颈脊髓慢性压迫模型的建立及其病理改变

Establishing a chronic compression model of cervical spinal cord and studying the pathological changes

目的:建立与临床相近的颈脊髓慢性压迫动物实验模型,观察其MRI和病理改变。方法:56只20～24个月的雄性山羊(体重13～17kg,平均15kg),随机分为对照组(8只)、颈脊髓压迫3个月组(24只)和6个月组(24只)。均经前路通过C5置入钛合金螺钉,后路在相应的椎板下置入钛合金钢板,不直接压迫颈脊髓,当羊颈椎活动时才会对脊髓逐渐造成压迫和损害。对照组山羊螺钉和钢板置入后立即取出。在置入螺钉和钢板后3个月和6个月时对山羊进行运动功能评分,颈椎拍X线片和进行MRI检查,然后处死山羊取颈髓做病理检查。对照组山羊做相同检查。结果:对照组山羊的运动功能评分(平均5.0±0.0分)和影像学检查均没有明显变化。而脊髓压迫3个月和6个月组山羊运动功能评分分别为3.8±0.6分和2.7±1.2分,与对照组比较P<0.05;MRIT2加权矢状位和冠状位像均可见受压部位脊髓白质和灰质密度明显增加。病理检查发现受压3个月组在脊髓前角和后角出现神经原减少和坏死,且压迫6个月组较压迫3个月变化更为明显。结论:新的颈脊髓慢性压迫动物实验模型容易复制,通过该模型可较好地观察脊髓受压不同时间的影像学和病理改变。

Objective：To establish a kind of animal experimental model with typical clinical characteristics of cervical compressive myelopathy and study the changes of MRI and pathology.Method：Fifty six 20-24 months old goats （body weights：13-17kg,mean：lSkg） were randomly divided into three groups in this study：control group（n=8）,compression 3 months（n=24） and 6 months（n=24） groups.In this model,the compression was given to a single intervertebral space（CS） using titanium screw from the front and a titanium plate from the dorsal side,the changes of clinical characteristics,MRI and pathology were studied.Result：In the control group,the motor function was normal.In the compression 3 and 6 months group,by using the modification of Tarlov＇s classification,the motor function was 3.8±0.6 and 2.7±1.2 respectively.On MRI T2-weighted sagittal images,hyperintensity area was found in the medullary of the compressed area,on T2-weighted axial images, intensities of the white and gray matters on the compressed area were higher than those in the areas without compression.Histologically,the gray and white matter was associated with the compression of the anterior horn and posterior horn,it was also associated with the compression time.When spinal cord were compressed 3 months,the nerve cells decreased and some of them were necrosis,axonal degeneration and mild demyelination.After spinal cord were compressed 6 months,the present changes were more severe.Conclusion： The new kind of animal experimental model can be duplicated efficiently.Using this model,the destructive pathologic changes in the chronic compression spinal cord can be noticed.