Evaluation of spinal evoked potentials: a model for assessment of spinal cord function in isolation

Spinal evoked potentials were recorded from the dorsal columns of in vitro mouse hemicord preparations. The response of these potentials to different periods of hypoxia was studied. A decrease in amplitude of the potential to 50% and 10% of pre-hypoxia reference occurred after 3.19 ± 1.36 and 7.3 ± 2.97 min, respectively. Complete recovery of the potential was seen in specimens exposed to 5 and 10 min of hypoxia. Incomplete recovery occurred with exposure to longer periods of hypoxia. In preparations that remained isoelectric for less than 5 min total recovery was seen.     

1～14岁正常儿童胫后神经体感诱发电位正常值及其特点

目的：探讨正常儿童胫后神经（PTN）体感诱发电位（SEP）的特点及正常值。方法：对121名正常儿童进行PTN—SEP检测,分析各波的特点及各波参数随年龄变化规律。结果：PTN—SEP随年龄增长,波幅增高,使波容易辨认,波幅在个体问变异较大。左右双侧对应波的潜伏期（PL）和峰间期（IPL）比较差异无显著意义（P〉0．05）,各组男女间PL和IPL无性别差异（P〉0．05）。外周神经电位的腰髓电位（LP）、马尾电位（cE）、胭窝电位（PF）等3个波的潜伏期随年龄增长PI。延长,而P40和N45等皮层电位的PL在8岁前变化则不明显（相邻组间P〉0．05）,8岁后延长明显。PF-T12的IPL也随年龄增长而延长（相邻组间P〈0．05）;而T12-P40IPL3岁组较1岁组延长,但差异不明显,以后随年龄增长而缩短,6岁组达成人值。结论：儿童PTN—SEP的正常值按年龄组划分是完全必要的。由于各波PL受身长的影响大,因此绝对PL不宜作为PTN—SEP的异常标准。PTNSEP是评价小儿躯体感觉通路、脊髓、脑干和大脑功能的客观指标,具有较大的临床实用价值。     

下调PTEN基因对全脑缺血大鼠学习记忆能力和CREB表达的影响

目的:探讨下调第10号染色体同源丢失性磷酸酶张力蛋白基因(Phosphatase and tensin homolog deleted on chromosome ten,PTEN)对全脑缺血再灌注大鼠学习记忆能力及转录因子环磷酸腺苷反应元件结合蛋白(cAMP response element- binding pro...     

Predicting long-term outcomes after cardiac arrest by using serum neutrophil gelatinase-associated lipocalin

Objectives

Neutrophil gelatinase-associated lipocalin (NGAL) is secreted by various tissues in pathologic states. Previous studies reported that post-cardiac arrest serum NGAL levels correlate with short-term neurologic outcomes and survival. The aim of this study was to examine the associations between NGAL levels post-cardiac arrest and long-term outcomes and survival.

肋间神经植入损伤侧脊髓的电生理改变

目的通过神经示踪方法(MEP)和脊髓电生理(SEP)检测探讨该方法对脊髓损伤修复的可行性,客观评价其价值。方法本实验共设3组:A组(正常对照组)、B组(制作成脊髓半切损害模型将肋间神经植入缺损的脊髓处)、C组(在脊髓半切损害模型的脊髓缺损处植入可吸收的明胶海绵)。结果B组经移植重建后,示踪剂注射处显色显示沿神经束向远、近端顺向和逆向运输,并以顺向显色较为明显。3个月后引MEP和SEP测定。B组与C组相比较,脊髓电生理功能有明显改善,其潜伏期和波幅均有不同程度的恢复。统计学处理(P<0.01)。结论纵观脊髓损伤肋间神经移植不仅可诱导和促进脊髓再生,而且再生的轴突可沿着肋间神经桥延伸到较远的距离。MEP和SEP在此方面可起到较为客观的评价作用。     

Dynamic Brain Topography of Somatosensory Evoked Potentials and Equivalent Dipoles in Response to Graded Painful Skin and Muscle Stimulation

