麻醉与低温对诱发电位的影响──利用诱发电位对中枢神经系统功能进行监护

：脑电诱发电位可以用于监护低温手术和麻醉对病人中枢系统的影响，与脑电相比，诱发电位更具特异性。本文介绍了巴比妥盐和乙醚、环丙烷、一氧化氮等吸入类麻药对诱发电位的影响及低温对体感、视觉和听觉诱发电位的影响，并比较了各种诱发电位监护低温状态的效果。认为需要选用既能有效地反映麻醉状态又能有效地反映温度变化的诱发电位模式，以有效地利用诱发电位监护低温手术中的中枢神经系统功能。     

脊椎体感诱发电位中的高频抑制

本文介绍了脊椎体感诱发电位的记录装置及记录方法,并在家兔脊椎处体表记录到了体感诱发电位波形。研究了高频脉冲电刺激所引起的神经兴奋对诱发电位刺激所引起的神经兴奋在脊髓发生的影响,证明了高频抑制在脊髓就能发生。同时也阐明了体表记录的脊椎体感诱发电位完全能反映出脊髓中高频抑制这样的电活动,这对理解体表记录的诱发电位所能表示的生理信息量是很有意义的。     

应用连续小波变换提取脊柱手术中脊髓功能特征参数的研究

在脊柱外科手术中,为防止脊髓神经功能损伤进行术中脊髓功能监护十分必要。本研究以特发性脊柱侧弯矫形手术中脊髓功能的电生理监护特征参数提取技术为目标,试图解决监护参数在时域参数变异性较大、容易受干扰的问题。运用连续小波变换方法对手术中采集的体感诱发电位分析处理,提取信号在时频域的三个新的特征参数。通过本研究表明,在脊柱手术监护中,运用连续小波变换获得的时频域特征参数比单纯在时域分析参数具有更小的变异系数。因此时频域特征分析参数比单纯时域的幅值和潜伏期分析更稳定和可靠。在脊柱手术中如果应用时频监护参数可能会更有效地避免脊髓损伤。     

脊柱外科手术中脊髓功能的监护

脊柱外科手术中,由于加压、推移力、内固定器械置入等外加因素造成对神经的压迫,可能导致脊髓功能的损伤.脊髓监护可以及时发现手术中的不当操作和可能出现的损伤并及早进行纠正和补救,因而有效地降低脊柱外科手术中脊髓功能的损伤.术中脊髓监护技术经过几十年的发展,由传统的唤醒方法发展到今天比较完善的诱发电位监护技术.回顾了脊髓监护技术的发展及其在脊柱外科手术中的应用,并介绍了近年来脊髓监护领域研究的新进展.     

脊柱外科术中体感诱发电位监测应用研究

众所周知，脊柱外科手术由于多数操作累及脊髓和神经，极易造成脊髓损伤导致病人瘫痪，因此属于高风险、高难度手术范畴。近年来，由于体感诱发电位术中监测技术的应用，     

术中经颅电刺激运动诱发电位和皮层体感诱发电位联合监护与唤醒试验判断脊髓功能

目的 探讨术中经颅电刺激运动诱发电位(TES-MEP)和皮层体感诱发电位(CSEP)联合监护与唤醒试验判断脊髓功能的作用.方法 2006年7月至2010年3月中山大学附属第一医院脊柱外科脊柱手术中同时实施TES-MEP和CSEP联合监护426例,并对术中出现阳性和仔细检查后原因不明或纠正手术操作后仍没有恢复的23例进行唤醒试验.根据术中联合监护和唤醒试验结果,分别与术后脊髓功能进行比较.结果 联合监护阳性64例(15%),其中51例与脊髓功能符合,另13例不符合.假阳性占3.1%(13/426).本组无假阴性.联合监护判断脊髓功能灵敏度为100%(51151),特异度96.5%(362/375),约登指数0.965.23例唤醒试验中,8例阳性均与脊髓功能符合,没有假阳性.而15例阴性中,与脊髓功能符合9例,不符合6例.唤醒试验判断脊髓功能的灵敏度为57.1%(8/14)、特异度100%(9/9)、约登指数0.571.结论 TES.MEP和CSEP联合监护为目前脊柱外科手术监护的理想选择和首选方法,唤醒试验可用于联合监护真假阳性鉴别的检测.     

