Recording of spared motor evoked potentials and its augmentation by 4-aminopyridine in chronic spinal cord-injured rats  

脊髓损伤晚期大鼠细胞外记录运动诱发电位及4-氨基吡啶对其增强作用的研究(英文)

作　　者：余科炜[1] 李家顺[1] 戎伟芳[1] 贾连顺[1] 袁文[1] 叶晓健[1] 石志才[1] 戴伯军[1] 

机构地区：[1]上海市武警上海总队医院骨科,上海201103

出　　处：《Chinese Medical Journal》2001年第2期43-49,106-107,共9页中华医学杂志（英文版）

基　　金：thegrantsfromtheAdvanceDepartment FoundationfromtheMedicalMinistryofShanghai China! (No 1995 Ⅲ 0 0 8)

摘　　要：Objective　To research the direct electrophysiological evidence of discomplete spinal cord injury (SCI) and the effect of 4-aminopyridine on it.Methods　Motor evoked potentials (MEPs), both spinal cord recorded MEPs (scMEPs) and extracellularly recorded MEPs (exMEPs) were recorded and characterized on a T13 epidural electrode (scMEPs) and an extracellular microelectrode (exMEPs) for 10 normal rats and 40 rats with lesions of various severity (sham, 35?g*cm force (gcf), 70?gcf, 100?gcf impact injury) at the T8-T9 cord using the Allen's drop model. The incline plane and Tarlov techniques were used to assess clinical neurological function. Results　MEPs in the normal rats were elicited by applying transcortical suprathreshold stimulation consisting of 3-4 early negative peaks (N1, N2, N3 and N4) followed by several late waves. The N1 and N2 peaks were largest in the anterior and ventrolateral funiculus, respectively, which was indicative of extrapyramidal pathways. The 100?gcf impact injuries and the cord transection abolished the MEP distal to the lesion, whereas the 35?gcf injuries resulted in a latency shift and amplitude decrement of the MEP peaks. Eighteen of the 20 rats with 70?gcf injuries showed clinical paraplegia. Among them, 7 rats had neurophysiological evidence of residual conduction pathways through the lesioned cord segment, such as the presence of N1 and N2 peaks in the scMEPs or exMEPs. After 4-aminopyridine (4-AP) administrations (1?mg/kg), the amplitude of the spared exMEP increased significantly and spread more widely. Conclusions　MEPs evoked by transcortical stimulation travel mostly in the extrapyramidal tract. MEP monitoring could provide an excellent method of detecting the functional integrity of the motor tracts after SCI, and could even detect spared motor fibers after discomplete SCI. Furthermore, the use of 4-AP or other K+ channel blocking agents may be a potential treatment for patients with chronic moderate to severe SCI.目的　探索非完全性脊髓损伤 (discompleteSCI)的直接电生理证据以及 4 氨基吡啶 (4 AP)的影响。方法　采用Allen’s打击模型造成T8-T9脊髓不同程度损伤 (空白组 35gcf损伤组 70gcf损伤组 ,10 0gcf损伤组 ) ,分别测定 10只正常大鼠和 4 0只脊髓损伤大鼠的硬膜外运动诱发电位 (scMEP)和细胞外运动诱发电位 (exMEP) ,并采用斜板试验和Tarlov评分系统判断脊髓神经功能。结果　超阈值经皮层刺激下正常大鼠的运动诱发电位 (MEP)包括 3- 4个早期负向波峰 (N1,N2 ,N3,N4 ) ,以及后续不稳定的晚期成分。最大波幅的N1和N2 分布在脊髓前束和腹外侧束 ,即锥体外系传导途径。 10 0gcf损伤组及脊髓横断组损伤水平以下MEP信号消失 ,而 35gcf损伤组MEP波幅降低 ,潜伏期延迟。 70gcf损伤组的 2 0只大鼠中 ,18只按临床标准属全瘫 ,但神经生理学检查证实其中 7只大鼠的脊髓损伤节段仍有传导功能 ,例如scMEP或exMEP的N1和N2 波仍保留。给予 4 AP后 ,残存的MEP波幅显著增高 ,分布范围扩大。结论　经皮层刺激诱发的MEP主要经锥体外系传导。MEP监测可提供一种直接检测SCI后脊髓运动传导束功能状态的方法 ,甚至可发现非完全性SCI中部分残留的运动神经纤维。而使用 4 AP或其他K+通道阻滞剂可能是治疗中、重度SCI晚期病人潜在?

关 键 词：motor evoked potential  ·   microelectrode  ·   discomplete spinal cord injury  ·  4  aminopyridine  ·   rat 

分 类 号：R338.21[医药卫生—人体生理学]