牵张性脊髓损伤脊髓SCEP监护作用的实验研究

目的：探讨脊髓皮层诱发电位对牵张性脊髓损伤的监护作用。方法：选用４０只健康大白兔，随机分成对照组（Ａ组）、体感皮层诱发电位（ＳＣＥＰ）波幅下降３０％组（Ｂ组）、ＳＣＥＰ波幅下降５０％５ｍｉｎ组（Ｃ组）和１０ｍｉｎ组（Ｄ组）。通过对脊髓ＳＣＥＰ监测、动物脊髓功能评定、组织形态学观察以及脊髓微血管铸型扫描电镜观察来研究牵张性脊髓损伤。结果：随着牵开负荷增大和作用时间的延长，脊髓微血管发生充盈缺损、痉挛直至破裂出血；Ｃ组及Ｄ组脊髓功能下降，与Ａ组相比有显著性差异。结论：ＳＣＥＰ波幅变化能较客观地反映脊髓功能状况，波幅下降５０％持续１０ｍｉｎ脊髓将出现不可逆损害     

缺血和再灌流对脊髓血流量及运动诱发电位的影响

本文采用家兔失血性休克模型，使血压下降至３０ｍｍＨｇ维持３０ｍｉｎ后再灌流，让血压回升到正常范围。观察缺血再灌流期 ＳＣＢＦ和 ＳＥＰ变化。缺血期平均动脉压 ３０～４０ｍｍＨｇ，脊髓 Ｔ１２及Ｌｌ节段灰质血流量减少５７％～６４％，白质血流量减少３２％～５０％；ＳＭＥＰ的潜伏期明显延长（Ｐ＜０．００１），各波的波幅降低并有２５％～６７％的波幅消失。再灌流期当血压回升到９０～１３０ｍｍＨｇ时，灰质血流量仍低于伤前（Ｐ＜０．０１），白质血流量无显著差异．ＳＭＥＰ潜伏期仍明显延长（Ｐ＜０．０５），除Ｐｌ波波幅下降有统计意义外，其它各波幅无差异，波幅消失占２５％～３３．３％。光镜下见脊髓存在损伤性病理变化，显示缺血再灌流后脊髓组织仍然存在继发缺血性病理损害和神经功能障碍。     

脊髓损伤皮层体感诱发电位（CSEP）术中监护的实验研究

目的：通过开展皮层体感诱发电位（ＣＳＥＰ）术中监护脊髓损伤的实验研究，以确定脊髓损伤的临界值并有效的评价预后，为临床应用提供依据。方法：２８只中国家犬随机分成４组，用ＡｌｅｎＷＤ法致脊髓轻度、重度和完全性损伤，术中ＣＳＥＰ动态监测，并观察伤后１～３个月脊髓组织学改变、ＣＳＥＰ和功能恢复情况。结果：脊髓损伤ＣＳＥＰ术中监护临界值为，伤后２分钟Ｐ１潜伏期较术前延长不超过１．５倍，波幅下降不超过５０％；伤后１０分钟Ｐ１潜伏期较术前延长不超过１．８倍，波幅下降不得超过５５％。波幅变化灵敏，其恢复早于形态学及功能变化。结论：ＣＳＥＰ术中监护脊髓损伤较准确可靠，并能评价其预后。     

大鼠牵张性脊髓损伤后胶质纤维酸性蛋白的表达及意义

目的分析大鼠牵张性脊髓损伤后星形胶质细胞中胶质纤维酸性蛋白(GFAP)表达的变化。方法大鼠脊髓T13～L2经牵张损伤,皮层体感诱发电位(CSEP)监测P1～N1波幅下降至术前波幅70%后,分别于术后1、4、7、14、21d处死取材。应用免疫组化染色及图像分析检测星形胶质细胞中GFAP的表达,用行为学评分及电生理检查大鼠神经功能情况。结果损伤组术后1dGFAP阳性表达开始增多,术后14d达高峰,为(263.72±16.39)个,以后下降。损伤组各时相点的阳性表达与空白对照组比较差异有显著性(P<0.01)。结论牵张性脊髓损伤后GFAP的大量表达对脊髓的再生修复起着重要作用。     

