经颅磁刺激运动诱发电位监测脊髓创伤的实验研究

目的：观察脊髓创伤与运动诱发电位的关系，了解运动诱发电位在脊髓中的传导通路。方法：对３９只猫采用脊髓Ａｌｅｎ损伤模型和部分切断伤模型进行经颅磁刺激运动诱发电位（ＴＭＳ－ＭＥＰ）监测。结果：脊髓轻度打击伤时，ＭＥＰ潜伏期即有明显延长，但恢复良好；中度打击伤时，ＭＥＰ潜伏期延长更明显，且不能完全恢复；重度打击伤时，大部分动物ＭＥＰ不能引出，至２４ｈ不能恢复。ＭＥＰ的改变与后肢功能变化及镜下脊髓病理改变一致。ＴＭＳ－ＭＥＰ对脊髓前索和外侧索的损伤敏感，并可间接反应脊髓柱后索损伤。结论：ＴＭＳ－ＭＥＰ经脊髓前索和外侧索传导，可敏感而准确地反映脊髓损伤后功能改变，是一种有效的监测脊髓功能的手段     

TMS—MEP监测脊髓缺血性损伤的实验研究

为观察经颅磁刺激的不同刺激量和脊髓缺血性损伤对运动诱发电位的影响，采用兔脊髓可逆性缺血损伤模型进行磁刺激运动诱发电位（ＴＭＳ－ＭＥＰ）监测。发现在４０％～８０％的刺激量时，ＭＥＰ相对稳定。脊髓缺血损伤后ＭＥＰ潜伏期延长或消失，恢复血供后ＭＥＰ先于后肢运动功能恢复，至４～６小时完全恢复正常，当脊髓缺血后２４小时出现继发性损伤时，ＭＥＰ再次出现异常，ＭＥＰ的表现和后肢运动功能变化及病理改变相一致。证实ＴＭＳ－ＭＥＰ可敏感而准确的反映脊髓缺血后改变，可用于监测脊髓的缺血性损伤。     

皮层体感诱发电位在评价脊柱脊髓损伤中的意义

作者对７０例脊柱脊髓损伤患者进行了９４次皮层体感诱发电位（ＣＳＥＰ）检查，根据ＣＳＥＰ各波的潜伏期、波幅及波形变化将结果分为四类，与Ｆｒａｎｋｅｌ分级有良好的相关性，并对脊髓有无损伤及损伤口试作出精确判断，客观定量评价了脊髓功能。此外，作者提出ＣＳＥＰ检查对治疗方案的制定有重要参考价值。     

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     

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。     

大鼠胚胎脊髓移植物对成体损伤脊髓运动功能修复的影响

为了探讨胚胎脊髓移植物对成体损伤脊髓运动功能修复的效应，取妊娠１４天胚胎大鼠脊髓组织，移植到成年大鼠脊髓半切洞损伤模型，术后进行联合行为记分（ＣＢＳ）和运动诱发电位（ＭＥＰ）检查。结果发现，移植组ＣＢＳ与对照组比较相差显著（Ｐ＜０．０５），移植术后４周以内两者相差非常显著（Ｐ＜０．０１）。移植组ＭＥＰ早期反应（Ｐ１，Ｎ１）的峰潜伏时恢复优于对照组（Ｐ＜０．０５）。结果提示，胚胎脊髓移植对成年宿主损伤脊髓的功能修复具有促进作用。这可能与胚胎脊髓组织能分泌多种神经营养因子、神经生长因子、神经递质，或激素的调节作用有关。     

