An experimental study on chronic compression injury of the spinal cord due to kyphotic deformity.

为了评价牵引对脊髓缺血性改变对脊髓功能的影响，我们测量了成熟家兔在脊髓牵引作用下对强、弱刺激的脊髓血流和脊髓诱发电位反应。在接受约32%椎体长度牵引的动物中，弱刺激诱发电位振幅短暂增加，而强刺激诱发电位振幅缓慢下降。此时血流量下降至10ml/min/100g，提示脊髓功能障碍。对于脊髓缺血损伤的诊断，即使强刺激的幅度变化仍在安全范围内，观察弱刺激反应的幅度变化似乎也是必不可少的。采用后路（后路法）或前路（前路法）手法制备兔脊柱后凸畸形动物模型，并对脊髓施加恒压。脊柱畸形的动态压迫似乎是脊髓损伤的主要原因，而在前路手术中，静压似乎是脊髓损伤的原因。这些模型均未显示瘫痪，可能是慢性压迫性脊髓损伤初始阶段的模型。然而，在所有病例中，脊髓诱发电位的测量显示出一些电位变化。因此，这种方法对于检测慢性压迫引起的亚临床脊髓损伤非常有用。传导时间的延长在后路方法中更为明显，而振幅的下降在前路方法中更为明显。认为后路法等动态压缩容易发生脱髓鞘，而前路法等静态压缩容易引起轴突变性。脊髓损伤的质量差异可能是由压迫方式本身的差异引起的，例如后凸部分的活动是否存在，或者与每种压迫方式相关的次要因素的差异。少

In order to evaluate the influence of the traction on the spinal cord function due to ischemic changes of the spinal cord, the spinal cord blood flow and the spinal cord evoked potentials in response to strong and weak stimulation was measured in mature rabbits under spinal column traction. In animals subjected to a traction corresponding to approximately 32% of the vertebral body length, the amplitude of evoked potential in weak stimulation increased transiently, whereas the amplitude in strong stimulation declined slowly. The blood flow at this time was decreased to 10ml/min/100g, suggesting spinal cord dysfunction. For the diagnosis of spinal cord injury due to ischemia, observation of the amplitude changes in response to weak stimulus appeared to be indispensable even if the amplitude changes in strong stimulation remained within a safe range.By posterior ( posterior method ) or anterior ( anterior method ) manipulation of the rabbit spinal column, an animal model with kyphotic def … More ormity with a constant pressure on the spinal cord was prepared. The dynamic compression by the spinal deformity appeared to be the major cause of spinal cord inixiry, whereas the static pressure appeared to be responsible for the injury in the anterior method. None of these models showed paralysis, probably serving as the model for the initial stage of chronic compression spinal cord damage. However, in all cases, measurement of the spinal cord evoked potential revealed some potential changes. This method thus appeared to be very useful for the detection of subclinical spinal cord injury due to chronic compression. The prolongation of conduction time was more pronounced in the posterior method, although the decrease in amplitude appeared to be more pronounced in the anterior method. It is considered that demyelination is readily occurred on dynamic compression such as the posterior method, while the static compression as in the anterior method tends to cause axonal degeneration. Qualitative difference in spinal cord injury may be caused by the differences in the mode of compression itself, such as the presence or absence of the mobility of the kyphotic portion, or by differences in the secondary factors associated with each compression modality. Less