术中经颅电刺激运动诱发电位和皮层体感诱发电位联合监护与唤醒试验判断脊髓功能

目的 探讨术中经颅电刺激运动诱发电位(TES-MEP)和皮层体感诱发电位(CSEP)联合监护与唤醒试验判断脊髓功能的作用.方法 2006年7月至2010年3月中山大学附属第一医院脊柱外科脊柱手术中同时实施TES-MEP和CSEP联合监护426例,并对术中出现阳性和仔细检查后原因不明或纠正手术操作后仍没有恢复的23例进行唤醒试验.根据术中联合监护和唤醒试验结果,分别与术后脊髓功能进行比较.结果 联合监护阳性64例(15%),其中51例与脊髓功能符合,另13例不符合.假阳性占3.1%(13/426).本组无假阴性.联合监护判断脊髓功能灵敏度为100%(51151),特异度96.5%(362/375),约登指数0.965.23例唤醒试验中,8例阳性均与脊髓功能符合,没有假阳性.而15例阴性中,与脊髓功能符合9例,不符合6例.唤醒试验判断脊髓功能的灵敏度为57.1%(8/14)、特异度100%(9/9)、约登指数0.571.结论 TES.MEP和CSEP联合监护为目前脊柱外科手术监护的理想选择和首选方法,唤醒试验可用于联合监护真假阳性鉴别的检测.     

诱发电位与脊髓损伤

诱发电位技术可反映脊髓感觉和运动传导通路完整性。许多研究证明在脊髓损伤的程度、部位及预后的判断及脊柱手术时监护脊髓功能等方面,诱发电位技术为一项客观评价指标。本文就诱发电位在脊髓损伤方面的研究动态及应用前景作一综述。     

麻醉与低温对诱发电位的影响—利用诱发电位对中枢…

脑电诱发电位可以用于监护低温手术和麻醉对病人中枢系统的影响，与脑电相比，诱发电位更具特异性。本介绍了巴比妥盐和乙醚、环丙烷、一氧化氮等吸入类麻药对诱发电位的影响及低温对体感，视觉和听觉诱发电位的影响，并比较了各种诱发电位监护低温状态的效果，认为需要选用既能有效地反映麻醉状态又能有效地反映温度变化的诱发电位模式，以有效地利用诱发电位监护低温手术中的中枢神经系统功能。     

经腹脊髓损伤后体感诱发电位变化的实验研究

目的：利用犬作经腹脊髓损伤在不同压强下观察体感诱发电位（SEP）的变化。方法：记录12只狗在不同的损伤强度（32、36、40kPa）下的脊髓诱发电位（SCEP）和皮层体感诱发电位（CSEP）,并比较了它们之间的改变。结果：狗的脊髓受压后SCEP和CSEP的波幅降低,潜伏期延长。其改变有显著性意义,而P波和N波之间改变无显著性差别。结论：对脊髓损伤的敏感性SCEP比CSEP相对较高,对脊髓损伤预后的评估CSEP比SCEP更有价值。     

Comparison of time-frequency analysis techniques in intraoperative somatosensory evoked potential (SEP) monitoring.

Somatosensory evoked potentials (SEPs) can be monitored during spinal surgery to prevent possible spinal cord injury. In order to improve the reliability of SEP monitoring, an investigation of the application of various time-frequency analysis (TFA) techniques to detect both temporal and spectral changes in SEP waveforms was conducted. SEP signals from 15 scoliosis patients were analysed using various methods. The time-frequency distributions (TFDs) computed using these methods were assessed and compared. The most appropriate TFA technique may depend on the type of SEP signal, Short term Fourier transform (STFT) with a 20 point length Hanning window probably provides the best result for SEP signals.     

Adaptive signal enhancement of somatosensory evoked potential for spinal cord compression detection: an experimental study

The objective of this study was to assess the efficacy of adaptive signal enhancement (ASE) as a means of indicating intraoperative spinal cord impingement. ASE technique was used to determine the changes in the somatosensory evoked potential (SEP) elicited from eighteen rats with varying levels of spinal cord compression. ASE technique was found to be able to effectively extract SEP signals for the detection of spinal cord injury. Furthermore, while the traditional ensemble averaging (EA) technique requires more than 500 trials for meaningful signal processing in severe noisy SEP recordings, the ASE method required only 50 trials to provide similar information. Because of its fast and reliable SEP detection, the ASE method is ideal for spinal cord monitoring in the clinical setting.     

