磁刺激运动诱发电位体感诱发电位在脊髓及神经根病变定位诊断中的价值

目的:探讨磁刺激运动诱发电位(mMEP)及电刺激体感诱发电位(SEP)在脊髓及神经根病变定位诊断中的价值.方法:将122例经影像学检查证实的患者根据病变部位分为以下三组:腰骶神经根病变组(Ⅰ组),胸腰骶髓病变组(Ⅱ组),颈髓及颈神经根病变组(Ⅲ组),采用丹麦Keypoint型肌电诱发电位仪,对上述患者进行下肢胫后神经磁运动诱发电位(mMEPt)、电刺激胫后神经体感诱发电位(SEPt)及上肢正中神经短潜伏期体感诱发电位(SSEPm)检测.结果:SSEPmⅠ组、Ⅱ组各1例异常,Ⅲ组异常49例(阳性率为96.1%);SEPt 89例异常(阳性率为72.9%),三组之间阳性率经χ2检验差异无显著意义(P>0.05),与SSEPm比较,两者之间阳性率差异无显著意义(P>0.05);mMEPt 74例异常(阳性率为60.7%),Ⅱ组阳性率最高(83.8%),Ⅰ组仅达45%.结论:对于临床上高度怀疑颈髓及颈神经根病变者,仅需作SSEPm便可为临床提供有价值的电生理指标,而不必再作mMEPt及SEPt;单独SEPt 对脊髓病变没有定位诊断价值,而mMEPt不仅能提示脊髓病变的可能部位,对病变局限在脊髓腹侧者也适用; 相当一部分腰骶神经根病变者mMEPt正常,其原因有待进一步研究.     

94例腰椎间盘突出症的体感诱发电位

应用皮肤电极刺激，针电极记录的体感诱发电位，检查９４例腰椎间盘突出患者的胫后神经和节段性（根性）皮神经刺激时的皮层电位，并以５０例正常人作对照，结果发现患者的异常率为８４％，其中Ｌ（４·５）突出者异常率为７１％，Ｌ５·Ｓ１突出者异常率为６１．５％。认为体感诱发电位检查是一种判定腰骶神经根损伤的可靠方法。     

腰椎间盘脱出患者EMG、NCV、SEP联合检测的意义

目的：观察腰椎赣肋痈出患者神经根损害的神经电生理表现。方法：对451例临床确诊的腰椎间盘脱出患者的针电极肌电图（EMG）、神经传导速度（NCV）、体感诱发电位（SEP）进行分析。结果：EMG异常298例（66.1%)，均进行手术治疗，胫神经H反射异常165例（36.6%)；NCV异常16例（3.5%)，提示同时伴有周围神经病；SEP异常372例（82.6%)，以P40潜伏期延长为特点，而3例合并脊髓压迫的患者主要为波幅降低或未引出，结论：EMG、NCV、SEP三项联合检测，不仅可以提高腰椎间盘脱出患者神经根损害电生理检测异常率，还可以对神经根损害程度，范围以及对周围神经，脊髓损害等提供可靠的诊断依据。     

体感诱发电位磁共振对脊髓炎的定位诊断价值对比研究

目的：比较体感诱发电位(SEP)和脊髓磁共振(MRI)检查对视神经脊髓炎(NMO)和急性横贯性脊髓炎(ATM)病人进行定位诊断的价值。方法：对21例临床确诊为NMO和36例ATM病人的SEP和MRI检查结果进行回顾性分析，比较其定位符合率。结果：①ATM组病人MRI以胸髓损害为主，NMO组病人以颈胸段脊髓联合损害为主；②ATM组病人SEP主要表现为N20正常、P40异常，而NMO组病人则表现为N20和P40均异常；当病变位于颈髓时，NMO组SEP与MRI的定位符合率为94．1％，ATM组为78．6％；当病变位于胸髓时，ATM组为100％，NMO组为66．7％。结论：在NMO和ATM病人中，SEP提示的神经电生理异常部位基本与MRI所证实的病变部位相吻合。     

