Department of Neurosurgery, Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, China.
J Neurosurg. 2010 Jul;113(1):39-44. doi: 10.3171/2010.1.jns091116.
The authors' goal was to observe histopathological changes in the trigeminal nerve after Gamma Knife surgery (GKS) in rhesus monkeys, and to investigate the radiobiological mechanism of GKS for primary trigeminal neuralgia. The nerve length-dosage effect of irradiation is also discussed.
One of 5 rhesus monkeys randomly served as a control, and the other 4 monkeys were randomly administered a target radiation dose of 60, 70, 80, or 100 Gy (a different dose in each animal). The size of the collimator was 4 mm, and the target point was the trigeminal nerve root. In each experimental monkey, one side was exposed to single-target-point irradiation, and the contralateral side was exposed to double-target-point irradiation. After 6 months, the trigeminal nerve root was examined using light microscopy, transmission electron microscopy, and immunohistochemistry.
At each radiation dose, the damage to the nerve tissue by single-target-point irradiation was identical to that caused by double-target-point irradiation. In the trigeminal nerve tissues of the monkeys irradiated with 60 and 70 Gy, there was limited nerve demyelination and degeneration, fragmentation, or loss of axons. In the trigeminal nerve tissue of the monkey irradiated with 80 Gy, the nerve tissue showed a disordered structure. In the trigeminal nerve tissue of the monkey irradiated with 100 Gy, there was severe derangement in the structure of the nerve tissue, and extensive demyelination, fragmentation, and loss of axons.
The target doses of 60 and 70 Gy have very little impact on the structure of the trigeminal nerve. 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-point with the double-target-point irradiation, the extent of damage to the nerve tissue is identical, and no difference in the nerve length-dosage effect was found.
观察伽玛刀（GKS）治疗原发性三叉神经痛后三叉神经的组织病理学变化，探讨 GKS 的放射生物学机制。同时还探讨了照射神经长度剂量效应。
5 只恒河猴随机分为实验组和对照组，每组 4 只，实验组 4 只猴分别给予 60、70、80、100Gy （不同动物给予不同剂量）的靶剂量照射，准直器大小为 4mm，靶点为三叉神经根。每只实验猴一侧行单靶点照射，对侧行双靶点照射。照射后 6 个月用光镜、透射电镜、免疫组织化学观察三叉神经根。
在各剂量照射时，单靶点与双靶点照射的神经组织损伤相同。60、70Gy 组的神经组织仅有轻度脱髓鞘和轴突变性、断裂或丢失；80Gy 组的神经组织结构紊乱；100Gy 组的神经组织结构严重紊乱，广泛脱髓鞘、轴突变性、断裂和丢失。
60、70Gy 的靶剂量对三叉神经结构影响很小，80Gy 照射可引起部分轴突变性和脱髓鞘，100Gy 可引起部分神经元坏死。单靶点与双靶点照射时神经组织损伤程度相同，未发现神经长度剂量效应差异。