体感诱发电位在椎管内占位显微手术中的监测

目的 评价体感诱发电位(SEP)在神经外科脊髓疾病显微手术中的监测作用，避免或减少医源性脊髓损伤。方法 28例病人行术前、术中EP全程监测，包括脊髓EP(SSEP）及皮层SEP(SSEP)，术中及时把监测信息反馈给术者。并将术中监测结果与术后疗效对照分析。结果 椎管内占位手术在行髓内肿瘤切除时最易引发EP波幅降低及潜时延长。术中监测按Frankel分级D、E级患者波幅较基准电位下降不超过50％，潜伏期延长不超过7％；B、C级患者波幅较基准电位下降不超过40％；潜伏期延长不超过5％。术后不会引起脊髓功能不可逆损害。结论 脊髓手术时行EP和SSEP联合监测可及时反映出脊髓功能的变化，提高术者术中操作的安全性，避免或减少术后并发症。     

皮层体感诱发电位术中监护脊髓损伤的实验研究与临床应用

为开展皮层体感诱发电位(CSEP)术中监护脊髓损伤,确定脊髓损伤的临界值及有效的评价预后,采用30只中国家犬,造成不同程度的脊髓损伤,术中CSEP动态监测,并观察伤后1—3个月脊髓功能恢复情况。结果显示:脊髓损伤CSEP术中监护临界值为P_1潜伏期较术前延长不超过1.5倍。波幅下降〈50％;波幅变化灵敏,其恢复早于形态学及功能变化。临床应用35例,结果表明CSEP术中监护脊髓损伤准确、可靠。     

常压及控制性降压下脊髓急性牵拉损伤比较研究

目的 评价控制性降压是否增加脊髓对牵拉损伤的易感性。材料与方法健康成年杂种犬6只，随机分为常压和控制性降压脊髓牵拉损伤组。观察常压及控制性降压水平下相同程度牵拉损伤后脊髓血流(SCBF)、体感诱发电位(SEP)、神经源性运动诱发电位(NMEP)改变的差异。结果 外周血有创动脉压(MABP)平均下降幅度为40．5％。经SSPS统计软件独立样本t检验，不同牵拉水平下，常压组及低压组的SCBF(％)、SEP波幅(Asep)(％)及NMEP波幅(％)无显著差异。结论 尼卡地平控制性降压不增加脊髓对牵拉损伤的易感性。     

SCEP监测在脊柱外科手术中的应用

１９９０年３月～１９９２年１２月对５５例脊柱外科手术患者进行了脊髓诱发电位（ＳＣＥＰ）术中监测，无１例出现不可逆的神经损伤并发症。术前脊髓神经功能正常组２７例中有２例出现了电位波幅明显变化。２５例术前伴有不全截瘫，在脊髓减压后出现振幅增大、潜时加快的电位图象，术后患者神经功能障碍有了明显的改善。３例完全性截瘫者，术中脊髓诱发电位波幅消失，但在减压后有１例出现了电位波幅，术后截瘫得到了部分恢复。在硬膜外放置刺激及记录电极线记录ＳＣＥＰ的方法可得到大而稳定的电位波幅，能够准确地反应出脊髓功能的即时变化。     

兔牵张性脊髓损伤的病理形态学改变

为了探索牵张性脊髓损伤的病理机制。我们选用４０只健康日本大耳白兔，随机分成对照组、体感皮层诱发电位波幅下降３０％组，５０％５分钟组、５０％１０分钟组。通过对动物运动功能评价、脊髓组织内丙二醛（ｍａｌｏｎｙｌｏｄｉａｌｄｅｈｙｄｅ，ＭＤＡ）和过氧化物歧化酶（ｓｕｐｅｒｏｘｉｄｅｄｉｓｔｕｍａｓｅ，ＳＯＤ）定量分析、组织形态等方法，研究牵张性脊髓损伤。结果显示：随着撑开负荷增加和作用时间延长。导致脊髓灰白质内血管充盈不足、痉挛直至血管破裂出血。脊髓组织内ＳＯＤ含量下降、ＭＤＡ含量升高。５０％５分钟组和５０％１０分钟组的Ｔａｒｌｏｖ评分障碍率和Ｍｏｌｔ斜板障碍率增大。与对照组相比，其差异有显著性。研究证明脊髓血管的改变是牵张性脊髓损伤的早期病理机制，而自由基介导的脂质过氧化反应则参与了牵张性脊髓损伤的继发性损害过程。     