脊髓急,慢性损伤CSEP的变化：（附127例报告）

１９８０年～１９９２年９月对１２７例急、慢性脊髓损伤行皮层体感诱发电位（ＣＳＥＰ）检查。急性脊髓损伤７７例，全瘫３９例，不全瘫３８例，伤后２周内做减压复位及内固定。术后１～１２个月作ＣＳＥＰ检查与术前对比，３９例全瘫中的２６例ＣＳＥＰ完全消失，瘫痪也无恢复；１３例术前有严重异常的ＣＳＥＰ，７例ＣＳＥＰ及部分皮肤感觉有恢复，余６例无变化。３８例不全瘫，术前有异常的ＣＳＥＰ，术后瘫痪及ＣＳＥＰ都有不同程度恢复。慢性脊髓损伤５０例，术前ＣＳＥＰ均有异常改变，治疗后除２例颈椎病的症状及ＣＳＥＰ无变化外，其余病例都有不同程度的恢复。作者还分析了在急、慢性脊髓损伤者检测ＣＳＥＰ中一些不可靠的原因及影响因素。     

300例截瘫的体感诱发电位检查

对唐山市１９７６年地震所致的截瘫伤员，随机抽样做体感诱发电位（ＳＥＰ）检查３００例，其中完全截瘫２０９例，不全截瘫９１例，共检查腓总神经和正中神经ＳＥＰ ６００侧，发现４１６侧完全性截瘫的ＳＥＰ全部消失，不全截瘫的１６６侧，５８％的ＳＥＰ存在。研究结果表明：不全截瘫病人ＳＥＰ消失与否与脊髓损伤平面以下的肌力状况无关，而深感觉则与ＳＥＰ的存在与消失显著相关。ＳＥＰ与足趾定位觉检查呈等级相关。ＳＥＰ不能直接反映急性脊髓损伤后运动功能是否良好，仅间接与脊髓的前索状况有关。本组根据９１幅异常ＳＥＰ图形，将其归纳为６种主要表现，并试图分析其发生基础及与临床的关系。急性脊髓损伤后ＳＥＰ消失多数预后不良，但在创伤初期确定其不恢复的最终时间仍有困难。     

脊髓损伤细胞内Ca^2＋变化及其与脊髓神经功能损害的关系

目的：观察脊髓损伤（ＳＣＩ）后细胞内Ｃａ２＋（［Ｃａ２＋］ｉ）的动态变化，探讨其与脊髓神经功能损害的关系。方法：Ａｌｅｎ＇ｓ法致伤大鼠脊髓，于伤后１、４、８、２４、７２和１６８小时，采用原子吸收光谱分析和Ｌａ３＋阻断技术测定伤段脊髓［Ｃａ２＋］ｉ含量，参照Ｋｏｎｒａｄ的方法记录脊髓运动诱发电位（ＭＥＰ），应用斜板试验评价大鼠的运动功能。结果：ＳＣＩ后伤段脊髓［Ｃａ２＋］ｉ显著升高（Ｐ值＜０．０５或０．０１），与脊髓ＭＥＰ的变化和大鼠运动功能的损害呈显著相关关系。结论：ＳＣＩ后，伤段脊髓［Ｃａ２＋］ｉ超载可能在ＳＣＩ的病理发展机制中有重要意义。     

TMS—MEP与CSEP诊断脊髓损伤的作用比较

目的比较脊髓损伤后经颅磁刺激运动诱发电位和皮层体感诱发电位检测的诊断价值。方法 １５只家猫脊髓部分切断和６９例ＳＣＩ的ＭＥＰ和ＣＳＥＰ检测。结果 ＭＥＰ对脊髓前柱损伤，前后柱混合损伤和肌力异常极敏感，对后柱损伤不敏感；而ＣＳＥＰ对脊髓后柱损伤，前后柱混合损伤和关节位置觉异常十分敏感，对前柱伤却相反。     

Experimental study of spinal cord evoked potentials in cats

Assessment of function of the spinal cord utilizing spinal cord evoked potentials (SEP) has become a useful diagnostic tool. In the present study, various aspects of characteristics of SEP were analyzed. The basic waveform of conductive SEP consisted of two major components, namely, N1 and N2, whose conduction velocities along the dorsal surface of the cord were 74 m/s and 55 m/s, respectively. Halothane inhalation caused reduction of N2 amplitude, whereas asphyxia caused latency delay of N2. Significant amplitude reduction of N1, N2 (p less than 0.005) and considerable latency delay of N1 were noted in ventral epidural recording. Although there was no relationship between severity of injury and the appearance of positive potentials, N2 tended to be positive-going in heavy injury. Findings of positive potentials showed that N1 originated in the area of ventral gray matter through the ventro-lateral column and N2 through the dorsal column.     

