Sun Yao, Ledwell Noah M H, Boyd Lara A, Zehr E Paul
Rehabilitation Neuroscience Laboratory, University of Victoria, Victoria, BC, V8P5C2, Canada.
Human Discovery Science, International Collaboration on Repair Discovery (ICORD), Vancouver, BC, V5Z1M9, Canada.
Exp Brain Res. 2018 Jul;236(7):2009-2021. doi: 10.1007/s00221-018-5275-6. Epub 2018 May 5.
Stroke induces bilateral neurological impairment and muscle weakness yielding neurologically more (MA; paretic) and less affected (LA; non-paretic) sides. "Cross-education" refers to training one side of the body to increase strength in the same muscles on the untrained side. Past work showed dorsiflexion training of the LA side produced bilateral strength increases after stroke. The current study explored the presence and extent of cross-education after arm strength training in chronic stroke. Twenty-four chronic stroke participants completed 5 weeks of maximal wrist extension training using their LA arm. Maximal voluntary contraction force, arm motor impairment and functional performance were measured before and after training. Both spinal cord plasticity (n = 12: reciprocal inhibition and cutaneous reflexes, University of Victoria) and cortical plasticity (n = 12: cortical silent period, short-interval intracortical inhibition, intracortical facilitation and transcallosal inhibition, University of British Columbia) were assessed. Five weeks after training, 20 participants completed a follow-up maximal wrist extension retention test. LA wrist extension force increased 42% and MA by 35%. Strength gains were maintained in the follow-up test. Clinically meaningful increases in Fugl-Meyer scores were noted in four participants. Muscle activation was correlated with cutaneous reflex amplitudes after training in the MA arm. LA cortical silent period and transcallosal inhibition from both hemispheres significantly decreased after training. This study shows that high-intensity training with the neurologically less affected "non-paretic" arm can improve strength bilaterally and alter both spinal and cortical plasticity. The extent to which this plasticity can be enhanced or functionally exploited remains to be examined.
中风会导致双侧神经功能障碍和肌肉无力，从而产生神经功能受影响较大（MA；患侧）和较小（LA；健侧）的两侧。“交叉训练”是指训练身体的一侧以增强未训练侧相同肌肉的力量。过去的研究表明，中风后对LA侧进行背屈训练可使双侧力量增加。本研究探讨了慢性中风患者进行手臂力量训练后交叉训练的存在情况和程度。24名慢性中风参与者使用其LA侧手臂完成了为期5周的最大程度腕伸展训练。在训练前后测量了最大自主收缩力、手臂运动障碍和功能表现。同时评估了脊髓可塑性（n = 12：交互抑制和皮肤反射，维多利亚大学）和皮质可塑性（n = 12：皮质静息期、短间隔皮质内抑制、皮质内易化和胼胝体间抑制，英属哥伦比亚大学）。训练5周后，20名参与者完成了一项后续的最大程度腕伸展保持测试。LA侧腕伸展力增加了42%，MA侧增加了35%。力量增加在后续测试中得以维持。四名参与者的Fugl-Meyer评分有临床意义的提高。训练后，MA侧手臂的肌肉激活与皮肤反射幅度相关。训练后，LA侧皮质静息期以及来自两侧半球的胼胝体间抑制均显著降低。本研究表明，对神经功能受影响较小的“健侧”手臂进行高强度训练可双侧改善力量，并改变脊髓和皮质的可塑性。这种可塑性能够增强或在功能上加以利用的程度仍有待研究。
