Kawashima Noritaka, Yano Hiromi, Ohta Yuji, Nakazawa Kimitaka
Department of Movement Functions, Research Institute, National Rehabilitation Center for Persons with Disabilities, 4-1 Namiki, Tokorozawa, Saitama, 359-8555, Japan.
Exp Brain Res. 2006 Sep;174(2):342-50. doi: 10.1007/s00221-006-0470-2. Epub 2006 Jun 10.
The purpose of this study was to investigate the effects of hip proprioceptors on soleus stretch reflex excitability in standing humans. A custom-made device to stretch the ankle extensors was mounted on the lower leg portion of a gait orthosis and was used to elicit stretch reflex responses while standing. Six subjects with motor complete spinal cord injury (SCI) and six spinal intact subjects were placed in the orthosis, and stretch reflex responses were elicited when static and/or dynamic hip joint angle changes were imposed. We found that static hip extension significantly enhanced the stretch reflex responses as compared to the neutral position and the hip flexion position only in the SCI group. The EMG magnitude induced by hip extension was 142 +/- 16.6% greater than that induced by the neutral position. When the leg was dynamically swung, the reflex responses also changed with the phase of the hip angle in the SCI group; in particular, the reflex amplitude was enhanced with hip extension and in the transition phase from flexion to extension. Although the magnitude of the changes was less than that in the SCI group, a similar type of modulation was found in the normal group. Given the fact that the persons with SCI had lost the neural connection between higher nervous center and the paralyzed lower limb muscles, the mechanism underlying the present results can be attributed to the peripheral afferent input due to the hip angle changes. We concluded that hip mediated afferent input has a significant influence on the excitability modulation of the soleus stretch reflex pathway. Such neural modulation may play a role in the mechanism responsible for the phase-dependent modulation of the stretch reflex while walking.
本研究的目的是调查髋关节本体感受器对站立人体比目鱼肌牵张反射兴奋性的影响。一种定制的用于伸展踝关节伸肌的装置安装在步态矫形器的小腿部分，用于在站立时引发牵张反射反应。六名运动完全性脊髓损伤（SCI）患者和六名脊髓完整的受试者被放置在矫形器中，当施加静态和/或动态髋关节角度变化时引发牵张反射反应。我们发现，仅在SCI组中，与中立位和髋关节屈曲位相比，静态髋关节伸展显著增强了牵张反射反应。髋关节伸展诱发的肌电图幅度比中立位诱发的幅度大142±16.6%。当腿部进行动态摆动时，SCI组的反射反应也随髋关节角度的相位而变化；特别是，反射幅度在髋关节伸展时以及从屈曲到伸展的过渡阶段增强。尽管变化幅度小于SCI组，但在正常组中也发现了类似类型的调制。鉴于SCI患者失去了高级神经中枢与瘫痪下肢肌肉之间的神经连接，本研究结果的潜在机制可归因于髋关节角度变化引起的外周传入输入。我们得出结论，髋关节介导的传入输入对比目鱼肌牵张反射通路的兴奋性调制有显著影响。这种神经调制可能在步行时牵张反射的相位依赖性调制机制中起作用。
