Small S L, Hlustik P, Noll D C, Genovese C, Solodkin A
Department of Neurology and Brain Research Imaging Center, The University of Chicago, IL 60637, USA.
Brain. 2002 Jul;125(Pt 7):1544-57. doi: 10.1093/brain/awf148.
An experimental lesion in the primary motor or sensory cortices in monkeys leads to functional reorganization in areas surrounding the lesion or in contralateral homologous regions. In humans, task-dependent brain activation after motor stroke seems to be multifocal and bilateral. Although many active structures are seen after stroke, their roles are unclear. For instance, the uninjured primary motor cortex may play a significant role in recovery or may be associated with mirror movements. Other motor areas, particularly those outside the affected middle cerebral artery distribution, have also been thought to play such a role, including the medial pre-motor areas and both cerebellar hemispheres. The lateral pre-motor areas might also contribute but the demarcation of primary motor and pre-motor cortices is not trivial. It is not known from existing studies how brain activation relates to behavioural change over the time course of recovery. We used functional MRI (fMRI) to study 12 patients longitudinally over the first 6 months of stroke recovery. All subjects had acute stroke causing unilateral arm weakness and had some ability to move the impaired hand within 1 month. Each patient had both motor testing and fMRI during finger and wrist movements at four points during the observed period. Six of these patients showed good motor recovery, whereas the other six did not. The imaging results support a role for the cerebellum in mediating functional recovery from stroke. The data suggest that patients with good recovery have clear changes in the activation of the cerebellar hemisphere opposite the injured corticospinal tract. Patients with poor recovery do not show such changes in cerebellar activation. No other brain region had a significant correlation with recovery. Interestingly, activation in the cerebellum ipsilateral to the injury increases transiently after stroke, independently of the success of recovery. The present work suggests a possible link between cerebellar activation and behavioural recovery from hand weakness from stroke. The underlying mechanism is not known, but it could relate to haemodynamic changes such as diaschisis or to the postulated role of the cerebellum in motor skill learning.
猴子初级运动皮层或感觉皮层的实验性损伤会导致损伤周围区域或对侧同源区域发生功能重组。在人类中，运动性中风后任务依赖的脑激活似乎是多灶性和双侧性的。尽管中风后可见许多活跃结构，但其作用尚不清楚。例如，未受损的初级运动皮层可能在恢复中起重要作用，或者可能与镜像运动有关。其他运动区域，特别是那些在受影响的大脑中动脉分布区域之外的区域，也被认为起到这样的作用，包括内侧运动前区和两个小脑半球。外侧运动前区可能也有作用，但初级运动皮层和运动前皮层的划分并非易事。现有研究尚不清楚在恢复的时间过程中脑激活与行为变化之间的关系。我们使用功能磁共振成像（fMRI）对12名患者在中风恢复的前6个月进行了纵向研究。所有受试者均患有急性中风，导致单侧手臂无力，且在1个月内患手有一定的活动能力。在观察期内的四个时间点，每位患者在手指和手腕运动时均进行了运动测试和fMRI检查。其中6名患者运动恢复良好，而另外6名患者则没有。成像结果支持小脑在介导中风功能恢复中发挥作用。数据表明，恢复良好的患者在与受损皮质脊髓束相对的小脑半球激活方面有明显变化。恢复不佳的患者在小脑激活方面未显示出此类变化。没有其他脑区与恢复有显著相关性。有趣的是，中风后损伤同侧小脑的激活会短暂增加，与恢复是否成功无关。目前的研究表明小脑激活与中风后手部无力的行为恢复之间可能存在联系。其潜在机制尚不清楚，但可能与诸如交叉性小脑失联络等血液动力学变化或小脑在运动技能学习中的假定作用有关。
