Brancaccio Arianna, Tabarelli Davide, Baur David, Roesch Johanna, Mahmoud Wala, Ziemann Ulf, Belardinelli Paolo
Center for Mind/Brain Sciences-CIMeC, University of Trento I-38123 Trento, Italy.
Department of Neurology & Stroke, University of Tübingen, Germany; Hertie-Institute for Clinical Brain Research, University of Tübingen, Germany.
Clin Neurophysiol. 2025 Jul;175:2110747. doi: 10.1016/j.clinph.2025.2110747. Epub 2025 May 19.
In healthy subjects, the trough vs. no-trough phases of the sensorimotor µ-rhythm correspond to high- vs. low-excitability states of the motor cortex (M1). We tested this excitability differentiation in the ipsilesional (iM1) and contralesional M1 (cM1) of chronic stroke patients.
19 chronic stroke patients received single-pulse transcranial magnetic stimulation (TMS), separately over the iM1 and cM1, during EEG recordings. High and low M1 excitability states were defined by binning a post-hoc estimate of the µ-phase at TMS delivery. TMS-evoked EEG potentials (TEPs) and time-frequency responses were characterized for excitability states and hemispheres. The motor function of the affected arm was tested by the Fugl-Meyer Assessment Upper Extremity (FMA-UE.
In cM1, TMS at the high- vs. low-excitability state resulted in larger TEP amplitudes and increased post-pulse power in the beta band. In iM1, these modulations were not significant except for post-pulse beta power. This retained excitability differentiation significantly correlated with FMA-UE.
The degree of excitability differentiation in iM1 depending on phase of the sensorimotor µ-rhythm correlates with individual affected upper extremity motor function.
The degree of excitability differentiation in iM1 might serve as a new independent marker of motor recovery.
在健康受试者中，感觉运动μ节律的波谷期与非波谷期分别对应运动皮层（M1）的高兴奋性状态和低兴奋性状态。我们在慢性卒中患者的患侧M1（iM1）和健侧M1（cM1）中测试了这种兴奋性差异。
19例慢性卒中患者在脑电图记录期间，分别在iM1和cM1上接受单脉冲经颅磁刺激（TMS）。通过对TMS发放时μ相位的事后估计进行分组，定义M1的高兴奋性状态和低兴奋性状态。对TMS诱发的脑电电位（TEP）和时频反应的兴奋性状态及半球进行特征描述。采用Fugl-Meyer上肢评估量表（FMA-UE）测试患侧上肢的运动功能。
在cM1中，高兴奋性状态与低兴奋性状态下的TMS相比，TEP波幅更大，β频段的脉冲后功率增加。在iM1中，除了脉冲后β功率外，这些调制不显著。这种保留的兴奋性差异与FMA-UE显著相关。
iM1中兴奋性差异的程度取决于感觉运动μ节律的相位，与个体患侧上肢运动功能相关。
iM1中兴奋性差异的程度可能作为运动恢复的一个新的独立标志物。
