Abstract:Objective To develop a new animal model of chronic cervical compressive myelopathy and to assess its feasibility.Methods Twelve Chong-ming goats were divided into two groups:control group(n=3)and experimental group(n=9).A new spinal cord compression device was placed into the C3 vertebral body by anterior approach operation,and the syringe valve was fixed subcutaneously.In the experimental group 0.1 ml of contrast agent were injected into the balloon every week after operation,which gradually expanded the balloon,resulting in the continuous compression to the experimental animal spinal cord.In the control group,after the implanation of compression device,we only punctured with the needle but did not inject the contrast agent each week.In the 4th week,8th week and 12th week,the Tarlov scoring method was used to grade the spinal motor function of the experimental animals,and the cervical vertebral X-ray and CT examination were performed,and 2 experimental animals were euthanized at different time points for pathological examination of the compression spinal section.Results The Tarlov scores were 5(normal)at all time points in the control group.Tarlov scores were not changed in the experimental group in the 4th week(n=9).In the 8th week(n=7)the Tarlov score was 4 in 3 goats and 5 in 4 goats.In the 12th week(n=5),the Tarlov score was 3 in 3 goats,2 in 2 goats.Imaging showed no obvious abnormalities in the spinal cord.The balloon compression system of the experimental group was stable,and the spinal cord was gradually compressed with the enlargement of the balloon after the continuous injection of the contrast agent.There was no obvious abnormality in the pathological examination.No obvious abnormalities were observed in the experimental group at the 4th week.In the 8th week,we found the spinal cord ventral horn neurons degeneration,decreased cell body size,but not seen obvious decrease of neuron number.Some white matter appeared mild demyelination changes.Some axises showed cavitation degeneration.In the 12th week,the neuronal cell degeneration was obvious.Necrosis,degeneration of nucleus,the diffuse demyelination of white matter,and the obvious degeneration of axonal vacuolar were found.Conclusion Modeling experimental animal postoperative spinal movement function,imaging and pathological examination results in chronic compression characteristic of cervical myelopathy show that the new type of spinal cord compression system can establish a stable and repeatable chronic animal model of spinal cord compression.
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