快速交换球囊扩张导管技术制备兔急性脊髓压迫损伤模型

目的 :探讨快速交换球囊扩张导管技术制备兔单纯脊髓压迫损伤模型的可行性。方法 :将24只新西兰大白兔随机分为3组,麻醉成功后备皮,以T10为中心取背部正中切口,长约4cm,显露T8~T11,假手术组(A组)行T8一侧椎板切除,不置入球囊;对照组(B组)将T8一侧椎板切除后置入球囊达T10水平,不扩张球囊;实验组(C组)行T8一侧椎板切除后,将球囊通过T8置入达T10水平,将球囊快速充起,占据椎管前后径约30%,术中采用CT平扫确定球囊位置并记录球囊扩张达到占位程度时的压强值并维持此压强值压迫48h。术前和术后48h行体感诱发电位(SSEP)检查并记录图形和数值变化,采用改良Tarlov评分记录各组术后48h动物后肢活动情况。同时记录各组兔术后1d、2d体重下降值和饮食量。术后2d各组随机选取5只实验兔取出以T10为中心脊髓组织进行病理学检查,每组剩余3只均以T8为中心上下约0.5cm范围进行拆线,B、C组将球囊内压力减为负压后将球囊轻轻抽出,最后缝合切口,继续观察并记录术后4d、7d、14d时体重下降值及饮食量。结果:C组造模球囊扩张达到椎管前后径30%占位程度时球囊内压强为67.23±22.34k Pa,95%置信区间为(48.55~85.91)k Pa。造模术后C组SSEP波幅显著性降低,与A、B组术后及C组术前比较均有统计学差异(P0.05),A组与B组比较差异无统计学意义(P0.05)。造模后48h改良Tarlov评分A组(6.00±0.00分)与B组(5.88±0.35分)比较差异无统计学意义(P0.05),A、B组与C组(1.13±0.35分)比较差异均有统计学意义(P0.05)。术后1d、2d、4d、7d、14d时3组兔体重下降值及饮食量均无统计学差异(P0.05),术后14d时体重恢复至正常体重,术后7d时饮食恢复正常。结论:快速交换球囊扩张导管技术制备兔单纯脊髓压迫损伤模型可模拟临床急性脊髓压迫损伤的状态。     

The influence of spine distraction on cat spinal cord blood flow and evoked potentials

The changes of spinal cord blood flow (SCBF) and spinal cord evoked potential (SCEP) due to spine distraction were analyzed in 30 cats. Spine distraction was performed at L1/2 level at which spinal bodies were separated surgically. SCBF was measured by means of a microsphere technique before, during and after spine distraction and SCEP elicited by spinal cord electrical stimulation was recorded simultaneously. With slight spine distraction (SCEP amplitude 80-100%), SCBF was increased significantly over normal value. SCBF was decreased significantly by further distraction (SCEP 50-80%), but was recovered over normal value after the release of distraction. When severe distraction (SCEP less than 50%) was applied, decreased SCBF around L1 level was irreversible. These results suggested that the disorder of SCBF regulating system due to spine distraction could be expected by analyzing changes of the SCEP.     

