Remote changes in cortical excitability after stroke
Remote changes in cortical excitability after stroke
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DOI：
10.1093/brain/awg044
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发表时间：
2003-02-01
期刊：
影响因子：
14.5
通讯作者：
Hömberg, V
中科院分区：
文献类型：
--
作者：
Bütefisch, CM;Netz, J;Hömberg, V
在动物和人类中，已经报道了远离缺血性脑损伤的脑代谢和脑区兴奋性的变化，并被认为是与功能恢复相关的机制。本研究的目的是确定是否在非受影响的大脑半球的运动皮层的抑制和兴奋活动的变化存在于中风患者，以及这些变化是否与患者的功能恢复的程度。采用经颅磁刺激（TMS）对13例脑卒中后手功能恢复良好的患者健侧第一骨间背侧肌（FDI）进行研究，并与13例年龄匹配的健康志愿者左半球刺激进行比较。在第一个实验中，成对脉冲TMS与条件刺激（CS）设置在80%的受试者的运动阈值（MT）和刺激间期（ISI）的2，3，10和15毫秒。在第二个实验中，不同强度的CS被用来研究其抑制效果在ISI，保持恒定在2毫秒的后续阈上测试刺激。在第三个实验中，运动诱发电位（MEP）幅度的上升，随着刺激强度的增加进行了测量。在另外两个对照实验中，研究了正常志愿者的左半球与右半球刺激以及中风后患者的手功能恢复良好与不良对抑制和兴奋活动的兴奋性的影响。MT，平均测试MEP和募集曲线在患者和健康志愿者中相似。在这些患者恢复良好，成对脉冲兴奋性增加，在ISI的2和3毫秒，类似于健康志愿者在ISI的10和15毫秒。当测试不同的CS强度在ISI的2毫秒，抑制活性是相似的，在小CS强度的患者和健康受试者，但在较高的CS强度的患者迅速消退。相反，在恢复不佳的患者中，在较高CS强度下未观察到皮质兴奋性的增加。患者和健康志愿者的MT、平均测试MEP和募集曲线的相似性表明患者的整体皮质运动神经元兴奋性没有改变。恢复良好的患者和健康受试者在低CS强度下的抑制作用相似，恢复期患者在较高CS强度下条件MEP振幅的急剧增加表明，在患者的对侧损伤运动皮层中，在2和3 ms的ISI下测试的神经元回路中，兴奋性和抑制性活动的平衡朝着兴奋性活动增加的方向移动。与实验性脑损伤后的重组过程相关的机制有相似之处，可能与中风后的功能恢复有关。在恢复不佳的患者中，皮质兴奋性没有变化，这支持了我们的研究结果与恢复的相关性。
Changes in the cerebral metabolism and the excitability of brain areas remote from an ischaemic brain lesion have been reported in animals and humans and implicated as a mechanism relevant to functional recovery. The aim of the present study was to determine whether changes in the inhibitory and excitatory activity in motor cortex of the non-affected hemisphere are present in stroke patients, and whether these changes are related to the extent of the patients' recovery of function. Transcranial magnetic stimulation (TMS) was used to study the first dorsal interosseus muscle (FDI) of the non-affected hand in 13 patients with good recovery of hand function after stroke, and was compared with left hemispheric stimulation in 13 healthy age-matched volunteers. In the first experiment, paired-pulse TMS with the conditioning stimulus (CS) set at 80% of the subject's motor threshold (MT) and interstimulus intervals (ISIs) of 2, 3, 10 and 15 ms was used. In the second experiment, different intensities of CS were used to study its inhibitory effect on a succeeding suprathreshold test stimulus at an ISI that was kept constant at 2 ms. In a third experiment, the rise in motor evoked potential (MEP) amplitudes with increasing stimulus intensities was measured. In two additional control experiments, the effect of left versus right hemispheric stimulation in normal volunteers and good versus poor recovery of hand function in patients after stroke on the excitability of inhibitory and excitatory activity was studied. MT, mean test MEP and recruitment curves were similar in patients and healthy volunteers. In those patients with good recovery, paired-pulse excitability was increased at ISIs of 2 and 3 ms, similar to healthy volunteers at ISIs of 10 and 15 ms. When tested with different CS intensities at an ISI of 2 ms, inhibitory activity was similar in patients and healthy subjects at small CS intensities, but faded rapidly at higher CS intensities in patients. In contrast, in patients with poor recovery, this increase in cortical excitability at higher CS intensities was not seen. The similarity of MT, mean test MEP and recruitment curves in patients and healthy volunteers indicates that the overall cortico-motoneuronal excitability has not changed in patients. The similarity of the inhibitory effect at low CS intensities in the patients with good recovery and healthy subjects, and the steeper increase of conditioned MEP amplitude at higher CS intensities in the recovering patients suggest that in the patients' contralesional motor cortex the balance of excitatory and inhibitory activity was shifted towards an increase of excitatory activity in the neuronal circuits tested at ISIs of 2 and 3 ms. This shares similarities to mechanisms implicated as relevant for reorganizational processes after experimental brain injury and may be relevant for functional recovery after stroke. The absence of changes in cortical excitability in patients with poor recovery supports the relevance of our findings for recovery.