胫后神经脊髓体感诱发电位的起源及其临床应用

通过刺激健康成人胫后神经 ,分别于腰骶段、下胸段和颈段脊髓表面或脊椎皮肤表面记录的体感诱发电位 (ＳＥＰ)的类型、起源和临床应用 ,一直是临床神经电生理工作者所注目的重要课题。经过 30余年的努力 ,ＳＥＰ的研究和应用已有很多进展 ,兹综述如下。1　腰骶部体感诱发电位的类型和起源通过刺激健康成人下肢周围神经 ,采用表面电极 ,可以在腰骶椎皮肤表面记录到由两个潜伏期不同的阴性波组成的ＳＥＰ ,其中第一个阴性波的潜伏期随着记录部位向第 12胸椎移动而不断延长 ,而第二个阴性波的潜伏期在腰骶椎随着记录部位的不同而变化不大。统计…     

体感诱发电位与体感诱发电位地形图及其临床应用

体感诱发电位（Somatosensory Evoked Potential,SEP）一﹑概念：即躯体感觉诱发电位,它是给皮肤或末梢神经以刺激,神经冲动沿传入神经通路至脊髓感觉通路﹑丘脑至大脑皮层中央后回感觉区,在刺激的对侧头皮相应部位记录到的电活动。二﹑体感诱发电位的分类：（一）按记录和刺激电极放置部位分类1﹑上肢和下肢体感诱发电位2﹑感觉神经动作电位3﹑节段性诱发电位4﹑三叉神经体感诱发电位5﹑其他脑干诱发电位或反射6﹑膈神经和肋间神经诱发电位7﹑食管﹑直肠脑诱发电位8﹑二氧化碳激光痛觉诱发电位9﹑外阴部诱发电位10﹑     

帕金森病患者正中神经和胫神经体感诱发电位研究

目的:同时观察帕金森病患者正中神经和胫神经体感诱发电位的异常并推测其发生机制。方法:选择30名帕金森病患者和20名健康对照者,刺激正中神经,记录顶叶体感诱发电位的N20、P25、N30波,额叶的P20、N30波的潜伏期和波幅。刺激胫神经,记录顶叶体感诱发电位的P40、N50、P60波的潜伏期和波幅。结果:帕金森病患者上肢额叶N30和下肢N50波幅明显降低(P<0·05)。结论:帕金森病患者上下肢SEP同时出现异常是黑质纹状体系统多巴胺缺乏的结果,下肢N50波幅比上肢N30与临床症状的严重性更有相关性。     

兔腰骶神经根牵拉的微循环和体感诱发电位变化的研究

目的建立一种不同程度的腰骶神经根牵拉损伤动物模型,探讨脊髓神经根牵拉损伤后微循环和电生理改变。方法将40只中国大白兔随机分为对照组、轻度牵拉组、中度牵拉组和重度牵拉组。全椎板切除显露双侧荐1神经根,用测力神经根拉钩分别以不同的拉力造成神经根的牵拉性损伤。行体感诱发电位监测神经根和骶髓微循环研究。结果轻度牵拉组SEP潜伏期比对照组相稍延长(P>0.05),神经根和骶髓微血管密度轻度增加;中度牵拉组SEP潜伏期明显延长(P<0.05),去除牵拉后潜伏期接近正常(P>0.05),神经根和骶髓微血管密度明显增加;重度牵拉组SEP潜伏期明显延长(P<0.01),去除牵拉后潜伏期稍缩短,和对照组仍存在显著性差异(P<0.05),神经根和骶髓微血管密度轻度增加。结论以拉力为参数可以稳定的建立不同程度的腰骶神经根牵拉性损伤动物模型,微血管密度和SEP可以较好的衡量神经根和脊髓的损伤程度。     

短潜伏期体感诱发电位在肋间血管神经转位脊髓神经根桥接治疗截瘫中的诊断价值

目的 :对 31例截瘫患者采用肋间血管神经转位植入桥接损伤段脊髓和神经根的方法进行治疗。方法 :用下肢体感诱发电位对手术前后的病人进行检测。结果 :发现术前仅有 13例患者出现马尾电位 (CE)波 ,术后 31例患者均能引出CE ,N2 8,P4 0 波。结论 :下肢体感诱发电位对此手术具有重要的临床意义。     

