Neurorehabilitation Department, IRCCS Istituti Clinici Scientifici Salvatore Maugeri di Milano, 20138 Milan, Italy.
Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Italy.
Clin Neurophysiol. 2022 May;137:92-101. doi: 10.1016/j.clinph.2022.02.022. Epub 2022 Mar 8.
Quantitative Electroencephalography (qEEG) can capture changes in brain activity following stroke. qEEG metrics traditionally focus on oscillatory activity, however recent findings highlight the importance of aperiodic (power-law) structure in characterizing pathological brain states. We assessed neurophysiological alterations and recovery after mono-hemispheric stroke by means of the Spectral Exponent (SE), a metric that reflects EEG slowing and quantifies the power-law decay of the EEG Power Spectral Density (PSD).
Eighteen patients (n = 18) with mild to moderate mono-hemispheric Middle Cerebral Artery (MCA) ischaemic stroke were retrospectively enrolled for this study. Patients underwent EEG recording in the sub-acute phase (T0) and after 2 months of physical rehabilitation (T1). Sixteen healthy controls (HC; n = 16) matched by age and sex were enrolled as a normative group. SE values and narrow-band PSD were estimated for each recording. We compared SE and band-power between patients and HC, and between the affected (AH) and unaffected hemisphere (UH) at T0 and T1 in patients.
At T0, stroke patients showed significantly more negative SE values than HC (p = 0.003), reflecting broad-band EEG slowing. Most important, in patients SE over the AH was consistently more negative compared to the UH and showed a renormalization at T1. This SE renormalization significantly correlated with National Institute of Health Stroke Scale (NIHSS) improvement (R = 0.63, p = 0.005).
SE is a reliable readout of the neurophysiological and clinical alterations occurring after an ischaemic cortical lesion.
SE promise to be a robust method to monitor and predict patients' functional outcome.
定量脑电图（qEEG）可捕捉中风后大脑活动的变化。qEEG 指标传统上侧重于振荡活动，然而最近的研究结果强调了非周期性（幂律）结构在表征病理性脑状态中的重要性。我们通过频谱指数（SE）评估单半球卒中后的神经生理改变和恢复情况，SE 是一种反映脑电图减慢并量化脑电图功率谱密度（PSD）的幂律衰减的指标。
本研究回顾性纳入 18 例轻度至中度大脑中动脉（MCA）单侧缺血性卒中患者（n=18）。患者在亚急性期（T0）和物理康复 2 个月后（T1）接受脑电图记录。纳入 16 名年龄和性别匹配的健康对照者（HC；n=16）作为正常组。为每个记录估计 SE 值和窄带 PSD。我们比较了患者和 HC 之间、T0 和 T1 时患者的受累侧（AH）和未受累侧（UH）之间的 SE 值和波段功率。
在 T0，卒中患者的 SE 值明显低于 HC（p=0.003），反映出宽带脑电图减慢。最重要的是，与 UH 相比，患者的 AH 上的 SE 始终更负，并在 T1 时出现正常化。这种 SE 正常化与国立卫生研究院卒中量表（NIHSS）改善显著相关（R=0.63，p=0.005）。
SE 是评估缺血性皮质病变后发生的神经生理和临床改变的可靠指标。
SE 有望成为监测和预测患者功能预后的有效方法。
