神经根慢性嵌压损伤的动物模型建立

The animal model of chronic compressive injury of spinal nerve roots

目的:建立一种由自身骨性增生造成神经根慢性嵌压损伤的动物模型,为相关实验提供造模方法。方法:30只健康家猫,手术显露右侧C7、C8和L5、L6神经根及其椎间孔内口,用牙髓钻破坏椎间孔周围骨皮质后,将“V”形松质骨块沿骨壁嵌于神经根通道的骨性管道内及侧隐窝后方,左侧做正常对照。在造模术前和术后第2、4、8、12、24周行磁刺激运动诱发电位(MEP)检测,每次随机选6只,4～5只行影像学检查,以确定神经根通道的狭窄程度和神经根受压状态,6只均做病理组织学检查和椎间孔截面积测量。结果:术后早期实验侧肢体出现行为异常;而后有不同程度肌萎缩;后期部分肢体远端出现溃疡。影像学检查随着嵌压时间延长,实验侧椎间孔骨痂增多,狭窄加重,神经根受压变形,椎间孔骨性截面积8周后明显减小,与对照侧比较有显著性差异。术后2周,神经根组织学检查主要表现为神经束膜、内膜的水肿,髓鞘肿胀;4周后发生节段性脱髓鞘;8周时神经轴突增粗、断裂,远端瓦勒氏变性;12周后变性神经结构崩解、吸收,形成空洞;24周时整个神经干纤维化。术后4周时实验侧MEP开始出现潜伏期延长;8周时伴有波形分化不清;12周波幅明显下降;24周MEP的引出困难,部分电位消失。结论:采用椎间孔内自体松质骨植入,造成神经根慢性嵌压性损伤模型成功率高。

Objectives:To set up an experimental animal model of spinal nerve root chronic compression in-jury caused by self-bone hyperplasia,so as to provide a model-making method for relevant experiments.Method:30healthy cats with weight between3to5kilograms and sex at random.After having exposed the nerve roots of right side and the intervertebral foramina,transplanting autogenous cancellous bone to the nerve root pathway.Left side was for contral.MEP examinations were taken before the operation and at the2nd,4th,8th,12th and24th weeks after the operation.Every time6cats were chosen at random for neuropathology ex-amination and intervertebral foramina section area measurement.At the same time,4to5cats were examined by X-ray,CT and MRI to determine the narrowness of the nerve roots pathway and the situation of compres-sion.Result:Abnormal behavior of extremity on experimental side occurred in early post-operation,followed by muscular atrophy to different extent.In late post-operation,ulcer appeared at the distal limbs.With prolongation of the compression period,increased osteotylus occurred in the intervertebral foramina of the experimental side which became narrower,and nerve roots were deformed due to compression.The section area was reduced sig-nificantly8weeks later with significant difference from the contrast side.The main changes of the nerve root were the edema of perineurium?endoneurium and myelin swelling.myelin decorticated segmentally4weeks lat-er.Nerve axon became thicker and broken,peripheral Wallerian degeneration8weeks later.12weeks later,the degenerated never structure destroyed and absorbed,followed by the cavities formation.The whole nerve became fibrosis in24weeks.4weeks after operation,incubation period of MEP on experimental side started to pro-long,differentiation of wave shape was unclear at the8th week,amplitude dropped at the12th week,and24weeks later,there were difficulties in MEP induction and part potential disappeared.Conclusion:Making a mod-el of nerve root chronic injury by transplanting autogenous cancellous bone into the intervertebral foramina is simple and can be applied to any segment of spine,and its injury location and form is very close to the clin-ical.