Runnalls Keith D, Anson Greg, Wolf Steven L, Byblow Winston D
Movement Neuroscience Laboratory, Department of Sport and Exercise Science, University of Auckland, Auckland, New Zealand Centre for Brain Research, University of Auckland, Auckland, New Zealand.
Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, Georgia Atlanta VA Center of Excellence in Visual and Neurocognitive Rehabilitation, Atlanta, Georgia.
Physiol Rep. 2014 Dec 11;2(12). doi: 10.14814/phy2.12183. Print 2014 Dec 1.
Partial weight support may hold promise as a therapeutic adjuvant during rehabilitation after stroke by providing a permissive environment for reducing the expression of abnormal muscle synergies that cause upper limb impairment. We explored the neurophysiological effects of upper limb weight support in 13 healthy young adults by measuring motor-evoked potentials (MEPs) from transcranial magnetic stimulation (TMS) of primary motor cortex and electromyography from anterior deltoid (AD), biceps brachii (BB), extensor carpi radialis (ECR), and first dorsal interosseous (FDI). Five levels of weight support, varying from none to full, were provided to the arm using a commercial device (Saebo Mobile Arm Support). For each level of support, stimulus-response (SR) curves were derived from MEPs across a range of TMS intensities. Weight support affected background EMG activity in each of the four muscles examined (P < 0.0001 for each muscle). Tonic background activity was primarily reduced in the AD. Weight support had a differential effect on the size of MEPs across muscles. After curve fitting, the SR plateau for ECR increased at the lowest support level (P = 0.004). For FDI, the SR plateau increased at the highest support level (P = 0.0003). These results indicate that weight support of the proximal upper limb modulates corticomotor excitability across the forearm and hand. The findings support a model of integrated control of the upper limb and may inform the use of weight support in clinical settings.
部分体重支撑可能有望成为中风后康复过程中的一种治疗辅助手段，因为它能提供一个宽松的环境，以减少导致上肢功能障碍的异常肌肉协同作用的表现。我们通过测量来自初级运动皮层的经颅磁刺激（TMS）诱发的运动诱发电位（MEP）以及三角肌前束（AD）、肱二头肌（BB）、桡侧腕伸肌（ECR）和第一背侧骨间肌（FDI）的肌电图，探讨了13名健康年轻成年人上肢体重支撑的神经生理效应。使用商用设备（Saebo移动手臂支撑）为手臂提供从无到完全的五个体重支撑水平。对于每个支撑水平，在一系列TMS强度下从MEP得出刺激-反应（SR）曲线。体重支撑影响了所检查的四块肌肉中每块肌肉的背景肌电活动（每块肌肉P < 0.0001）。AD的紧张性背景活动主要降低。体重支撑对不同肌肉的MEP大小有不同影响。曲线拟合后，ECR的SR平台在最低支撑水平时增加（P = 0.004）。对于FDI，SR平台在最高支撑水平时增加（P = 0.0003）。这些结果表明上肢近端的体重支撑调节了前臂和手部的皮质运动兴奋性。这些发现支持了上肢综合控制模型，并可能为临床环境中体重支撑的使用提供参考。
