Hill Nayo M, Dewald Julius P A
Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States.
Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States.
Front Hum Neurosci. 2020 Oct 16;14:590198. doi: 10.3389/fnhum.2020.590198. eCollection 2020.
Hemiparetic stroke in adulthood often results in the grouped movement pattern of the upper extremity flexion synergy thought to arise from an increased reliance on cortico-reticulospinal pathways due to a loss of lateral corticospinal projections. It is well established that the flexion synergy induces reaching constraints in individuals with adult-onset hemiplegia. The expression of the flexion synergy in individuals with brain injuries onset earlier in the lifespan is currently unknown. An early unilateral brain injury occurring prior to six months post full-term may preserve corticospinal projections which can be used for independent joint control and thus minimizing the expression of the flexion synergy. This study uses kinematics of a ballistic reaching task to evaluate the expression of the flexion synergy in individuals with pediatric hemiplegia (PH) ages six to seventeen years. Fifteen individuals with brain injuries before birth ( = 8) and around full-term ( = 7) and nine age-matched controls with no known neurological impairment completed a set of reaches in an admittance controlled robotic device. Descending drive, and the possible expression of the upper extremity flexion synergy, was modulated by increasing shoulder abduction loading. Individuals with early-onset PH achieved lower peak velocities when reaching with the paretic arm compared to controls; however, no differences in reaching distance were found between groups. Relative maintenance in reaching seen in individuals with early brain injuries highlights minimal expression of the flexion synergy. We interpret this conservation of independent control of the paretic shoulder and elbow as the use of more direct corticospinal projections instead of indirect cortico-reticulospinal pathways used in individuals with adult-onset hemiplegia.
成年期的偏瘫性中风常导致上肢屈曲协同运动模式，这种模式被认为是由于外侧皮质脊髓投射丧失，对皮质-网状脊髓通路的依赖增加所致。众所周知，屈曲协同运动会给成年期偏瘫患者的伸手动作带来限制。目前尚不清楚在生命早期发生脑损伤的个体中屈曲协同运动的表现情况。足月后六个月之前发生的早期单侧脑损伤可能会保留皮质脊髓投射，这些投射可用于独立的关节控制，从而使屈曲协同运动的表现降至最低。本研究采用弹道式伸手任务的运动学方法，评估6至17岁小儿偏瘫（PH）患者的屈曲协同运动表现。15名出生前（n = 8）和足月左右（n = 7）脑损伤的个体以及9名年龄匹配、无已知神经功能障碍的对照者在一个导纳控制的机器人设备中完成了一组伸手动作。通过增加肩部外展负荷来调节下行驱动以及上肢屈曲协同运动的可能表现。与对照组相比，早发性小儿偏瘫患者患侧手臂伸手时达到的峰值速度较低；然而，两组之间的伸手距离没有差异。早期脑损伤个体在伸手动作中的相对维持情况表明屈曲协同运动的表现 minimal。我们将患侧肩部和肘部独立控制的这种保留解释为使用了更直接的皮质脊髓投射，而非成年期偏瘫患者所使用的间接皮质-网状脊髓通路。 （注：原文中“minimal expression of the flexion synergy”处“minimal”疑似有误，结合语境推测可能是“最小化的表现”，译文按此理解翻译，但需注意原文可能存在问题。）
