Powers R K, Marder-Meyer J, Rymer W Z
Sensory-Motor Performance Program, Rehabilitation Institute of Chicago, IL 60611.
Ann Neurol. 1988 Feb;23(2):115-24. doi: 10.1002/ana.410230203.
The relative contributions of variations in stretch reflex threshold and total joint stiffness to changes in stretch-evoked torque were assessed in the spastic elbow muscles of 14 hemiparetic spastic subjects. For a given subject, variations in torque, measured after a constant angular deflection, were mediated largely by changes in stretch reflex threshold, rather than by changes in reflex stiffness. Between-subject comparisons were sensitive to stiffness differences between limbs, but reflex thresholds were still broadly correlated with torque magnitude, suggesting that reductions in stretch reflex threshold are uniformly present in spastic muscles. These findings, coupled with the apparent similarity of reflex stiffness estimates in voluntarily activated spastic and normal muscles, suggest that the central disturbance in spasticity is a reduction in the threshold of the stretch reflex, without a significant enhancement of reflex gain.
在14名偏瘫痉挛患者的痉挛性肘部肌肉中，评估了牵张反射阈值变化和总关节刚度变化对牵张诱发扭矩变化的相对贡献。对于给定的受试者，在恒定角度偏转后测量的扭矩变化主要由牵张反射阈值的变化介导，而不是由反射刚度的变化介导。受试者之间的比较对肢体之间的刚度差异敏感，但反射阈值仍与扭矩大小广泛相关，这表明牵张反射阈值的降低在痉挛性肌肉中普遍存在。这些发现，再加上在自愿激活的痉挛性肌肉和正常肌肉中反射刚度估计值的明显相似性，表明痉挛的中枢干扰是牵张反射阈值的降低，而反射增益没有显著增强。
