伽玛刀照射对猫视神经电生理学变化的影响

目的探讨不同剂量下伽玛射线照射后视神经电生理学的变化特点。方法20只猫随机分为5组,每组4只,1组作为对照,其余4组分别接受10Gy、11Gy、12Gy和13Gy伽玛刀的照射,分别于照射后3d、1周、半个月、1个月、2个月、3个月、4个月及5个月进行电生理监测。结果10Gy组电生理学没有变化,11Gy组在照射后1周出现了电生理学的变化,主要表现为潜伏期的延长,这种变化在半个月时有所恢复,随着时间的延长基本恢复正常。12Gy以上伽玛射线照射后出现了明显的电生理学异常变化,主要表现为潜伏期的延长和振幅的缩短,这种变化随着时间的延长而加重。结论引起视神经电生理学的变化特点与伽玛射线剂量有关,小剂量的伽玛射线可引起可逆性的变化,主要表现为潜伏期的延长。大剂量的伽玛射线可引起不可逆的视神经放射性损伤,这种损伤随着时间的延长逐渐加重,主要表现为潜伏期的延长和振幅的减小,随着时间的延长,振幅的减小更加明显。

Effect of Gamma Knife Irradiation on Electrophysiology of Optic Nerve in Cats

Objective To study the change in electrophysiological characteristics of the optic nerves caused by Gamma Knife irradiation in cats. Methods Twenty cats were randomly divided into 5 groups i.e. control group and 10 Gy, 11 Gy, 12 Gy and 13 Gy gamma knife irradiation groups. The changes in effectrophysiology of the optic nerves were determined in all the groups 3 days, 1 week, and 0.5, 1, 2, 3, 4 and 5 months after the irradiation respectively. Results There was no electrophysiological change in 10 Gy group. The latent period of visual evoked potential (VEP) was prolonged 1 week after 11 Gy irradiation, and gradually returned to normal from 0.5 to 2 months after 11 Gy irradiation. The increase in the latent period of VEP and decrease in the amplitude of VEP were observed 3 days after 12 Gy or more irradiation. The above-mentioned changes become more significant with the lapse of time. Conclusions The changes in the electrophysiology of the optic nerve is related to the gamma knife dose of irradiation. The irradiation with 11 Gy gamma knife produces reversible prolongation of the latent period of VEP, but the irradiation with 12 Gy or more can produce irreversible increase in the latent period and decrease in the amplitude of VEP, which mean the irreversible injury to the optic nerves.