Perry J
Rancho Los Amigos Medical Center, Downey, CA 90242.
Clin Orthop Relat Res. 1993 Mar(288):10-26.
The upper motor neuron lesion that causes hemiplegia impairs the patient's selective control and exposes primitive modes of muscle activation. Significant inconsistency between the clinical findings and the patient's gait may result. Dynamic electromyography revealed the primitive mechanisms leading to these inconsistencies. The rate of stretch does not differentiate spasticity from contracture, since either a quick or slow stretch frequently causes a sustained muscle response. Using knee flexion to differentiate gastrocnemius and soleus spasticity is not reliable, since the change in neurologic input with flexion may inhibit the extensor muscle's response to stretch so that the soleus is also relaxed. The change in body position from lying supine to sitting can double the intensity of soleus spasticity, and standing further increases the tone. Primitive patterns of mass extension and flexion, while voluntary, inhibit normal progression during walking. Simultaneous activation of the soleus and gastrocnemius with the knee's quadriceps causes premature ankle plantar flexion as the limb is loaded in stance. The primitive flexion synergy between the hip, knee, and ankle (dorsiflexion) inhibits terminal swing knee extension while the hip remains flexed. Consequently, surgical planning for the hemiparetic limb must rely heavily on gait analysis findings (systematic observation or by instrumentation).
导致偏瘫的上运动神经元损伤会损害患者的选择性控制能力，并暴露出原始的肌肉激活模式。临床发现与患者步态之间可能会出现显著的不一致。动态肌电图揭示了导致这些不一致的原始机制。拉伸速度无法区分痉挛和挛缩，因为快速或缓慢拉伸都常常会引起肌肉持续反应。利用膝关节屈曲来区分腓肠肌和比目鱼肌痉挛并不可靠，因为屈曲时神经输入的变化可能会抑制伸肌对拉伸的反应，从而使比目鱼肌也放松。身体姿势从仰卧位变为坐位可使比目鱼肌痉挛强度加倍，站立时则会进一步增加肌张力。原始的整体伸展和屈曲模式虽然是自主的，但会在行走过程中抑制正常进展。在肢体负重站立时，比目鱼肌和腓肠肌与膝关节股四头肌同时激活会导致踝关节过早跖屈。髋、膝和踝关节之间的原始屈曲协同作用（背屈）在髋关节仍处于屈曲状态时会抑制摆动末期膝关节伸展。因此，偏瘫肢体的手术规划必须严重依赖步态分析结果（通过系统观察或仪器测量）。
