Peng Yanmin, Liu Jingchun, Hua Minghui, Liang Meng, Yu Chunshui
Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China.
School of Medical Imaging, Tianjin Medical University, Tianjin, China.
Front Neurol. 2019 Aug 21;10:909. doi: 10.3389/fneur.2019.00909. eCollection 2019.
Interhemispheric imbalance may provide a framework for developing new strategies to facilitate post-stroke motor recovery especially for patients in chronic stage. Using effective connectivity analysis, we aimed to investigate interactions between the bilateral primary motor cortices (M1) and their correlations with motor function and M1-related structural and functional changes in well-recovered patients with chronic subcortical ischemic stroke. Twenty subcortical stroke patients and 20 normal controls underwent multimodal magnetic resonance imaging (MRI) examinations. During the movement of the affected hand, functional MRI was used to calculate the M1 activation and M1-M1 effective connectivity. Diffusion tensor imaging was used to compute the fractional anisotropy (FA) of the affected corticospinal tract (CST) and M1-M1 anatomical connection. After intergroup comparisons, we tested whether the altered M1-M1 effective connectivity was correlated with the motor function, M1 activation and FA of the affected CST and M1-M1 anatomical connection in patients. Compared to normal controls, stroke patients exhibited increased excitatory effective connectivity from ipsilesional to contralesional M1 and increased ipsilesional M1 activation; however, they showed reduced FA values in the affected CST and M1-M1 anatomical connection. The increased effective connectivity was positively correlated with motor score and the FA of the M1-M1 anatomical connection, but not with the M1 activation or the FA of the affected CST in these patients. These findings suggest that the enhancement of M1-M1 effective connectivity from ipsilesional to contralesional hemisphere depends on the integrity of the underlying M1-M1 anatomical connection (i.e., less deficits of the M1-M1 anatomical connection, greater enhancement of the corresponding effective connectivity), and such M1-M1 effective connectivity enhancement plays a supportive role in motor function in chronic subcortical stroke.
半球间失衡可能为制定促进中风后运动恢复的新策略提供一个框架，特别是对于慢性期患者。通过有效的连通性分析，我们旨在研究双侧初级运动皮层（M1）之间的相互作用，以及它们与慢性皮质下缺血性中风恢复良好患者的运动功能、M1相关结构和功能变化的相关性。20名皮质下中风患者和20名正常对照者接受了多模态磁共振成像（MRI）检查。在患侧手运动期间，功能MRI用于计算M1激活和M1-M1有效连通性。扩散张量成像用于计算患侧皮质脊髓束（CST）和M1-M1解剖连接的分数各向异性（FA）。在组间比较后，我们测试了改变的M1-M1有效连通性是否与患者的运动功能、M1激活、患侧CST的FA以及M1-M1解剖连接相关。与正常对照相比，中风患者表现出从患侧M1到对侧M1的兴奋性有效连通性增加以及患侧M1激活增加；然而，他们患侧CST和M1-M1解剖连接的FA值降低。有效连通性增加与运动评分和M1-M1解剖连接的FA呈正相关，但与这些患者的M1激活或患侧CST的FA无关。这些发现表明，从患侧半球到对侧半球的M1-M1有效连通性增强取决于潜在的M1-M1解剖连接的完整性（即，M1-M1解剖连接缺陷越少，相应有效连通性增强越大），并且这种M1-M1有效连通性增强在慢性皮质下中风的运动功能中起支持作用。