刺激犬踝部胫后神经的脊髓下胸段、腰段体表诱发电位的观察

本文报告了刺激犬左踝胫后神经用双极表面电极,在下胸段、腰段(T9-L6)棘突间隙记录脊髓体表诱发电位的正常波形,以及对不同记录节段的电位潜伏时,幅度值进行的比较。 实验结果表明,刺激胫后神经在下胸段与腰段记录出以负(N)、正(P)双相为主的电位反应。整个记录节段的N波较稳定,P波在胸段变化较大;电位反应幅度在L_1-L_4节段较大,其中L_3-L_2节段幅度最大,N波为0.89μv、P波为0.91μv,反应持续时间也较长,而在L_1-L_4节段上、下各节段电位反应偏低,并且越向头侧端电位幅度递减至消失。峰值潜伏期变化较有规律,差异小,即越向头侧端潜伏期越长。     

65例颈椎型脊髓病体感诱发电位分析

目的研究颈椎型脊髓病皮质体感诱发电位（ＳＥＰ）变化。方法对６５例颈椎型脊髓病患者和２６例正常人进行正中神经和胫后神经刺激的ＳＥＰ对照研究，并对１０例患者作治疗前后对照观察。结果本组异常率为４５％，主要表现为各波替伏期和波间期（Ｎ２０—Ｐ２５，Ｐ２５—Ｎ３５，Ｐ４０—Ｎ４５）延长，且下肢的延长更加明显，部分患者出现波形分化不良。经保守治疗后６例正常，２例好转，且ＳＥＰ的好转先于临床的改善。结论ＳＥＰ对评判颈椎型脊髓病的脊髓传导功能具有重要的意义，且有助于临床预后的评价。     

SEP、EMG监测在腰骶部椎管内病变术中的应用

目的：探讨体感诱发电位（SEP）及肛周肌电图（EMG）监测在腰骶部椎管内病变显微切除术中的作用和疗效评价。方法：对75例患者进行显微手术切除腰骶管病变术中作胫后神经刺激,在相关头皮记录SEP和腰骶部脊神经所支配的肛门外括约肌作EMG监测,并与麻醉后、手术开始前的记录进行比较。术中SEP以潜伏期延长10％或波幅下降50％作为预警信号,EMG以出现异常高电压作为预警参考值。结果：75例患者中,62例（83％）术中SEP监测异常者于病变切除后潜伏期缩短超过5％和（或）波幅上升超过20％;10例（13％）无明显变化;仅3例SEP监测显示潜伏期延长和波幅下降,术中均作成功预警,调整手术策略后,1例恢复至术前水平,2例明显改善。55例（73％）患者术中肛周EMG记录到不同程度的异常高电压,均根据情况调整手术方案。结论：腰骶部椎管内病变切除术中应用SEP、EMG监测可以预防和减少神经损伤,并能对手术疗效进行即时评价。     

Comparative study of evoked potentials in multiple sclerosis and neuro-Beh?et's syndrome

We studied somatosensory evoked potentials (SEPs) and brainstem auditory evoked potentials (BAEPs) in Japanese patients with multiple sclerosis (MS) and those with neuro-Behcet's disease (NB). Abnormal cortical P37 of posterior tibial nerve SEPs or cervical N13 of median nerve SEPs were more frequently found in the MS patients than in the NB patients. On the other hand, prolongation of the central conduction time of median nerve SEPs or abnormal BAEPs were more common in NB than in MS. The present data showed that lesions were mainly present in the spinal cord in MS and in the brainstem in NB. SEPs and BAEPs were considered of great value for detecting the involvement of the central nervous system in MS and NB and distinguishing between these diseases.     

Sequential involvement of the nervous system in subacute combined degeneration

Purpose

Subacute combined degeneration (SCD) involves progressive degeneration of the spinal cord, optic nerve, and peripheral nerves. Vitamin B12 (VB12) is a co-factor in myelin synthesis. Because each cell that constitutes the myelin component in the central nervous system and peripheral nervous system is different, it is improbable that these cells undergo simultaneous degeneration. However, the sequence of degeneration in SCD has not been established.

