Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL, USA.
J Neurophysiol. 2013 Jul;110(2):418-30. doi: 10.1152/jn.00573.2012. Epub 2013 May 1.
This study characterizes tonic and phasic stretch reflex and stiffness and viscosity changes associated with spastic hemiparesis. Perturbations were applied to the ankle of 27 hemiparetic and 36 healthy subjects under relaxed or active contracting conditions. A nonlinear delay differential equation model characterized phasic and tonic stretch reflex gains, elastic stiffness, and viscous damping. Tendon reflex was characterized with reflex gain and threshold. Reflexively, tonic reflex gain was increased in spastic ankles at rest (P < 0.038) and was not regulated with muscle contraction, indicating impaired tonic stretch reflex. Phasic-reflex gain in spastic plantar flexors was higher and increased faster with plantar flexor contraction (P < 0.012) than controls (P < 0.023) and higher in dorsi-flexors at lower torques (P < 0.038), primarily because of its increase at rest (P = 0.045), indicating exaggerated phasic stretch reflex especially in more spastic plantar flexors, which showed higher phasic stretch reflex gain than dorsi-flexors (P < 0.032). Spasticity was associated with increased tendon reflex gain (P = 0.002) and decreased threshold (P < 0.001). Mechanically, stiffness in spastic ankles was higher than that in controls across plantar flexion/dorsi-flexion torque levels (P < 0.032), and the more spastic plantar flexors were stiffer than dorsi-flexors at comparable torques (P < 0.031). Increased stiffness in spastic ankles was mainly due to passive stiffness increase (P < 0.001), indicating increased connective tissues/shortened fascicles. Viscous damping in spastic ankles was increased across the plantar flexion torque levels and at lower dorsi-flexion torques, reflecting increased passive viscous damping (P = 0.033). The more spastic plantar flexors showed higher viscous damping than dorsi-flexors at comparable torque levels (P < 0.047). Simultaneous characterizations of reflex and nonreflex changes in spastic hemiparesis may help to evaluate and treat them more effectively.
本研究描述了与痉挛性偏瘫相关的紧张性和相位拉伸反射以及僵硬和粘性变化。在放松或主动收缩条件下，向 27 名偏瘫患者和 36 名健康受试者的脚踝施加了扰动。非线性时滞微分方程模型描述了相位和紧张性拉伸反射增益、弹性刚度和粘性阻尼。用反射增益和阈值来描述肌腱反射。在痉挛性踝关节中，紧张性反射增益在休息时增加（P<0.038），并且不受肌肉收缩的调节，表明紧张性拉伸反射受损。痉挛性跖屈肌的相位反射增益较高，并且随着跖屈肌收缩的增加更快（P<0.012）比对照组（P<0.023），并且在较低的扭矩下在背屈肌中更高（P<0.038），主要是因为其在休息时增加（P=0.045），表明相位拉伸反射过度，特别是在更痉挛的跖屈肌中，其相位拉伸反射增益高于背屈肌（P<0.032）。痉挛与肌腱反射增益增加（P=0.002）和阈值降低（P<0.001）有关。在机械方面，痉挛性踝关节的刚度高于对照组在整个跖屈/背屈扭矩水平（P<0.032），并且在可比扭矩下更痉挛的跖屈肌比背屈肌更硬（P<0.031）。痉挛性踝关节的刚度增加主要是由于被动刚度增加（P<0.001），表明结缔组织/缩短的束增加。在整个跖屈扭矩水平和较低的背屈扭矩下，痉挛性踝关节的粘性阻尼增加，反映了被动粘性阻尼的增加（P=0.033）。在可比扭矩水平下，更痉挛的跖屈肌比背屈肌具有更高的粘性阻尼（P<0.047）。痉挛性偏瘫中反射和非反射变化的同时描述可能有助于更有效地评估和治疗它们。
