Taga Myriam, Hong Yoon N G, Charalambous Charalambos C, Raju Sharmila, Hayes Leticia, Lin Jing, Zhang Yian, Shao Yongzhao, Houston Michael, Zhang Yingchun, Mazzoni Pietro, Roh Jinsook, Schambra Heidi M
Department of Neurology, New York University Grossman School of Medicine, New York, New York, United States.
Department of Biomedical Engineering, University of Houston, Houston, Texas, United States.
J Neurophysiol. 2024 Dec 1;132(6):1917-1936. doi: 10.1152/jn.00301.2024. Epub 2024 Nov 6.
After corticospinal tract (CST) stroke, several motor deficits can emerge in the upper extremity (UE), including diminished muscle strength, motor control, and muscle individuation. Both the ipsilesional CST and contralesional corticoreticulospinal tract (CReST) innervate the paretic UE, but their relationship to motor behaviors after stroke remains uncertain. In this cross-sectional study of 14 chronic stroke and 27 healthy subjects, we examined two questions: whether the ipsilesional CST and contralesional CReST differentially relate to chronic motor behaviors in the paretic arm and hand and whether the severity of motor deficits differs by proximal versus distal location. In the paretic biceps and first dorsal interosseous muscles, we used transcranial magnetic stimulation to measure the projection strengths of the ipsilesional CST and contralesional CReST. We also used quantitative testing to measure strength, motor control, and muscle individuation in each muscle. We found that stroke subjects had muscle strength comparable to healthy subjects but poorer motor control and muscle individuation. In both paretic muscles, stronger ipsilesional CST projections related to better motor control, whereas stronger contralesional CReST projections related to better muscle strength. Stronger CST projections related to better individuation in the biceps alone. The severity of motor control and individuation deficits was comparable in the arm and hand. These findings suggest that the ipsilesional CST and contralesional CReST have specialized but complementary roles in motor behaviors of the paretic arm and hand. They also suggest that deficits in motor control and muscle individuation are not segmentally biased, underscoring the functional extent and efficacy of these pathways. The corticospinal (CST) and corticoreticulospinal (CReST) tracts are two major descending motor pathways. We examined their relationships to motor behaviors in paretic arm and hand muscles in chronic stroke. Stronger ipsilesional CST projections related to better motor control, whereas stronger contralesional CReST projections related to better muscle strength. Stronger CST projections are also uniquely related to better biceps individuation. These findings support the notion of specialized but complementary contributions of these pathways to human motor function.
皮质脊髓束（CST）中风后，上肢（UE）可能会出现多种运动功能障碍，包括肌肉力量减弱、运动控制能力下降和肌肉分离能力受损。同侧CST和对侧皮质网状脊髓束（CReST）均支配患侧上肢，但它们与中风后运动行为的关系仍不明确。在这项对14名慢性中风患者和27名健康受试者的横断面研究中，我们探讨了两个问题：同侧CST和对侧CReST与患侧手臂和手部的慢性运动行为之间是否存在差异关系，以及运动功能障碍的严重程度在近端和远端部位是否有所不同。在患侧肱二头肌和第一背侧骨间肌中，我们使用经颅磁刺激来测量同侧CST和对侧CReST的投射强度。我们还使用定量测试来测量每块肌肉的力量、运动控制能力和肌肉分离能力。我们发现，中风患者的肌肉力量与健康受试者相当，但运动控制能力和肌肉分离能力较差。在两块患侧肌肉中，同侧CST投射越强，运动控制能力越好，而对侧CReST投射越强，肌肉力量越好。仅在肱二头肌中，较强的CST投射与更好的肌肉分离能力有关。手臂和手部的运动控制和分离能力障碍的严重程度相当。这些发现表明，同侧CST和对侧CReST在患侧手臂和手部的运动行为中具有专门但互补的作用。它们还表明，运动控制和肌肉分离能力的障碍并非节段性偏向，这突出了这些通路的功能范围和效能。皮质脊髓束（CST）和皮质网状脊髓束（CReST）是两条主要的下行运动通路。我们研究了它们与慢性中风患者患侧手臂和手部肌肉运动行为的关系。同侧CST投射越强，运动控制能力越好，而对侧CReST投射越强，肌肉力量越好。较强的CST投射还与更好的肱二头肌分离能力独特相关。这些发现支持了这些通路对人类运动功能具有专门但互补作用的观点。