Somatosensory evoked potentials in the evaluation and follow-up of patients with cervical vertebral and spinal cord injuries

Somatosensory evoked potentials have been serially recorded in 21 patients with cervical spinal cord injury. Each patient received the SEP test and a full neurological examination within 1 day after admission, after surgery, and 3-6 weeks following admission. Further SEP test and clinical evaluation were carried out 3-6 months after injury. Neurological status was graded according to the Sunnybrook Scale. In all patients we evaluated latency and amplitude of SEPs obtained from both median and tibial nerve stimulation. Immediately following injury SEPs were absent in 6 patients, abnormal in 10, and normal in 5 patients. No surgery was carried out in patients with normal SEPs where myelography and CT scan could not demonstrate surgical lesions. Four patients had some distal motor improvement but SEPs still absent, one had traceable SEPs following surgery but no motor improvement. Surgery was performed in all 10 patients with abnormal SEPs: 7 patients improved following surgery. In two patients SEPs showed an early postoperative recovery with subsequent late clinical improvement. The SEP technique is well suited to the non invasive study of spinal cord condition and serial recording in patients with spinal cord injury. Although SEPs are of limited clinical value when absent immediately following trauma, the presence of well preserved median and tibial SEP in the postinjury period indicates the best prognosis for motor and sensory functions.     

体感诱发电位评价家兔脊髓冲击伤模型的神经机能变化

目的 探讨脊髓冲击伤前后的体感诱发电位的变化,评价家兔神经机能的改变程度.方法 应用改良霍普金森杠杆设备根据冲击波的压力不同(0.40 MPa,0.60 MPa,0.80 MPa)建立不同损伤程度的胸T9-T10脊髓冲击伤模型,12 h后用体感诱发电位仪分别计测家兔脊髓冲击伤前后的体感诱发电位,利用分析软件对诱发电位P...     

Intra-operative recording of cortical somatosensory evoked potentials as a method of spinal cord monitoring during spinal surgery

The experience with cortical somatosensory evoked potential (SEP) recording during 13 cases of spinal neurological surgery is described. Good quality cortical SEPs were obtained in eight patients with a variety of intradural and extradural spinal disorders. The short latency components of these waveforms were stable during anaesthesia with nitrous oxide, 0.5% halothane and fentanyl. Fluctuations in signal amplitude were, however, common. In the one patient in whom the cortical SEP waveform was distorted intra-operatively, there was an increased neurological deficit. In one normal and four patients with impairment of dorsal column function, no intra-operative cortical SEP was recorded. In these five patients spinal SEPs were recorded rostral to the level of spinal disease. Monitoring spinal cord function using cortical SEPs can provide useful neurophysiological information, however, there are limitations to its utility. These relate to difficulties in signal acquisition, the low signal amplitude, attenuation of the signal during intramedullary surgery and uncertainties in signal interpretation. All these problems are exacerbated if the patient has a pre-operative clinical somatosensory deficit. Although most of these problems can be overcome using spinal SEP monitoring, intra-operative SEP recordings are not an infallible guide to spinal cord integrity since they reflect the functional status of only the dorsal column-medial lemniscus pathway.     

