Subramanian Sandeep K, Feldman Anatol G, Levin Mindy F
Département de Neurosciences, Université de Montréal , Montreal, Quebec , Canada.
Feil-Oberfeld Research Centre, Jewish Rehabilitation Hospital (research site of the Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal) , Laval, Quebec , Canada.
J Neurophysiol. 2018 Jan 1;119(1):5-20. doi: 10.1152/jn.00362.2017. Epub 2017 Sep 13.
Previous motor learning studies based on adapting movements of the hemiparetic arm in stroke subjects have not accounted for spasticity occurring in specific joint ranges (spasticity zones), resulting in equivocal conclusions about learning capacity. We compared the ability of participants with stroke to rapidly adapt elbow extension movements to changing external load conditions outside and inside spasticity zones. Participants with stroke ( n = 12, aged 57.8 ± 9.6 yr) and healthy age-matched controls ( n = 8, 63.5 ± 9.1 yr) made rapid 40°-50° horizontal elbow extension movements from an initial (3°) to a final (6°) target. Sixteen blocks (6-10 trials/block) consisting of alternating loaded (30% maximal voluntary contraction) and nonloaded trials were made in one (controls) or two sessions (stroke; 1 wk apart). For the stroke group, the tonic stretch reflex threshold angle at which elbow flexors began to be activated during passive elbow extension was used to identify the beginning of the spasticity zone. The task was repeated in joint ranges that did or did not include the spasticity zone. Error correction strategies were identified by the angular positions before correction and compared between groups and sessions. Changes in load condition from no load to load and vice versa resulted in undershoot and overshoot errors, respectively. Stroke subjects corrected errors in 1-4 trials compared with 1-2 trials in controls. When movements did not include the spasticity zone, there was an immediate decrease in the number of trials needed to restore accuracy, suggesting that the capacity to learn may be preserved after stroke but masked by the presence of spasticity. NEW & NOTEWORTHY When arm movements were made outside, instead of inside, the range affected by spasticity, there was an immediate decrease in the number of trials needed to restore accuracy in response to a change in the external load. This suggests that motor learning processes may be preserved in patients with stroke but masked by the presence of spasticity in specific joint ranges. This has important implications for designing rehabilitation interventions predicated on motor learning principles.
以往基于中风患者偏瘫侧手臂运动适应性的运动学习研究，未考虑特定关节活动范围（痉挛区）出现的痉挛情况，导致关于学习能力的结论模棱两可。我们比较了中风患者在痉挛区内外快速使肘部伸展运动适应外部负荷变化的能力。中风患者（n = 12，年龄57.8±9.6岁）和年龄匹配的健康对照者（n = 8，63.5±9.1岁）进行从初始（3°）到最终（6°）目标的快速40°-50°水平肘部伸展运动。对照组进行1组、中风组进行2组（间隔1周）由交替加载（30%最大自主收缩）和无负荷试验组成的16个试验块（每组6-10次试验）。对于中风组，在被动肘部伸展过程中肘部屈肌开始被激活时的强直性牵张反射阈值角度用于确定痉挛区的起点。该任务在包含或不包含痉挛区的关节活动范围内重复进行。通过校正前的角度位置确定误差校正策略，并在组间和组内进行比较。负荷条件从无负荷变为有负荷以及反之，分别导致运动不足和运动过度误差。中风患者在1-4次试验中校正误差，而对照组在1-2次试验中校正误差。当运动不包括痉挛区时，恢复准确性所需的试验次数立即减少，这表明中风后学习能力可能保留，但被痉挛的存在所掩盖。新发现且值得注意的是，当手臂运动在受痉挛影响的范围之外而非之内进行时，响应外部负荷变化恢复准确性所需的试验次数立即减少。这表明运动学习过程在中风患者中可能保留，但被特定关节活动范围内的痉挛存在所掩盖。这对于基于运动学习原则设计康复干预具有重要意义。
