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目的:探讨颈脊髓慢性压迫动物模型的建立方法及可行性评估。方法:将9只绵羊分为对照组(A组)、1个月组(B组)和3个月组(C组)。经颈前路手术将新型注射压迫系统的致压球囊置入C4/5椎间隙并固定,将注射阀埋于颈后皮下。A组术后不注射碘海醇,B、C组术后每周经皮向注射阀注射0.1ml碘海醇,使球囊缓慢膨胀,对颈脊髓产生慢性压迫。每4周于全麻下行颈椎X线、CT和MRI检查。每次注射造影剂后和检查前后用Tarlov评分法对动物进行行为学评价。终止观察时取压迫节段脊髓进行病理观察及电镜观察超微结构变化。应用单因素方差分析评估不同组实验动物行为学的差异,用Pearson相关系数分析各观测参数的相关性。结果:A组各时间点Tarlov评分均为5分。B组及C组每次注射造影剂前后Tarlov评分不变。终止观察时B组实验动物平均椎管侵占率为54.6%,Tarlov评分1只4分,2只5分;C组实验动物平均椎管侵占率67.6%,Tarlov评分1只2分,2只3分。肉眼可见B组受压节段脊髓变扁,C组明显凹陷;病理学检查见B组受压节段脊髓前角内神经元数量减少,胞体周围间隙增大,尼氏体减少,白质轻度脱髓鞘,部分轴突空泡变性;C组白质出现片状脱髓鞘区和空泡变性,灰质内多量神经元变性,可见核固缩、尼氏体减少或消失。电镜下B组神经元胞质内粗面内质网轻度扩张,部分线粒体肿胀,轴突空泡变性,形态不规则,髓鞘松解,部分轴突髓鞘脱失;C组神经元可见胞膜崩解,核固缩,粗面内质网明显扩张,核糖体脱失,线粒体广泛空泡变性,髓鞘崩解,轴突肿胀,基质致密,部分轴突消失。A组未见异常组织学改变。结论:术后实验动物行为学、影像学和组织学检查符合慢性压迫性颈脊髓病特点,新型注射压迫系统可以辅助建立稳定、可靠的慢性颈脊髓压迫动物模型。
Objective: To investigate the method and feasibility of animal models of chronic cervical spinal cord compression. Methods: Nine sheep were divided into control group (A group), 1 month group (B group) and 3 months group (C group). Anterior cervical surgery will be a new type of compression system into the compression balloon C4 / 5 intervertebral space and fixed, the injection valve buried in the neck after the skin. In group A, iohexol was not injected after operation. In group B and group C, 0.1 mL of iohexol was percutaneously injected into the injection valve per week, causing the balloon to expand slowly, causing chronic compression to the cervical spinal cord. Cervical X-ray, CT and MRI were performed every 4 weeks under general anesthesia. Behavioral evaluation of animals was performed with Tarlov score after each injection of contrast agent and before and after the test. At termination of observation, the spinal cord of the compression segment was taken for pathological observation and ultrastructural changes by electron microscopy. One-way analysis of variance (ANOVA) was used to assess the differences in behavior between different groups of experimental animals. Pearson correlation coefficients were used to analyze the correlation between the observed parameters. Results: The Tarlov score of each group was 5 points at each time point. Tarlov scores before and after each injection of contrast agent in Group B and Group C remained unchanged. At the end of observation, the average spinal canal invasion rate of Group B animals was 54.6%, Tarlov score was 1 and 4, and 2 and 5 respectively. In Group C, the average spinal canal invasion rate was 67.6%, Tarlov score was 1 and 2 were 3 Minute. Macroscopically, the spinal cord of the compression segment of group B became flattened and the group C was significantly depressed. The number of neurons in the anterior horn of the spinal cord in group B was reduced by pathological examination, the clearance around the cell body was increased, the Nissl body was reduced and the white matter was mild Demyelination, degeneration of some axons; C group white demyelination and vacuolar degeneration, a large number of neurons within the gray matter degeneration, visible nuclear pyknosis, Nisshin reduce or disappear. Under electron microscope, the rough endoplasmic reticulum in group B was mildly dilated, some of mitochondria were swollen, the axonal degeneration, irregular shape, myelin sheath loosening and partial axon demyelination. The neurons in group C were visible Cell membrane disintegration, nuclear pyknosis, rough endoplasmic reticulum expansion, ribosome loss, mitochondria extensive vacuolar degeneration, myelin disintegration, axonal swelling, matrix density, part of the axon disappeared. No abnormal histological changes were found in group A. CONCLUSION: Postoperative behavioral, imaging and histological examination of experimental animals are consistent with the characteristics of chronic cervical myelopathy. A new injection compression system can help establish a stable and reliable animal model of chronic cervical spinal cord compression.