Motor evoked potential in cats with acute spinal cord injury

We have previously reported that a motor evoked potential (MEP) can be produced by transcranial stimulation of the motor cortex in cats and humans. This signal travels in both dorsolateral and ventral spinal cord. We report here the evaluation of this evoked potential in comparison to the somatosensory evoked potential (SEP) in an acute spinal cord weight drop model. In all animals, the peripheral nerve signal was the component of the MEP most sensitive to injury. Often, it was significantly reduced in amplitude by incidental manipulation of the spinal cord during a careful laminectomy and then returned. It was lost first in animals with weight drop spinal cord injury and was abolished with as little as 50 to 75 g/cm of force. The spinal cord signal of the MEP was consistently more sensitive to injury than the SEP and was abolished at about 100 to 150 g/cm of impact. The cortical SEP was abolished at about 200 to 250 g/cm, and the spinal cord SEP was abolished at similar levels. The SEP returned earlier after injury than the MEP. Anesthetic agents had an effect on the MEP in the spinal cord and substantially changed the peripheral nerve signal, in both wave form shape and optimal stimulation frequency. Marginal cord injury and abnormal metabolic conditions caused the peripheral nerve signal to decrement in amplitude with increasing trial numbers during a run and become unstable. These latter effects need further characterization and are critical guides to investigative and clinical use of this test. This study indicates that the MEP is more sensitive than the SEP in detecting spinal cord injury.     

脊髓损伤后早期减压对诱发电位影响的实验研究

[目的]观察脊髓损伤后早期减压对体感诱发电位及经颅磁刺激运动诱发电位的影响，以探讨诱发电位在判断手术时机及预后中的应用价值。[方法]日本大耳兔32只随机分4组。A组为对照组，不造成脊髓损伤。B、C、D组为脊髓损伤组。对每组动物于不同时间分别检测SEP、MEP。分析波形的潜伏期、峰问波幅。用后肢的Tarlov分级法作伤后运动功能评分。取脊髓标本，行组织学观察。[结果]随着脊髓压迫时间的延长，SEP、MEP的潜伏期逐渐延长，波幅逐渐减小．波幅变化较潜伏期更为敏感。在恢复过程中，脊髓受压时间越短，诱发电位恢复越早。潜伏期恢复早于波幅，而且SEP恢复早于MEP，MEP的恢复早于功能评分。[结论]SEP与TMS-MEP对脊髓损伤十分敏感，能较早反映脊髓损伤程度，可用于指导临床手术治疗和判断预后。     

Long-term assessment of hind limb motor function and neuronal injury following spinal cord ischemia in rats

Recent evidence suggests that brain injury caused by ischemia is a dynamic process characterized by ongoing neuronal loss for at least 14 days after ischemia. However, long-term outcome following spinal cord ischemia has not been extensively examined. Therefore, we investigated the changes of hind limb motor function and neuronal injury during a 14-day recovery period after spinal cord ischemia. Male Sprague-Dawley rats received spinal cord ischemia (n = 64) or sham operation (n = 21). Spinal cord ischemia was induced by inflation of a 2F Fogarty catheter placed into the thoracic aorta for 6, 8, or 10 minutes. The rats were killed 2, 7, or 14 days after reperfusion. Hind limb motor function was assessed with the 21-point Basso, Beattie, and Bresnahan (BBB) scale during the recovery period. The number of normal and necrotic neurons was counted in spinal cord sections stained with hematoxylin/eosin. Longer duration of spinal cord ischemia produced severer hind limb motor dysfunction at each time point. However, BBB scores gradually improved during the 14-day recovery period. Neurologic deterioration was not observed between 7 and 14 days after reperfusion. The number of necrotic neurons peaked 2 days after reperfusion and then decreased. A small number of necrotic neurons were still observed 7 and 14 days after reperfusion in some of the animals. These results indicate that, although hind limb motor function may gradually recover, neuronal loss can be ongoing for 14 days after spinal cord ischemia.     

"Backfiring" in spinal cord monitoring. High thoracic spinal cord stimulation evokes sciatic response by antidromic sensory pathway conduction, not motor tract conduction.

