兔外伤性视神经损伤后不同时期减压的形态学观察

目的观察视神经损伤模型在损伤后不同时期减压的形态学改变,了解其与手术时机的关系。方法建立家兔外伤性视神经损伤模型,将损伤分为正常对照组、损伤48h减压组、7d减压组、14d减压组及损伤不减压组,在光镜下观察各组视神经的组织形态学改变。结果正常对照组视神经纵切面胶质细胞基本呈柱形均匀排列,神经纤维排列整齐。损伤48h减压组纵切面胶质细胞排列基本均匀,损伤处可见空泡样变性,可见少量胶质细胞增生。损伤7d减压组纵切面胶质细胞排列紊乱,大部分区域出现多个大小不等的空泡,部分区域出现脱髓鞘样变,胶质细胞增生明显。损伤14d减压组纵切面胶质细胞完全丧失柱形排列,胶质细胞明显增生,视神经脱髓鞘样变明显。损伤不减压组可见大片神经纤维坏死,视神经脱髓鞘样变明显,胶质细胞增生。结论神经元继发性损伤是视功能进行性下降的重要原因,视神经减压术有利于减轻视神经的间接损伤,较早期进行减压(48h)可阻止轴突继发性损伤。

Morphological changes of optic nerve decompressed at different time periods following the traumatic optic nerve injuries in rabbits

Objective To observe the relations of morphological changes duo to decompression at different time periods to surgical timing for traumatic optic nerve injuries. Methods Animal models of traumatic optic nerve injuries were established. The animal models were divided into 5 groups: control group, non-decompression group and decompression groups (48 h, 7 d, 14 d after injury). At the same time, the morphological changes of optic nerve were observed under light microscope. Results In the control group, the optic nerve astrocytes presented as cylinder type and arranged regularly on the vertical section, and the neural fibers arranged neatly. In 48 h decompression group, the arrangement of astrocytes was basically regular on vertical section, and vacuoles and slight astrocyte hyperplasia were observed in the damaged area. In 7 d group, the arrangement of astrocytes was irregular on vertical section. A lot of vacuoles with various sizes, demyelination of the nerve, uncovered axons, and astrocyte hyperplasia were observed in most areas. In 14 d group, the cylindric arrangement of astrocytes disappeared completely and obviously. The astrocyte hyperplasia in the full vision field and obvious nerve demyelination were noted. In non-decompression group, necrosis in flakes, obvious nerve demyelination and astrocyte hyperplasia were found. Conclusion It is confirmed that the excessive loss of neurons due to secondary degeneration following optic nerve injuries is the most important factor for visual impairment. The optic nerve decompression is benefit to protection of visual function in indirect optic nerve injuries. Visual function is better improved by decompression in 48 hours.