The differential effects of painful stimulation of skin vs. muscle on the cerebral electrophysiology have been poorly described. This study examined the somatosensory evoked potentials (SEPs) and the associated dipole models of non-painful and graded painful electrical stimulation applied to the skin and muscle in 20 healthy subjects. With the psychophysical stimulus-response functions determined, the skin stimulation showed a steeper slope than muscle stimulation. For both types of stimulation, the SEPs indicated a similar temporo-spatial activation sequence: F4/N90-P4/P95, Fc2/N135, Cz/P250, Cz/P300, and Cz/N460. The SEP amplitudes increased significantly with the stimulus intensities in these components. The peak SEP latencies of skin stimulation were in general shorter than that of muscle stimulation. The SEP amplitudes to skin stimulation were significantly larger than those caused by muscle stimulation at every stimulus intensity level, except the early mid-latency component. In this case, muscle stimulation caused higher amplitudes over the contralateral parietal-frontal sites. For both types of stimulation, the topographic maps were quite similar. Equivalent dipole modeling revealed identical site parameters (<1.0 cm) between skin and muscle stimulation. However, the electrical skin stimulation did not correlate with the pain intensity. Pain intensity, in contrast, was uniquely associated with the Cz/P250 amplitudes for the muscle stimulation. It is concluded that non-nociceptive and nociceptive electrical stimuli applied to skin and muscle are processed in the common cerebral areas, but exhibit differential SEP effects.     

A Visual study of surface potentials and Laplacians due to distributed neocortical sources: Computer simulations and evoked potentials

Summary A "picture book" of surface potentials, Laplacians, and magnetic fields due to distributed, neocortical sources is presented. The mathematically simulated data is based on 4200 current sources at the macrocolumn scale. Estimated scalp surface maps are based on the three-concentic spheres model of the head. Emphasis is placed on the effects of sampling with a limited number of electrodes, the choice of reference electrode, and the use of the spline Laplacian to improve spatial resolution. The spline Laplacian is applied to median and ulnar nerve somatosensory evoked potentials and to auditory evoked potentials including P300. Substantial improvement in spatial resolution over conventional methods is obtained. The implementation of practical high resolution EEG systems based on the spline Laplacian is considered.The authors greatfully acknowledge the technical assistance of Chris Fritton, Laurie Orth, and Chiraprakash Nayak. This research was supported by NIH grant RO1 NS24314.Invited paper, Submitted to Brain Topography, July, 1991     

复合自适应滤波器用于体感诱发电位信噪比的提高

本研究以可靠、快速提取体感诱发电位为目标,试图解决相干叠加方法既费时又不能反映体感诱发电位时变特征的缺点。运用以自适应噪声减法器和自适应增强器为基础构造的复合自适应滤波器提取体感诱发电位。仿真实验表明,运用复合自适应滤波器可实现从强噪声背景中快速提取体感诱发电位,能更快地识别体感诱发电位的潜伏期及幅值,并且系统性能稳定。     

体感诱发电位与感觉神经动作电位对于臂丛神经(节前节后)损伤的诊断价值

本文报告4例臂丛神经损伤进行SEP,SNAP及手术的对比观察结果,臂丛神经损伤(节前/节后)与神经生理SEP和SNAP波幅降低或消失有关,提示:SEP与SNAP的共同应用对于臂丛神经损伤定位(节前/节后)有较高的应用价值。     

脑梗死急性期下肢运动功能恢复与体感诱发电位变化的关系

目的探讨体感诱发电位 (SEP)评定和预测脑梗死急性期患者下肢运动功能恢复的价值。方法按照脑血管疾病分类标准 ,选择脑梗死急性期患者 19例 (男性 13例、女性 6例 )作为病例组。同时 ,选择 18例非神经系统损伤患者 (男性 11例、女性7例 )作为对照组 ;在发病 7d内 ,检测并比较两组患者SEP的潜伏期和波幅值的改变 ;对病例组患者 ,于住院 3 0d时再次进行下肢SEP检测 ,并在两次SEP检测的同时进行下肢Fugl Meyer评定 (FMA) ,以对SEP潜伏期与FMA评分进行相关分析。 结果两组患者的下肢SEP潜伏期和波幅值差异有显著性意义 ;病例组患者住院 3 0d时的SEP潜伏期值较入院时明显缩短 (P <0 .0 1) ,并与下肢FMA评分有相关性 (r =0 .741— 0 .792 ,P <0 .0 1) ,但住院 3 0d时的SEP波幅值改变与入院时比较无显著性差异。结论脑梗死急性期患者入院时和住院 3 0d时下肢SEP潜伏期值的改变有统计学意义 ,并与FMA评分有相关性 ,说明SEP潜伏期值对预测脑梗死急性期患者下肢运动功能恢复有一定参考价值 ,但SEP波幅的敏感性较差。