Turpin Nicolas A, Feldman Anatol G, Levin Mindy F
Department of Neuroscience, Montreal, QC, Canada; Institute of Biomedical Engineering, University of Montreal, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal, QC, Canada.
School of Physical and Occupational Therapy, McGill University, Montreal, QC, Canada; Center for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal, QC, Canada.
Clin Neurophysiol. 2017 Oct;128(10):1891-1897. doi: 10.1016/j.clinph.2017.07.411. Epub 2017 Aug 3.
Voluntary movements post-stroke are affected by abnormal muscle activation due to exaggerated stretch reflexes (SRs). We examined the ability of post-stroke subjects to regulate SRs in spastic muscles.
Elbow flexor and extensor EMGs and joint angle were recorded in 13 subjects with chronic post-stroke spasticity. Muscles were either stretched passively (relaxed arm) or actively (antagonist contraction) at different velocities. Velocity-dependent SR thresholds were defined as angles where stretched muscle EMG exceeded 3SDs of baseline. Sensitivity of SRs to stretch velocity was defined as µ. The regression through thresholds was interpolated to zero velocity to obtain the tonic SR threshold (TSRT) angle.
Compared to passive stretches, TSRTs during active motion occurred at longer muscle lengths (i.e., increased in flexors and decreased in extensors by 10-40°). Values of μ increased by 1.5-4.0. Changes in flexor TSRTs during active compared to passive stretches were correlated with clinical spasticity (r=-0.68) and arm motor impairment (r=0.81).
Spasticity thresholds measured at rest were modulated during active movement. Arm motor impairments were related to the ability to modulate SR thresholds between the two states rather than to passive-state values.
Relationship between spasticity and movement disorders may be explained by deficits in SR threshold range of regulation and modifiability, representing a measure of stroke-related sensorimotor deficits.
中风后的自主运动受到由于夸张的牵张反射（SRs）导致的异常肌肉激活的影响。我们研究了中风后受试者调节痉挛肌肉中SRs的能力。
记录了13名患有慢性中风后痉挛的受试者的肘屈肌和伸肌肌电图以及关节角度。肌肉分别以不同速度进行被动拉伸（手臂放松）或主动拉伸（拮抗肌收缩）。速度依赖性SR阈值定义为拉伸肌肉肌电图超过基线3标准差时的角度。SRs对拉伸速度的敏感性定义为μ。通过阈值的回归被内插到零速度以获得强直SR阈值（TSRT）角度。
与被动拉伸相比，主动运动期间的TSRTs出现在更长的肌肉长度处（即，屈肌增加，伸肌减少10 - 40°）。μ值增加了1.5 - 4.0。与被动拉伸相比，主动运动期间屈肌TSRTs的变化与临床痉挛（r = -0.68）和手臂运动障碍（r = 0.81）相关。
静息时测量的痉挛阈值在主动运动期间受到调节。手臂运动障碍与在两种状态之间调节SR阈值的能力有关，而不是与被动状态值有关。
痉挛与运动障碍之间的关系可能由SR阈值调节范围和可修改性的缺陷来解释，这代表了中风相关的感觉运动缺陷的一种度量。