Spinal cord stimulation has been advocated as an alternative to motor cortex stimulation for motor tract activation. To test this theory, evoked responses were recorded from lumbar spinal cord (L2; n = 14), spinal roots (L4-L7; n = 112), peripheral nerves (sciatics; n = 28), and hind limb muscles (n = 28) after epidural stimulation of the T1-T2 segment of the spinal cord in dogs (n = 12), cats (n = 2), and monkeys (n = 2). The spinal response evoked by spinal cord stimulation was resistant to a dorsal hemisectioning (depth, 7-8 mm) of the midthoracic spinal cord. A minimal attenuation of latency and amplitude occurred with dorsal hemisectioning, suggesting signal transmission through descending or ascending pathways in the ventrolateral and ventral quadrants of the spinal cord. The sciatic nerve response was abolished by a dorsal column transection (depth, 3-4 mm) or ipsilateral lumbar dorsal rhizotomy (four dorsal roots). This shows that the evoked response recorded from the sciatic nerve in our animals was not travelling, as we expected, through the ventral roots, but rather was conducted antidromically through sensory fibers in dorsal roots.     

Diffusion tensor imaging of somatosensory tract in cervical spondylotic myelopathy and its link with electrophysiological evaluation

Background and contextAbnormal somatosensory evoked potential (SEP) (ie, prolonged latency) has been associated with poor surgical prognosis of cervical spondylotic myelopathy (CSM).PurposeTo further characterize the extent of microstructural damage to the somatosensory tract in CSM patients using diffusion tensor imaging (DTI).Study design/settingRetrospective study.Patient sampleA total of 40 volunteers (25 healthy subjects and 15 CSM patients).Outcome measuresClinical, electrophysiological, and radiological evaluations were performed using the modified Japanese Orthopedic Association (mJOA) scoring system, SEP, and cord compression ratio in anatomic magnetic resonance (MR) images, respectively. Axial diffusion MR images were taken using a pulsed gradient, spin-echo-echo-planar imaging sequence with a 3-T MR system. The diffusion indices in different regions of the spinal cord were measured.MethodsComparison of diffusion indices among healthy and myelopathic spinal cord with intact and impaired SEP responses were performed using one-way analysis of variance.ResultsIn healthy subjects, fractional anisotropy (FA) values were higher in the dorsal (0.73±0.11) and lateral columns (0.72±0.13) than in the ventral column of white matter (0.58±0.10) (eg, at C4/5) (p<.05). FA was dramatically dropped in the dorsal (0.54±0.16) and lateral columns (0.51±0.13) with little change in the ventral column (0.48±0.15) at the compressive lesions in CSM patients. There were no significant differences in the mJOA scores or cord compression ratios between CSM patients with or without abnormal SEP. However, patients with abnormal SEP showed an FA decrease in the dorsal column cephalic to the lesion (0.56±0.06) (ie, at C1/2, compared with healthy subjects [0.66±0.02]), but the same decrease was not observed for those without a SEP abnormality (0.67±0.02).ConclusionSpinal tracts were not uniformly affected in the myelopathic cervical cord. Changes in diffusion indices could delineate focal or extensive myelopathic lesions in CSM, which could account for abnormal SEP. DTI analysis of spinal tracts might provide additional information not available from conventional diagnostic tools for prognosis of CSM.     

早期手术减压对损伤脊髓caspase-3表达的影响

目的探讨大鼠脊髓损伤后不同减压时间对大鼠脊髓细胞caspase-3表达的影响。方法将动物分为:大鼠脊髓挫伤即刻手术减压组(A组),大鼠脊髓挫伤2小时手术减压组(B组),大鼠脊髓挫伤8小时手术减压组(C组),大鼠脊髓挫伤24小时手术减压组(D组)。手术后1、3、7、14、28天对脊髓损伤区进行细胞凋亡caspase-3蛋白表达的测定(免疫组化法),采用计算机图像分析技术,进行定量分析。并用行为学和电生理检查观察大鼠功能恢复情况。结果A、B、C、D四组中均发现凋亡caspase-3蛋白阳性表达细胞,图象分析发现,各组凋亡细胞caspase-3免疫反应阳性细胞表达顺序为D>C>B>A,与大鼠后肢功能恢复有平行的变化趋势。结论大鼠脊髓损伤早期手术减压能抑制脊髓损伤后的细胞凋亡,促进大鼠后肢功能恢复。