引起脊髓亚急性压迫损害的椎管内容积改变的实验研究

Experimental study of dimensional c hanges of the spinal canal in subacut e compressive injuries of the spinal cord

目的通过测定脊髓亚急性压迫损伤时的椎管内容积的改变,研究脊髓耐受压迫变形的能力。方法通过使用自制的水囊加压器缓慢压迫脊髓,制成脊髓压迫动物实验模型,以皮层体感诱发电位(CSEP)的变化作为监测指标,研究脊髓受压与椎管容积改变的关系,评价脊髓功能的变化,观察组织病理学改变。结果(1)脊髓受到慢性压迫时,CSEP波幅逐渐下降,潜伏期逐渐延长,但波幅下降不超过50%,脊髓传导功能就能逐渐恢复,波幅及潜伏期也会逐渐恢复;(2)脊髓耐受亚急性压迫的椎管内容积改变的临界值:脊髓压迫率为0.49±0.09,Pavlov比值为0.52±0.12,椎管矢状径狭窄率为36.51%±8.82%,椎管侵占率为23.04%±2.36%;(3)Tarlov评分术后1周与对照组差异无显著性;(4)压迫部位脊髓除了变扁增宽外,未见到明显的病理改变,脊髓功能未见明显障碍。结论脊髓耐受压迫变形的能力很强,影像学显示的神经通道狭窄不能单纯作为诊断脊髓压迫症的依据,必须与临床症状相结合。

Objective To test the ability of the spinal cord to resist compression and adapt to th e deformation without marked functio nal impairment by measuring the chan ges of the spinal canal dimensions in subacute compressive injuries of th e spinal cord.Methods The model of subacute spinal cord com pression was produced by a small water sac plac ed in posterior extradural space of t he L 1 segment in cats.The extent of the cord compression was evaluated b y monitoring cortical somatosensory evoked potential(CSEP).When the amplitude of CSEP decreased about 50%,the water sac was ligated and assem bled in the back of spinal canal.CSEP and Tarlovs score were recorded later on in a daily and weekly basis.Then the cats were sacrificed for histo-pathological studies.The ch anges in dimensions of the spinal cords were also measured.Results1)As the compression was exerted,CSEP showed a slight delay in latency concurrent with the reduction of am-plitude.However,if decrease of the amplitude was less than 50%,the ampl itude and latency could partly recover after one week.2)The critical cord compression ratio was 0.49±0.09,Pavlovs ratio was 0.52±0.12,the spinal canal narrow ratio i n the sagittal plane was 36.51%±8.82%,the canal occupation rate was23.04%±2.36%.3)Tarlovs score was 3.21±0.58.There was no apparent difference compared with the control group after 1week of the inju ries.4)No significant pathological change s were observed in the white and gray matter under the light micro scopic examination in experimental groups.Conclusion The spinal cords have the ability to resist comp ression and adapt to the deformation without marked functional loss.The diagnosis of compressive myelopath y not only depends on radiological ap pearance but also on clinical neurologic signs.[