The ratio between slower and faster frequencies of brain activity may change after stroke. However, few studies have used quantitative electroencephalography (qEEG) index of ratios between slower and faster frequencies such as the delta/alpha ratio (DAR) and the power ratio index (PRI; ) for investigating the difference between the affected and unaffected hemisphere poststroke. Here, we proposed a new perspective for analyzing DAR and PRI within each hemisphere and investigated the motor impairment-related interhemispheric frequency oscillations. Forty-seven poststroke subjects and twelve healthy controls were included in the study. Severity of upper limb motor impairment was classified according to the Fugl–Meyer assessment in mild/moderate () and severe (). The qEEG indexes (PRI and DAR) were computed for each hemisphere (intrahemispheric index) and for both hemispheres (cerebral index). Considering the cerebral index (DAR and PRI), our results showed a slowing in brain activity in poststroke patients when compared to healthy controls. Only the intrahemispheric PRI index was able to find significant interhemispheric differences of frequency oscillations. Despite being unable to detect interhemispheric differences, the DAR index seems to be more sensitive to detect motor impairment-related frequency oscillations. The intrahemispheric PRI index may provide insights into therapeutic approaches for interhemispheric asymmetry after stroke.

中文翻译：

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半球内脑电图：中风后个体脑电图定量评估的新视角

中风后大脑活动的较慢和较快频率之间的比率可能会发生变化。然而，很少有研究使用定量脑电图 (qEEG) 指数来衡量较慢和较快频率之间的比率，例如 delta/alpha 比率 (DAR) 和功率比率指数 (PRI;)用于调查受影响和未受影响的脑卒中后半球之间的差异。在这里，我们提出了一个新的视角来分析每个半球内的 DAR 和 PRI，并研究了与运动损伤相关的半球间频率振荡。该研究包括 47 名卒中后受试者和 12 名健康对照者。上肢运动障碍的严重程度根据 Fugl-Meyer 评估分为轻度/中度（)和严重的 (）。qEEG 指数（PRI 和 DAR）针对每个半球（半球内指数）和两个半球（大脑指数）计算。考虑到大脑指数（DAR 和 PRI），我们的结果显示，与健康对照组相比，中风后患者的大脑活动减慢。只有半球内 PRI 指数能够发现频率振荡的显着半球间差异。尽管无法检测到大脑半球间的差异，但 DAR 指数似乎对检测与运动损伤相关的频率振荡更敏感。大脑半球内 PRI 指数可以为脑卒中后大脑半球间不对称的治疗方法提供见解。