Materials and Methods

In this study, we analysed medical records and electrophysiological data of patients who showed neurological symptoms and whose serum VB12 levels were lower than 200 pg/mL.

Results

We enrolled 49 patients in this study. Their mean VB12 level was 68.3 pg/mL. Somatosensory evoked potential (SEP) study showed abnormal findings in 38 patients. Of the 40 patients who underwent visual evoked potential (VEP) study, 14 showed abnormal responses. Eighteen patients showed abnormal findings on a nerve conduction study (NCS). In this study, abnormal posterior tibial nerve SEPs only were seen in 16 patients, median nerve SEPs only were seen in 3 patients, abnormal VEPs only in two, and abnormal NCS responses in one patient. No patient complained of cognitive symptoms.

Conclusion

In SCD, degeneration appears to progress in the following order: lower spinal cord, cervical spinal cord, peripheral nerve/optic nerve, and finally, the brain.     

Vitamin B12 deficiency neurological syndromes: a clinical,MRI and electrodiagnostic study

BACKGROUND: Vegetarianism is an important cause of vitamin B12 deficiency, especially in countries like India. We managed 17 patients with neurological syndrome due to vitamin B12 deficiency in a tertiary care referral teaching hospital which caters to relatively affluent population. AIM: To evaluate neurophysiological and MRI changes in patients presenting with vitamin B12 deficiency neurological syndrome and interpret these is the light of reported autopsy findings. SETTING: Tertiary care referral teaching hospital. METHODS: Patients with vitamin B12 deficiency neurological syndrome diagnosed by low serum vitamin B12 and/or megaloblastic bone marrow were subjected to clinical evaluation and spinal MRI. The neurophysiological tests included nerve conduction studies, tibial somatosensory evoked potential (SEP), motor evoked potential (MEP) and visual evoked potential (VEP) studies. The recovery was defined on the basis of 6 months Barthel Index score into complete, partial or poor. RESULTS: There were 17 patients with vitamin B12 deficiency neurological syndrome, 3 were females and 12 lactovegetarian. The clinical syndrome was that of myelopathy in 8, myeloneuropathy in 5, dementia myelopathy in 3 and neuropathy in 1 patient. All the patients had impaired joint position and vibration sensation in the lower limbs and 4 had in upper limbs as well. Lower limbs were spastic in 13 and upper limbs in 2 patients. Spinal MRI revealed T2 hyperintensity in cervicodorsal region in 6 and cord atrophy in 3 patients. Sural nerve conduction was abnormal in 8 and peroneal conduction in 5 patients. In one patient all sensory nerve conductions were unrecordable but motor conductions were normal. Tibial SEP was abnormal in 12 out of 15 and lower limb MEP in 8 out of 12 patients. P100 latency of VEP was prolonged in 7 out of 13 patients. Right to left asymmetry was present in tibial SEP in 4 and VEP in 2 patients. At 6 months followup 2 patients improved completely, 7 partially and 3 had poor recovery. Clinical recovery correlated with MEP but not with SEP or MRI changes. CONCLUSION: The evoked potential and MRI changes in vitamin B12 deficiency neurological syndrome are consistent with focal demyelination of white matter in spinal cord and optic nerve. Myelopathic presentation is commoner and SEP is more frequently abnormal. The outcome at 6 months correlated with MEP changes.     

Multichannel derived median nerve SEP compared to EEG in patients with vascular cerebral lesions.

