Background. The time course of cortical activation and its relation with clinical measures may elucidate mechanisms underlying spontaneous neurobiological recovery after stroke. Objective. We aimed to investigate (1) the time course of cortical activation as revealed by EEG-based spectral characteristics during awake rest and (2) the development of these spectral characteristics in relation to global neurological and upper-limb motor recovery in the first 6 months poststroke. Methods. Resting-state EEG was measured serially in 41 patients after a first-ever ischemic stroke, within 3 and at 5, 12, and 26 weeks poststroke. We computed the brain symmetry index (BSI) and directional BSI (BSIdir) over different frequency bands (1-25 Hz, delta, theta) and delta/alpha ratio (DAR). The National Institutes of Health Stroke Scale (NIHSS) and Fugl-Meyer motor assessment of the upper extremity (FM-UE) were determined as clinical reflections of spontaneous neurobiological recovery. Longitudinal changes in spectral characteristics and within- and between-subject associations with NIHSS and FM-UE were analyzed with linear mixed models. Results. Spectral characteristics showed a gradual normalization over time, within and beyond 12 weeks poststroke. Significant within- and between-subject associations with NIHSS were found for DAR of the affected hemisphere (DARAH) and BSIdirdelta. BSIdirdelta also demonstrated significant within- and between-subject associations with FM-UE. Conclusions. Changes in spectral characteristics are not restricted to the time window of recovery of clinical neurological impairments. The present study suggests that decreasing DARAH and BSIdirdelta reflect improvement of global neurological impairments, whereas BSIdirdelta was also specifically associated with upper-limb motor recovery early poststroke.

中文翻译：

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静息状态的脑电图与卒中后早期临床神经损伤的恢复有纵向关联吗？一项前瞻性队列研究

背景。皮质激活的时间过程及其与临床测量的关系可能阐明中风后自发神经生物学恢复的机制。客观的。我们旨在研究 (1) 清醒休息期间基于 EEG 的光谱特征所揭示的皮层激活的时间过程，以及 (2) 这些光谱特征的发展与前 6 个月的整体神经和上肢运动恢复有关中风后。方法。在首次缺血性卒中后，在卒中后 3 周和 5、12 和 26 周内，连续测量了 41 名患者的静息态 EEG。我们计算了不同频段（1-25 Hz、delta、theta）和 delta/alpha 比率 (DAR) 上的大脑对称指数 (BSI) 和定向 BSI (BSIdir)。美国国立卫生研究院卒中量表 (NIHSS) 和 Fugl-Meyer 上肢运动评估 (FM-UE) 被确定为自发神经生物学恢复的临床反映。使用线性混合模型分析光谱特征的纵向变化以及与 NIHSS 和 FM-UE 的受试者内和受试者间关联。结果。光谱特征显示在中风后 12 周内和之后随时间逐渐正常化。在受影响的半球 (DARAH) 和 BSIdirdelta 的 DAR 中发现了与 NIHSS 的显着的受试者内和受试者间关联。BSIdirdelta 还证明了与 FM-UE 的受试者内和受试者间的显着关联。结论。光谱特性的变化不限于临床神经损伤恢复的时间窗口。