高位视路损伤与管内段间接视神经损伤的比较

目的 探讨高位视路损伤的法医学鉴定问题。方法 搜集11例头部外伤致高位视路损伤的案例资料,与随机选取的20例管内段间接视神经损伤的案例资料进行比较,并就相关临床检查所见、电视野及闪光VEP特征进行分析。结果 与视神经损伤相比,高位视路损伤的临床常规检查,除视功能障碍的主诉外瞳孔对光反射及眼底均无阳性所见;电视野检查表现为双眼同向性偏盲,管内段视神经损伤表现为单眼视野缺损。在11例高位视路损伤者中,8例为枕叶皮层损伤,闪光VEP表现为双眼P1波潜伏期轻度延长,波幅基本正常;3例为皮层下损伤,表现为P1波潜伏期明显延长,波幅明显降低。视神经损伤闪光VEP表现为伤眼PI波潜伏期明显延长,波幅明显降低,甚至无波诱出。结论双眼视野同向性偏盲是高位视路损伤的特征性改变,高位视路损伤闪光VEP的异常率较低,但一旦双眼闪光VEP异常可以支持高位视路损伤的诊断,鉴定时应同时结合头颅CT及脑电图结果综合分析,加以确认高位视路损伤的存在。

Comparative study on the characteristics of the high site visual field injuries and the visual nerve injuriesafter the head trauma

Objective To Study the characteristics of the high site visual field injury and the LED-VEP after the head trauma for the purpose of the medico-legal appraisals. Methods 11 cases with cortical blindness resulted from the head injury were studied and then compared with 20 cases suffered from optical nerve injuries with respect to the clinical manifestations and characteristics of the visual field injury and LED-VEP. Results As compared with the characteristics of the optical nerve injuries, besides the subjective complain of lowering the visual field, there were not any positive findings in pupil reflex of light and retina examination in case of the high site visual field injuries. The electrical visual field test revealed the homony-mous hemianopia while the internal segment optical nerve injury manifested unilateral visual field defect. 8 out of 11 cases with cortical blindness, occipital cortex were injured and the flash VEP demonstrated the slight prolongation of the latent period of the PI wave of both eyes, while the PI amplitudes were normal. 3 out of 11 cases were suffered from the subcortical injuries and were manifested with the prolongation of the latent period of the PI wave and the amplitude of the PI wave were significantly reduced. Conclusion Bilateral homonymous hemianopia were the characteristics of the high site visual field injury while the abnormal rate of the flash VEP of the high site visual field was quite low. So that, homonymous hemianopia may be helpful for the diagnosis of cortical blindness. At the same time CT scanning and the electroen-cephalography (EEG) also must be considered comprehensively in the medico-legal appraisals.