnetoencephalography, MEG）记录技术，探讨CAE患者DMN内连接的异常变化。
方法：本研究采用横断面设计，对33例新确诊CAE患儿及26例年龄、性别匹配的健康对照者的MEG数据进行分析。采用最小范数估计结合Welch法与校正后振幅包络相关性，估算DMN的谱功率与功能连接。
结果：发作期DMN在δ频段表现出更强的激活，但其余频段的相对谱功率均显著低于发作间期（校正后P<0.05；DMN脑区中，θ频段除外双侧内侧前额叶皮层、左侧内侧颞叶、左侧后扣带回皮层，α频段除外双侧楔前叶）。值得注意的是，与发作间期数据相比，α频段的显著谱功率峰值消失。与健康对照相比，CAE患者发作间期DMN脑区（双侧楔前叶除外）在δ频段的相对谱功率显著升高（校正后P<0.01），而所有DMN脑区在β-γ2频段的相对谱功率均显著降低（校正后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脑区发作期节点强度均显著高于发作间期（校正后P<0.01）；其中右侧下顶叶的节点强度在β频段升高最为显著（发作期：3.8712 vs 发作间期：0.7503，校正后P<0.01）。与健康对照相比，CAE患者发作间期DMN的节点强度在所有频段均升高，尤以β频段的右侧内侧前额叶皮层最为明显（对照组：0.1510 vs 发作间期：3.527，校正后P<0.01）。组间相对节点强度比较显示，CAE患儿右侧楔前叶的节点强度显著降低（β频段：对照组0.1009 vs 发作间期0.0475；γ1频段：对照组0.1149 vs 发作间期0.0587，校正后P<0.01），使其不再作为中枢枢纽存在。
结论：本研究结果表明，CAE患者的DMN存在异常，即使在无发作间期癫痫样放电的发作间期亦是如此。CAE患者的功能连接异常可能反映了DMN的解剖-功能整合结构异常，这与失神发作期间的认知损害及意识障碍相关。未来仍需开展研究，明确这种异常的功能连接能否作为CAE患者治疗反应、认知功能障碍及预后评估的生物标志物。