兔外伤性视神经损伤后不同时期减压的视功能动态检测

Functional changes of the optic nerve following traumatic optic nerve injury in rabbits

目的:观察视神经损伤动物模型在损伤后不同时期视神经管减压后视觉诱发电位的变化,了解外伤性视神经损伤的手术时机与疗效间的关系。方法:建立家兔外伤性视神经损伤及不同时间减压的模型,随机分为A、B、C、D、E共五组,分别为正常对照组、损伤48 h减压组、1周减压组、2周减压组以及损伤不减压组。采用图形翻转视觉诱发电位(P-VEP)检测A组视功能,B、C、D组在损伤前、后1 h,减压前1 h、减压后2周以及E组相应时间的视功能变化。结果:①每只健康家兔P-VEP检查均引出典型NPN曲线,视神经挤压伤后1 h NPN波形低阔扁平,P波潜伏期延长,波幅降低,与自身损伤前及正常对照组相比有显著性差异(P<0.05)。②减压前后各组自身对照:B组减压前后的P波潜伏期和波幅有显著性差异(P<0.05);C组无显著性差异(P>0.05);D组波幅无显著性差异(P>0.05),而减压后2周潜伏期明显延长(P<0.05)。③减压后2周B、C、D组两两比较,三组之间潜伏期均差异有显著性意义(P<0.01),B组与C、D组波幅比较均有极显著差异(P<0.01),C、D组之间波幅有显著性差异(P<0.05)。B、C与E组之间潜伏期和波幅均有极显著性差异(P<0.01),而D、E组之间均无明显差异(P>0.05)。B组与A组的潜伏期和波幅无显著差异(P>0.05),C、D、E组与A组之间均有极显著差异(P<0.01)。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间接损伤,损伤后较早期(48 h以内)减压可阻止轴突继发性损伤,避免视功能进一步下降,并可在一定程度上逆转视功能的损害。

Objective ： To observe the changes of visual evoked potentials following traumatic optic nerve injury. Methods： Thirty rabbits were randomly divided into Group A （normal control）, B （48-hour decompression）, C （ 1-week decompression）, D （2-week decompression） and E （non-decompression） following traumatic optic nerve injury. The functional changes of the optic nerves at different times were observed by quantitative study of the pattern reversal visual evoked potentials （P-VEP）. Results： P-VEP of the healthy rabbits revealed typical NPN contours, while the NPN waves in the injured groups were low and flat. The latency period of P waves was lengthened and the amplitude reduced. Compari- sons of the amplitude and latency period of P waves in P-VEP before and after decompression showed statistical differences, significant in Group B and insignificant in Group C （ P 〈 0.05 ） ; the difference of the latency period was statistically significant while that of the amplitude insignificant in Group D. Comparisons of P-VEP at 2 weeks after decompression showed that the differences in the latent period were extremely significant between every two of Groups B, C and D （ P 〈 0.01 ） as well as in the amplitude be- tween Group B and C and D （ P 〈 0.01 ）, but significant between Group C and D （ P 〈 0.05 ）. The differences in the latency period and amplitude were extremely significant among Group B, C and E （ P 〈 0.01 ） but insignificant between Group D and E （P 〈 0. 05 ）. Conclusion： Optic nerve decompression helps protect the visual function in indirect optic nerve injuries.