Experimental studies on the pathomechanism of symptoms caused by the lumber canal stenosis

为了解腰椎管狭窄所致间歇性跛行的发病机制，利用与人类有相似马尾神经的猴进行动物实验研究，制作了一种特殊设计的钛制植入器，对腰椎管进行持续、定量的加压。单圈螺丝向前推进0.75 mm的圆形塑板固定在螺丝末端。每隔1周每增加1 mm加压。每隔2周行脊髓造影，观察马尾神经的形态。4只猴子植入该装置，术后随访4个月至1年3个月，但脊髓造影未见明显的马尾神经增厚和冗长。刺激肢体神经干后记录到的马尾神经诱发电位随受压程度的增加呈时间离散性。我们没有发现静脉注射前列腺素对硬脑膜管受压约65%的动物马尾诱发电位的波形有任何影响。处死一只猴子，肉眼和组织学观察马尾的变化。虽然马尾神经被挤入约为原来硬脑膜管1/3的空间，但并未观察到明显的冗余。组织学上，马尾神经髓鞘破坏、轴突变性和空泡形成。神经纤维直径较大，以损伤为主，数量减少。认为持续压迫的时间不够，因此有必要继续对动物进行脊髓造影和诱发电位的进一步观察。

To understand the pathomechanism of intermittent claudication caused by the lumbar canal stenosis, animal experimental studies using monkey which has similar cauda equina with human being were carried out.A specially designed implantable device made from titanium was fabricated to apply sustained and quantitatively controlled compression to the lumber dural tube. Single turn of the screw advanced 0.75mm of round plastic made plate which was attached at the end of the screw. Increment of the compression was carried out increasing 1mm at 1 week interval. Myelography was performed at every 2 weeks to observe the shape of the cauda equina. 4 monkeys underwent the implantation of the device and were followed up for 4 month to 1 year and 3 months, although, prominent thickening and redundancy of the cauda equina has not been revealed by myelography. Cauda equina evoked potentials recorded after stimulating the nerve trunk of lower extremities showed temporal dispersion according to the increment of the compression. We could not find any effect of intravenous injection of prostaglandin on the wave configuration of the cauda equina evoked potentials in the animal with approximately 65% compression to the dural tube.One monkey was sacrificed to observe change of the cauda equina by naked eye and histologically. Although caudae equina were squeezed in to the space which was about 1/3 of the original dural tube, prominent redundancy was not observed. Histologically, destruction of the myelin sheath, axonal degeneration and vaculation were found in the cauda equina. Nerve fibers with large diameter were dominantly damaged and decreased in number. The duration of sustained compression was regarded to be insufficient, therefore, it is deemed necessity to continue further observation of animals with myelography and evoked potentials.