Gray Whitney A, Palmer Jacqueline A, Wolf Steven L, Borich Michael R
1 Division of Physical Therapy, Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA, USA.
2 Atlanta VA Center for Visual and Neurocognitive Rehabilitation, Decatur, GA, USA.
Neurorehabil Neural Repair. 2017 Jul;31(7):666-676. doi: 10.1177/1545968317712470. Epub 2017 Jun 12.
Abnormal brain excitability influences recovery after stroke at which time a prolonged transcranial magnetic stimulation (TMS)-induced electromyographic silent period is thought to reflect abnormal inhibitory interneuron excitability. Cortical excitability can be probed directly during the silent period using concurrent electroencephalography (EEG) of TMS-evoked responses.
The primary study objectives were to characterize TMS-evoked cortical potentials (TEPs) using EEG and to investigate associations with persistent hand and arm motor dysfunction in individuals with chronic stroke.
Thirteen participants with chronic stroke-related mild-moderate arm motor impairment and 12 matched controls completed a single TMS-EEG cortical excitability assessment. TEPs recorded from the vertex during cortical silent period (CSP) assessment and while at rest were used to evaluate differences in cortical excitability between stroke and control participants. Associations between TEPs and CSP duration with measures of upper extremity motor behavior were investigated.
Significantly increased TEP component peak amplitudes and delayed latencies were observed for stroke participants compared with controls during CSP assessment and while at rest. Delayed early TEP component (P30) peak latencies during CSP assessment were associated with less manual dexterity. CSP duration was prolonged in stroke participants, and correlated with P30 peak latency and paretic arm dysfunction.
Abnormal cortical excitability directly measured by early TMS-evoked EEG responses during CSP assessment suggests abnormal cortical inhibition is associated with hand dysfunction in chronic stroke. Further investigation of abnormal cortical inhibition in specific brain networks is necessary to characterize the salient neurophysiologic mechanisms contributing to persistent motor dysfunction after stroke.
大脑兴奋性异常会影响中风后的恢复，此时经颅磁刺激（TMS）诱发的肌电图静息期延长被认为反映了抑制性中间神经元兴奋性异常。在静息期可使用TMS诱发反应的同步脑电图（EEG）直接探测皮层兴奋性。
主要研究目的是利用EEG对TMS诱发的皮层电位（TEP）进行特征描述，并调查慢性中风患者持续性手部和手臂运动功能障碍之间的关联。
13名患有慢性中风相关轻至中度手臂运动障碍的参与者和12名匹配的对照组完成了单次TMS-EEG皮层兴奋性评估。在皮层静息期（CSP）评估期间以及静息时从头顶记录的TEP用于评估中风患者和对照参与者之间皮层兴奋性的差异。研究了TEP和CSP持续时间与上肢运动行为测量值之间的关联。
与对照组相比，中风参与者在CSP评估期间以及静息时观察到TEP成分峰值幅度显著增加且潜伏期延迟。CSP评估期间早期TEP成分（P30）峰值潜伏期延迟与手部灵活性降低有关。中风参与者的CSP持续时间延长，且与P30峰值潜伏期和患侧手臂功能障碍相关。
在CSP评估期间通过早期TMS诱发的EEG反应直接测量的皮层兴奋性异常表明，皮层抑制异常与慢性中风患者的手部功能障碍有关。有必要进一步研究特定脑网络中的皮层抑制异常，以确定导致中风后持续性运动功能障碍的显著神经生理机制。