In order to compare the sensitivity of multichannel derived median nerve SEP with EEG in vascular cerebral lesions we examined 22 normals and 23 patients. SEP components within the first 50 ms could be divided into main waveform patterns: (1) a W-shaped parietal pattern consisting of N20, P25, N35 and P45 in most cases. (2) a frontal pattern with P20 and N30 as well as possibly detectible N24, P28, P33, N40 and P50. (3) a central P22. Two younger normals showed a V-shaped parietal pattern with N20 and P35, a frontal pattern with P20 and N36, and central P22 with a remarkably long latency. All components could be analysed sufficiently by means of three representative electrode positions (stimulation right/left): P3/P4, C3/C4, and F3/F4, which reduces the expense of recording and analysing considerably. 21 patients (91.3%) showed abnormal results in SEP, whereas 14 patients (60.9%) in EEG. A three channel electrode array can increase the usefulness of SEP and detect cerebral dysfunctions in cerebral lesions in spite of normal EEG under routine examination conditions. Analysis of multichannel derived SEPs during treatment and recovery after stroke and search for the prognostic value in the acute stage of the disease should be done in future.     

Observations of the posterior tibial nerve SEP of patients requiring extradural spinal surgery

The cortical potentials evoked by posterior tibial nerve stimulation were examined in a series of 141 hospital patients requiring extradural spinal surgery. One hundred and five patients were neurologically intact, while in 36 some deficit was present. In the intact subjects, the absolute latencies of the main medium-latency peaks (N30, P40, N50, P60) were found to vary with height and age. There were no additional gender-related differences. The latencies of the deficit group were longer than those of the intact group but only marginally useful as a clinical discriminator; their amplitudes were not significantly lower than those of the intact group. A model for variations in SEP latency is suggested.     

体感诱发电位评价慢性压迫性脊髓症神经功能的病理机制

目的 探讨慢性压迫性脊髓症不同体感诱发电位(somatosensory evoked potential,SEP)变化对应的病理学机制.方法 20只SD大鼠经后路手术、颈椎管内(C5～C6水平)植入吸性聚氨酯胶片,该植入体在硬膜外逐渐吸水膨胀,形成对脊髓的慢性持续压迫.术前和造模后6个月检测SEP,并对慢性压迫脊髓行Micro-CT、组织学(HE染色)和组织化学(FLB染色)检测.结果 20只造模大鼠脊髓均出现侧后方明显压迫性形态学改变,Micro-CT显示脊髓灰质和白质扭曲变形.依据SEP变化分为Ⅰ(n=6)、Ⅱa(n=5)、Ⅱb(n=4)、Ⅲ(n=5)、Ⅳ(n=0)5类.SEP异常者脊髓后索髓鞘FLB染色显著减少(SEP异常:106±27;SEP正常:121±8;P=0.036),Micro-CT显示脊髓后索对比剂密度明显增加(SEP异常:95±5;SEP正常:87±6;P=0.041),后角内神经元也明显较少[SEP异常:(21±8)/mm2;SEP正常:(29±6)/mm2;P＞0.05].病理学上,SEP-Ⅰ型表现为脊髓中央管扩大;Ⅱa型表现为灰质内出血、静脉扩张和中央管缩小;Ⅱb型表现为灰质、白质排列紊乱,血管增生;Ⅲ型表现为神经元明显减少、白质-灰质结构不清,基质海绵样变.结论 慢性压迫性脊髓症不同类型的SEP变化反映了脊髓后索和灰质神经元损伤的严重程度,SEP作为脊髓功能预后评估的判断指标具有相应的病理学特征.     

Somatosensory evoked potentials in man: differentiation of spinal pathways responsible for conduction from the forelimb vs hindlimb

This review suggests that a previously unrecognized spinal cord pathway may be of major importance in the conduction of the somatosensory evoked potential (SEP) from the lower limb in Man. The nerve fiber type activated by a "typical" peripheral nerve stimulus used in studying the SEP will activate the posterior tibial nerve or median nerve predominantly at group I threshold. Group I fibers subserve limb proprioception. Therefore the spinal cord pathways subserving limb position sense will be the same pathways activated by a peripheral nerve stimulus used to evoke an SEP. A relatively newly recognized pathway involved with limb position sense from the lower limb is located in the dorsal portion of the lateral funiculus of the spinal cord whereas pathways subserving limb position sense in forelimb involve predominantly the dorsal column pathways. It is suggested that the dorsal columns play no major role in limb position sense from the lower limb in Man and therefore, the dorsal columns play no major role in the conduction of activity from the lower limb involved with the generation of an SEP.