Objective: The hypersynchronous neuronal activity associated with epilepsy causes widespread functional network disruptions extending beyond the epileptogenic zone. This altered functional network topology is considered a mediator from which non-seizure symptoms arise, such as cognitive impairment. The aim of the present study was to demonstrate the presence of functional network alterations in focal epilepsy patients with good seizure control and high quality of life. Methods: We compared twenty-two focal epilepsy patients and sixteen healthy controls on graph metrics derived from functional connectivity (phase-locking value) of source reconstructed resting-state EEG. Graph metrics were calculated over a predefined range of network densities in five frequency bands. Results: In terms of global network topology alterations, we observed a significantly increased small world index in epilepsy patients relative to the healthy controls. On the local level, two left-hemisphere regions displayed a shift towards greater alpha band "hubness". Conclusions: Subtle widespread functional network alterations are evident in focal epilepsy, even in a cohort characterised by successful anti-seizure medication therapy and high quality of life. These findings suggest a possible clinical relevance of functional network analysis in epilepsy. Significance: Focal epilepsy is accompanied by global and local functional network aberrancies which might be implied in the sustenance of non-seizure symptoms.

中文翻译：

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源级脑电图和图论揭示局灶性癫痫中广泛的功能网络变化

目的：与癫痫相关的超同步神经元活动引起广泛的功能网络破坏，延伸至癫痫发生区之外。这种改变的功能网络拓扑被认为是介导非癫痫症状（例如认知障碍）的媒介。本研究的目的是证明癫痫发作控制良好且生活质量高的局灶性癫痫患者存在功能网络改变。方法：我们比较了源于静止状态脑电图的功能连通性（锁相值）的图形指标对22位局灶性癫痫患者和16位健康对照进行了比较。图形指标是在五个频段的网络密度的预定范围内计算的。结果：就全局网络拓扑更改而言，我们观察到，相对于健康对照组，癫痫患者的小世界指数显着增加。在局部水平上，两个左半球区域显示出向更大的Alpha波段“柔韧性”的转变。结论：即使在以成功的抗癫痫药物治疗和高生活质量为特征的人群中，局灶性癫痫中也存在明显的细微功能网络改变。这些发现提示功能网络分析在癫痫中可能具有临床意义。意义：局灶性癫痫伴有全球和局部功能网络异常，这可能暗示着非癫痫症状的维持。两个左半球区域显示了向更大的alpha波段“柔韧性”的转变。结论：即使在以成功的抗癫痫药物治疗和高生活质量为特征的人群中，局灶性癫痫中也存在明显的细微功能网络改变。这些发现提示功能网络分析在癫痫中可能具有临床意义。意义：局灶性癫痫伴有全球和局部功能网络异常，这可能暗示着非癫痫症状的维持。两个左半球区域显示了向更大的alpha波段“柔韧性”的转变。结论：即使在以成功的抗癫痫药物治疗和高生活质量为特征的人群中，局灶性癫痫中也存在明显的细微功能网络改变。这些发现提示功能网络分析在癫痫中可能具有临床意义。意义：局灶性癫痫伴有全球和局部功能网络异常，这可能暗示着非癫痫症状的维持。