Spinal cord demyelination with experimental continuous compression in rat

为分析人类颈椎病、韧带骨化、脊髓肿瘤慢性压迫性脊髓病的发病机制，我们尝试以慢扩张的子宫-颈椎扩张器“危房”为压迫材料，制作大鼠脊髓连续压迫模型，并观察病变情况。在Th9椎体水平椎板下硬膜外间隙连续施加压缩材料，持续1、2、3、7、14、30和90天。采用组织化学、免疫组织化学、电镜及常规组织学对模型进行形态学观察。采用形态计量学对形态学数据进行定量分析。在该模型中，在横截面上，荒废占据了24.2%的椎管。所有大鼠在放置压缩材料后都短暂出现痉挛性截瘫，但80%的大鼠麻痹恢复。组织学上，第1天出现脊髓出血性坏死，且多局限于受压部位，即后柱。第2天白质出现海绵状变化，一直持续到第90天。海绵状改变不局限于受压部位，而是弥漫性地分布于脊髓白质中，尽管白质深层的改变比浅层更强烈。组织化学和免疫组织化学表明，白质的海绵状改变与轴突和神经丝的减少有关，但与脱髓鞘无关。薄切片甲苯胺蓝染色和电镜检查显示，侧柱的主要变化是有髓纤维轴突的变性，如水肿性肿胀，轴突丢失引起髓鞘缠结，髓鞘脱离。这些轴索病变持续观察长达90天。髓磷脂的改变，如碎裂、分裂和变薄，也见于侧柱，但频率较低。形态学测量显示髓鞘纤维直径和髓鞘厚度未见明显变化。此外，释放压力减少了退化轴突的数量。这些结果表明，使用荒废的连续脊髓压迫模型适用于慢性压迫性脊髓病的分析，提示轴突病变但脱髓鞘可能是慢性压迫性脊髓病的主要变化之一。少

To analyze the mechanism of chronic compression myelopathy in human spondylosis, ossification of ligaments, and spinal cord tumors, we tried to make a spinal cord continuous compression model in rats using uterine-cervical dilator Dilapan, which has the character of slow expanding, as compression-materials and investigated the lesions. The spine was pressured continuously with compression-material in the sublaminal epidural space at Th9 vertebral level for 1,2,3,7,14,30 and 90 days. The model was investigated morphologically, by histochemistry, immunohistochemistry, electron microscopy as well as conventional histology. The morphological data were analyzed quantiatively by morphometries.In this model, Dilapan occupied 24.2% of spinal canal in the cross sections. All rats transiently became spastic paraplegia after the placement of compression-materials, but the palsy was recovered in 80% of the rats. Histologically, at the 1st day, hemorrhagic necrosis of the spinal cord occurred, whic … More h was mostly localized in the pressured sites, i.e.posterior column. In the white matter, a spongy change appeared at 2nd day and lasted until 90th day. The spongy change was not localized at the compression site but distributed diffusely in the white matter of spinal cord, although the change was stronger in deeper parts of white matter than in superficial ones. Histochemistry and immunohistochemistry disclosed that the spongy change of white matter was associated with decrease of axon and neurofilaments, but not with demyelination. Examination of toluidine blue staining of thin sections and electron microscopy demonstrated that main change occurred in the lateral column was the degeneration of axon of myelinated fibers, such as edematous swelling, loss of axon causing myelin-tangles, and detachment from myelin sheath. These axonopathy had been continuously seen as long as 90th day. Changes of myelin, such as fragmentation, splitting, and thinning, were also seen in the lateral column but the frequency was low. Morphometry of diameters of myelinated fibers and thickness of myelin did not indicate any significant change of myelin. Furthermore, release of compression decreased the number of degenerated axons. These findings showed that continuous spinal cord compression model using Dilapan is suitable for the analysis of chronic compression myelopathy, indicating that axonopathy but demyelination may be one of the main changes in chronic compression myelopathy. Less