伽玛刀照射猴三叉神经的病理组织学研究

目的 观察伽玛刀照射猴三叉神经的病理组织学变化,探讨伽玛刀治疗原发性三叉神经痛(TN)的放射生物学效应机制和照射神经长度-剂量的效应关系.方法 选择5只恒河猴,1只为对照,4只行伽玛刀照射,选择靶点为三叉神经根,一侧为单靶点照射,对侧为双靶点照射,给予剂量分别为60 Gy、70 Gy、80 Gy、100 Gy.照射后6个月取病理,行光镜、透射电镜及免疫组织化学检查.结果 在相同剂量照射下,单靶点照射与双靶点照射的神经组织结构损伤程度变化基本一致.60 Gy、70 Gy见少许神经纤维脱髓鞘,轴突变性、断裂或消失.80 Gy神经组织结构损伤程度加重.100 Gy神经组织结构损伤程度更重,可见部分神经坏死.结论 60 Gy、70 Gy对三叉神经的组织结构变化影响小,80 Gy可引起三叉神经部分轴突的变性、消失及脱髓鞘,更高的剂量(100 Gy)可导致部分神经坏死.单靶点照射与双靶点照射神经组织结构损伤程度相近,两者的照射神经长度-剂量效应关系差异无统计学意义.

Gamma knife irradiation - induced histopathological changes in the trigeminal nerves of Rhesus monkeys

Objective The authors sought to observe histopathological changes in the trigeminal nerve(TN)after Gamma knife treatment in rhesus monkeys and to investigate the radiobiological mechanism of Gamma knife treatment for primary trigeminal neuralgia. The nerve length dose effect of irradiation was discussed. Method One of five rhesus monkeys randomly served as control and the other four monkeys were randomly administered a target dose of 60,70,80, and 100 Gy respectively. The size of the collimator was 4 mm and the target point was the TN root. In each experimental monkey, one side was exposed to single - target point irradiation and the contralateral side to two - target point irradiation. After 6 months, the TN root was examined by light microscopy, transmission electron microscopy, and immunohistochemistry.Results At the same dose of radiation, the damage to the nervous tissue by single - target point irradiation was identical to that caused by two - target point irradiation. In the trigeminal nerve tissues of the monkeys irradiated with 60 and 70 Gy,there was scant nerve demyelination and degeneration, fragmentation, or loss of axons. In the trigeminal nerve tissue of the monkey irradiated with 80 Gy, the nervous tissue showed a disordered structure. In the trigeminal nerve tissue of the monkey irradiated with 100 Gy, there were severe derangement in the structure of the nervous tissue and extensive demyelination, fragmentation, and loss of axons. Conclusions The target doses of 60 and 70 Gy have very little impact on the structure of the TN. Irradiation at 80 Gy can cause partial degeneration and loss of axons and demyelination. A 100 Gy dose can cause some necrosis of neurons. Comparing the single - target irradiation with the two - target point irradiation,the extent of damage to the nervous tissue is identical and no difference in the nerve length dose effect was found.