慢性脊髓损伤胶质瘢痕边界定位的实验研究

Precise localization of glial scar boundary in chronic spinal cord injury in dogs

目的探讨如何精确地定位慢性脊髓损伤胶质瘢痕边界，以期能得到在切陈瘢痕时对其边界切实可行的定位方法，为进行神经干细胞移植治疗慢性脊髓损伤提供基础理论支持。方法首先．用胸段脊髓半截断的方法制作犬慢性脊髓损伤模型，以骨窗上端第1个椎板下缘的后正中点为立体空间的坐标“原点”，测量半截断损伤的脊髓节段上端及下端到原点的距离。其次，模型犬饲养12周，应用MRI扫描脊髓正中矢状位，分别测量MRI矢状位上异常信号的上、下界到原点的距离；然后应用B超对脊髓进行检测，检查脊髓上超声信号变化情况。再次，对脊髓标本进行纵向切片并染色．显微镜下观察切片上胶质纤维染色结果并测量其长度。最后，比较MRj矢状位脊髓异常信号长度与病理切片上瘢痕长度的差异。结果MRI上异常信号的范围[（14．7±0．94）mm]大于手术损伤范围（10mm），其均值差值约为4．7mm。B超检测能分辨脊髓上的异常信号变化，而且信号变化明显、边界清晰，达到肉眼分辨水平。病理切片上测量到的胶质瘢痕范围[（18．6±1．19）mm]大于MRJ上测量得出的异常信号范围，其均值差值约为3．9mm。结论通过MRJ矢状位扫描，同时引入立体定向原理可基本上定位胶质瘢痕边界；病理学测量结果对影像学定位具有进一步纠正的应用价值；B超可帮助检测瘢痕是否有残留，进一步保证完全切除瘢痕。

Objective To establish a method for precise localization of the boundaries of the glial sears in chronic spinal cord injury for their complete resection to provide the experimental basis for neural stem cell transplantation studies. Methods Chronic spinal cord injury was induced in beagle dogs via partial transections of the thoracic segment of the spinal cord. Three months after the operation,with the posterior-medial midpoint of the inferior edge of the first vertebral plate above the bony window defined as the point-of-origin of a 3-dimensional space, the distances from the superior and inferior margins of the injured spinal segment to the point-of-origin were measured on anteroposterior magnetic resonance images （MRI）. B-mode ultrasound was used to detect the signal variations in the spinal cord. Immunohistochemistry was performed on the longitudinal sections of the spinal cord for microscopic measurement of the glial fiber lengths in comparison with the length determined by MRI. Results MRI defined a greater length （14.7±0.94 mm） of glial scars with abnormal signals than the actually injured length （10 mm）. Ultrasound detected obvious signal changes in the injured spinal cord with distinct boundaries of the injuries. The glial scar length in the spinal cord defined pathologically （18.6± 1.19 mm） exceeded that defined by anteroposterior MRI scanning. Conclusions Anteroposterior MRI scanning combined with stereotactic localization allows approximate determination of the glial scar boundary in the injured spinal cord, and the discrepancies can be adjusted according to the result of pathological measurements. Ultrasonic inspection helps detect the residue scar tissues after surgical resection to ensure complete glial scar resection.