Epilepsy Center Frankfurt Rhine-Main, Center of Neurology and Neurosurgery, University Hospital Frankfurt, Frankfurt am Main, Germany.
LOEWE Center for Personalized Translational Epilepsy Research (CePTER), Goethe University Frankfurt, Frankfurt am Main, Germany.
Brain Behav. 2023 Nov;13(11):e3257. doi: 10.1002/brb3.3257. Epub 2023 Sep 26.
Delta power is a clinically established biomarker for abnormal brain processes. However, in patients with unilateral focal epilepsy (FE) it is still not well understood, how it relates to the epileptogenic zone and to neurocognitive functioning. The aim of the present study was thus to assess how delta power relates to the affected hemisphere, whether lateralization strength differs between the patients, and how changes in delta power correlate with cognitive functioning.
We retrospectively studied patients with left (LFE) and right FE (RFE) who had undergone a resting-state magnetoencephalography measurement. We computed global and hemispheric delta power and lateralization indices and examined whether delta power correlates with semantic and letter verbal fluency (former being a marker for language and verbal memory, latter for executive functions) in 26 FE patients (15 LFE, 11 RFE) and 10 healthy controls.
Delta power was increased in FE patients compared to healthy controls. However, the increase across hemispheres was related to the site of the epileptic focus: On group level, LFE patients showed higher delta power in both hemispheres, whereas RFE patients primarily exhibited higher delta power in the ipsilateral right hemisphere. Both groups showed co-fluctuations of delta power between the hemispheres. Besides, delta power correlated negatively only with letter verbal fluency.
The findings confirm and provide further evidence that delta power is a marker of pathological activity and abnormal brain processes in FE. Delta power dynamics differ between patient groups, indicating that delta power could offer additional diagnostic value. The negative association of delta power and letter verbal fluency suggests that executive dysfunctions are related to low frequency abnormalities.
Delta 功率是一种临床确立的用于评估异常大脑过程的生物标志物。然而，在单侧局灶性癫痫（FE）患者中，其与致痫区以及神经认知功能的关系仍不明确。因此，本研究旨在评估 Delta 功率与受影响的脑半球之间的关系，患者之间的侧化强度是否存在差异，以及 Delta 功率的变化如何与认知功能相关。
我们回顾性地研究了接受静息态脑磁图测量的左（LFE）和右（RFE）侧 FE 患者。我们计算了全局和半球 Delta 功率和侧化指数，并在 26 名 FE 患者（15 名 LFE，11 名 RFE）和 10 名健康对照者中，检查了 Delta 功率是否与语义和字母流畅性相关（前者是语言和言语记忆的标志物，后者是执行功能的标志物）。
与健康对照组相比，FE 患者的 Delta 功率增加。然而，跨半球的增加与癫痫灶的位置有关：在组水平上，LFE 患者的两个半球的 Delta 功率均升高，而 RFE 患者主要表现为同侧右半球的 Delta 功率升高。两个组的 Delta 功率在半球之间都存在共同波动。此外，Delta 功率仅与字母流畅性呈负相关。
这些发现证实并进一步证明，Delta 功率是 FE 中病理性活动和异常大脑过程的标志物。Delta 功率动力学在患者组之间存在差异，这表明 Delta 功率可能提供额外的诊断价值。Delta 功率与字母流畅性之间的负相关表明，执行功能障碍与低频异常有关。