多模式神经电生理监测在椎管内占位手术中的应用

目的　探讨体感诱发电位(CSEP)、经颅电刺激运动诱发电位(TES-MEP)与自由及激发肌电图（EMG）多模式联合监测技术在脊柱椎管内占位手术中应用的价值。 方法　对47例脊柱椎管内占位患者(颈椎4例,胸椎14例,胸腰段13例,腰椎13例,骶椎3例)行占位病变切除术中采用CSEP+TES-MEP+自由EMG+激发EMG监护。 结果　①CSEP和 TES-MEP：监测成功率各为100%和93.6%;阳性率分别为19.1%和17.0%;联合监测假阴性率及假阳性率均为0%;10例诱发电位阳性均与手术操作有关,8例及时报警采取措施后渐恢复,2例MEP阳性未能恢复,术后肌力下降;6例CSEP改善,术后症状好转。②自由和激发EMG：34例患者术中出现自由EMG,其中1例马尾神经严密包裹病变的患者,术后小便功能异常,术后渐恢复。 结论　①椎管内占位术中联合运用CSEP和TES-MEP监测,排除各种干扰因素后,能准确地反映术中脊髓功能状况;②术中自由及激发EMG监测可准确探查和鉴别占位病变神经组织分布,实时反映神经受激惹情况,预防医源性神经损伤。     

Intraoperative monitoring of spinal cord function in spinal and spinal cord surgery

It has become essential to monitor spinal cord function during operations which may involve the risk of stretching, compressing, or injuring the spinal cord, or compromise its blood supply. The recordings of sensory and motor functions include the spinal cord-evoked potential (SCEP), motor-evoked potential (MEP), and somatosensory-evoked potential (SEP). Each of these recordings is not sufficient as a single modality to evaluate the integrity of spinal cord function, so they are used in combination. In particular, to prevent and detect early motor disturbance, the MEP is widely used, which has the advantages of the lowest invasiveness and greatest case of setting. Although spinal cord monitoring is conducted by surgeons, anesthetists, and medical technologists, it should preferably be performed by those routinely engaged in neurophysiological examinations including intraoperative monitoring. Its success depends largely on good coordination and mutual trust between surgeons, anesthesiologists, operative nurses, and clinical engineers, as well as the development of individual expertise.     

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。     

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.     

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。     

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.     

Convergence characteristics of two algorithms in non-linear stimulus artefact cancellation for electrically evoked potential enhancement

Somatosensory evoked potentials (SEPs) are a sub-class of evoked potentials (EPs) that are very useful in diagnosing various neuromuscular disorders and in spinal cord and peripheral-nerve monitoring. Most often, the measurements of these signals are contaminated by stimulus-evoked artefact. Conventional stimulus-artifact (SA) reduction schemes are primarily hardware-based and rely on some form of input blanking during the SA phase. This procedure can result in partial SEP loss if the tail of the SA interferes with the SEP. Adaptive filters offer an attractive solution to this problem by iteratively reducing the SA waveform while leaving the SEP intact. Owing to the inherent non-linearities in the SA generation system, non-linear adaptive filters (NAFs) are most suitable. SA reduction using NAFs based on truncated second-order Volterra expansion series is investigated. The focus is on the performance of two main adaptation algorithms, the least mean square (LMS) and recursive least squares (RLS) algorithms, in the context of non-linear adaptive filtering. A comparison between the convergence and performance characteristics fo these two algorithms is made by processing both simulated and experimental SA data. It is found that, in high artefact-to-noise ratio (ANR) SA cancellation, owing to the large eigenvalue spreads, the RLS-based NAF is more efficient than the LMS-based NAF. However, in low-ANR scenarios, the RLS-and LMS-based NAFs exhibit similar convergence properties, and the computatioal simplicity of the LMS-based NAFs makes them the preferred option.     

Evoked potential changes in ischaemic myelopathy

Somatosensory evoked potentials are employed in the intraoperative monitoring but there is paucity of information about the motor evoked potentials (MEP) in spinal cord ischaemia. Two patients aged 9 and 4 years developed paraplegia following surgery for coarctation of aorta. The aortic cross clamping time in these patients was 100 min and 30 min. respectively. The patient with longer clamping time had flaccid paraplegia and lower limb MEPs were not recordable; whereas the patient with shorter clamping time had spastic paraparesis and prolonged CMCT to right lower limb. The latter patient improved significantly. Tibial SEPs were normal in both the patients. Our results suggest that MEP may have a greater role than SEP in documenting and prognosticating ischaemic myelopathy.