Transcranial motor-evoked potentials monitoring can detect spinal cord ischemia more rapidly than spinal cord-evoked potentials monitoring during aortic occlusion in rats

In this study, we evaluated the efficacy of transcranial motor-evoked potentials (tc-MEPs), compared with segmental spinal cord-evoked potentials (SCEPs), for detecting spinal cord ischemia (SCI) and assessed the relationship between neurological outcome and tc-MEPs or SCEPs in the rat aortic occlusion model. In the rats, SCI was induced by aortic occlusion for 10 min with a balloon catheter. At first, tc-MEPs (Group A: n = 6) or segmental SCEPs (Group B: n = 6) was recorded during SCI. Second, in using the quantal bioassay for the relationship between an interval of aortic occlusion and the probability of positive response in tc-MEPs or segmental SCEPs, the P50_MEP and P50_SCEP which represent the interval of aortic occlusion associated with 50% probability of assessment of ischemic spinal cord dysfunction by tc-MEP and SCEP were analyzed. The amplitude of tc-MEPs decreased significantly at 30 s and disappeared completely at 2 min after aortic occlusion. In Group B, it took about 6 min after aortic occlusion to diminish SCEP signal amplitude by approximately 50%. P50_MEP obtained in the quantal analysis was 0.3 ± 0.1 min. P50_SCEP was calculated as 6.2 ± 0.5 min that was significantly (P < 0.01) longer than P50_MEP. Our data indicated that tc-MEP monitoring could detect the onset of SCI so rapidly in comparison with segmental SCEP monitoring, which could provide therapeutic windows in a surgical approach that includes spinal cord protection.     

Evaluation of various evoked potential techniques for spinal cord monitoring during scoliosis surgery

STUDY DESIGN: This prospective study compared the outcomes of different evoked potential (EP) techniques for intraoperative spinal cord monitoring. OBJECTIVES: To evaluate the reliability of different EP techniques administered during scoliosis surgery. SUMMARY OF BACKGROUND DATA: A number of different methods of intraoperative spinal cord monitoring are available. Because each has its own advantages and limitations, multimodal spinal cord monitoring has been proposed to improve monitoring reliability. MATERIALS AND METHODS: Cortical somatosensory-evoked potential (CSEP), cortical motor-evoked potential (CMEP), spinal somatosensory-evoked potential (SSEP), and spinal cord-evoked potential (SCEP) were applied simultaneously to 30 patients undergoing surgical correction for spinal deformity. The presence of the EP waveforms and their reproducibilities over separate tests were compared. In addition, the monitoring outcomes were evaluated with the clinical results. RESULTS: Of the 30 patients, CSEP waveforms were successfully recorded in 28 cases (93%), SCEP in 25 cases (83%), CMEP in 24 cases (80%), and SSEP in 21 cases (70%). Latencies of each EP technique showed no significant variability. However, amplitudes showed significant differences between different techniques. SCEP and CMEP showed clearer waveforms of greater amplitude that could be detected faster than CSEP and SSEP waveforms. SCEP and SSEP waveforms were more easily influenced by the surgical procedure. CONCLUSION: CSEP and CMEP are recommended for routine monitoring, so that both ascending and descending tracts are monitored. If adequate signals for either of these proposed monitoring methods cannot be easily obtained, SSEP can substitute for CSEP, whereas SCEP can substitute for CMEP.     

甲基强的松龙预防牵张性脊髓损伤的实验研究

为探索甲基强的松龙（ＭＰ）对牵张性脊髓损伤的防治作用，选用日本大耳白兔４８只，随机分为对照组（Ａ、Ｂ）、实验组（Ｃ、Ｄ）。实验组于伤前３０分钟一次静脉缓慢推注ＭＰ３０ｍｇ／ｋｇ；伤后１５分钟开始，每１小时静脉滴注ＭＰ５．４ｍｇ／ｋｇ，持续５小时。对照组用生理盐水治疗。采用皮质体感诱发电位（ＳＣＥＰ）监护、组织形态学、脊髓组织生化测定、运动功能评定等方法评价。结果表明，Ｃ组、Ｄ组较Ａ组、Ｂ组ＳＣＥＰＰ１波波幅恢复快速、稳定；伤后８小时及１４天运动功能评定其障碍率低于Ａ组、Ｂ组（Ｐ＜０．０５）；脊髓前角灰质神经元体积密度及１００μｍ白质范围内有髓神经纤维数高于Ａ组、Ｂ组（Ｐ＜０．０５）；丙二醛含量低于Ａ组、Ｂ组，过氧化物歧化酶含量高于Ａ组、Ｂ组（Ｐ＜０．０５）；神经元及神经纤维变性、坏死，灰质出血范围及脊髓微血管痉挛程度明显轻于Ａ组、Ｂ组。认为，在脊柱畸形矫正术前应用大剂量ＭＰ，具有预防牵张性脊髓损伤的作用；伤后及时给予ＭＰ，可减轻脊髓继发性损伤     

Effect of stimulation parameters on intraoperative spinal cord evoked potential monitoring

The purpose of this study was to investigate the effects of the stimulus parameters on spinal cord evoked potential (SCEP) and to recommend a practical epidural stimulation protocol for intraoperative spinal cord monitoring. This prospective study compared the latencies and amplitudes of SCEP obtained on epidural stimulation of 30 patients with scoliosis under anesthesia using different stimulus pulse duration and stimulation rates. SCEP was found to be undetectable with shorter stimulus duration (<0.05 ms). The SCEP latencies did not show any significant difference among different stimulation parameters. However, the SCEP amplitude showed significant changes with differing stimulus durations. The SCEP amplitudes were found to significantly decrease when the pulse durations become shorter than 0.2 ms. Stimulus parameters showed significant effects on SCEP amplitude but not latency. Stimulus rates in the range of 21 to 61 Hz are equivalent for quick and reliable detection of SCEP. Considering the short latency of SCEP, a pulse duration of 0.2 ms is recommended for SCEP using epidural stimulation.     

The effect of direct lidocaine injection into the clamped aortic segment on the spinal evoked potential: early diagnosis for spinal cord ischemia.

PURPOSE: The aim of this study was to identify a method to determine whether segmental artery reconstruction was indicated during aortic clamping. METHOD: Spinal cord evoked potential (SCEP) and regional spinal blood flow were studied in 24 adult dogs. Using the left heart bypass technique, aortic clamping divided the aorta into thoracic, abdominal, and terminal segments. After the occlusion of the descending aorta and discontinuation of the perfusion to the abdominal segment, animals were assigned to four groups: no treatment with perfusion to the terminal aorta (group IA), no treatment with cessation of bypass (group IB), 5% lidocaine administration (5 mg/kg) into the abdominal segment with perfusion to the terminal aorta (group IIA), and lidocaine administration with cessation of bypass (group IIB). RESULTS: Cessation of bypass reduced spinal blood flow and SCEP amplitude. Lidocaine injection allowed for a significant rapid decrease in SCEP amplitude in group IIB compared with group IB (24.2% +/- 13.4% versus 92.3% +/- 33.2%; p = 0.0039). The degree of spinal blood supply was reflected immediately in the magnitude of SCEP amplitude change by the direct lidocaine injection. (group IB versus group IIB; p = 0.023). CONCLUSION: The direct injection of lidocaine into the clamped aorta results in a rapidly change in SCEP in the threat of ischemia and can be used to make an early detection of the segmental arteries perfusing to the spinal cord.     

山莨菪碱对牵张性脊髓损伤的防治作用

目的：探讨山莨菪碱（６５４２）对牵张性脊髓损伤的防治效果。方法：日本大耳白兔４８只,随机分为对照组、实验组。实验组于伤前１２、８、４ｈ各肌注６５４２１ｍｇ／ｋｇ;伤后１５ｍｉｎ开始每１ｈ静脉滴注６５４２０３ｍｇ／ｋｇ,持续５ｈ,此后每间隔４ｈ肌注６５４２１ｍｇ／ｋｇ到２ｄ。对照组用等量体积的生理盐水替代６５４２。采用脊髓功能监护、形态学、脊髓组织生化测定、运动功能评定等方法评定６５４２对牵张性脊髓损伤的防治作用。结果：实验组动物伤后８ｈ运动功能障碍率低于对照组,丙二醛（ＭＤＡ）含量低于对照组,过氧化物岐化酶（ＳＯＤ）含量高于对照组（Ｐ＜００５）;神经元及神经纤维变性、坏死,灰质出血范围轻于对照组。结论：伤前应用６５４２能保护脊髓微血管,抑制脊髓继发病理损害,促进脊髓功能恢复。