单纤维肌电图在68例运动神经元病患者中的研究

目的　研究运动神经元病 (MND)患者的单纤维肌电图 (SFEMG)改变、病理生理机制及临床意义。方法　对 6 8例 (男 4 3例 ,女 2 5例 )经病史、临床表现和神经电生理检查测定证实的MND患者进行了伸指总肌SFEMG测定 ,并与年龄匹配的正常人对照。结果　所有患者感觉神经传导速度测定均正常 ,肌电图为广泛神经源性损害。SFEMG检查发现 :颤抖值 (jitter)为 30～ 178μs,平均 (80 2± 32 6 ) μs ;jitter>5 5 μs占 5 0 %～ 10 0 0 % ,平均 6 0 6 %± 2 9 0 % ;阻滞 (block)所占百分比为 0 0 %～90 0 % ,平均 2 9 3%± 30 0 % ;纤维密度 (FD)为 1 4～ 4 0 ,平均 2 6± 0 6。其中 5 1例确诊和拟诊的肌萎缩侧索硬化患者jitter增宽、block和FD增高最明显。还发现伸指总肌肌无力的程度与jitter增宽和block百分比呈明显的负相关。结论　SFEMG的异常改变在确诊患者组最明显 ;jitter增宽、block百分比升高和FD增高与肌肉无力的严重程度呈明显的负相关 (P <0 0 0 1) ;jitter增宽、block百分比升高和FD增高反映进行性失神经、神经再生和神经肌肉接头处的传递情况     

常规肌电图和单纤维肌电图在盆底疾病中的应用

本文三组患者均检查耻骨直肠肌，肛门内外括约肌共１０９８块肌肉，检测６７８８０个运动单位。结果表明：常规肌电图和单纤维肌电图在便秘组、肿瘤术后组和脊髓病变组异常率分别为：８２．２％和９４．７％；６６．７％和７９．２％；９８．４％和１００％。并初步探讨其对盆底疾病的诊断价值。     

运动神经元病的重复电刺激的研究

应用重复电刺激技术检查了４３例运动神经元病患者和２０例脊髓型颈椎病患者。结果发现部分运动神经元病患者有类重症肌无力的肌电图表现，即低频刺激时波幅递减，高频刺激时波幅递增。低频刺激时，波幅的衰减与病程、病型、病情无关，但在有束颤的患者中波幅衰减更明显。提示运动神经元病可能有突触前的损害。     

单纤维肌电图及其临床应用

肌电图(EMG)是检测上、下运动神经元、周围神经、神经肌肉接头以及肌肉整个运动系统功能的一种重要的临床电生理学方法.传统EMG采用同心圆针或单极针电极,主要研究运动单位(MU)内一定数量的、一组肌纤维动作电位(AP)的时空关系;而单纤维肌电图(SFEMG)采用特殊的单纤维针电极,用于研究一个MU内不同肌纤维及其运动终板的电活动[1].现就SFEMG的检测技术及其临床应用进行综述.     

耻骨直肠肌综合征的常规肌电图与单纤维肌电图比较

本文对１０２例耻骨直肠肌综合征的患者均检查耻骨直肠肌及肛门内，外括约肌共３０６块从，检测６１２０个运动单位。结果表明：常规肌电图（ＥＭＧ）和单飨岂电（ＳＦＥＭＧ）在耻骨直肠肌肥厚组和耻骨直肌痉挛组分别为９２．２％（５９／６４）和８６．３％（３３／３８）、６３．２％（２４／３８）。提示ＥＭＧ和ＳＦＥＭＧ对耻骨直肠肥厚症和煌症具有重要诊断价值。     

运动神经元病396例临床分析

运动神经元病（M ND ）是一种病因未明,选择性侵犯脊髓前角运动神经元、脑干运动神经核、大脑运动皮质锥体细胞及锥体束的神经系统变性病。临床表现为上下运动神经元损害的不同组合,特征表现为肌无力和萎缩、延髓麻痹及锥体束征。通常感觉系统不受累。多中年发病,病程为2～6 a ,男多于女,患病比例为1.2～2.5∶1。年发病率为（0.13～1.4）／10万。     

同心圆针电极记录的单纤维肌电图

1单纤维肌电图概述经典的单纤维肌电图(single fiber electromyography,SFEMG)是用特制的单纤维针电极记录来自单个肌纤维的动作电位,通过颤抖(jitter)和纤维密度(fiber density,FD)分别了解神经肌肉接头功能和运动单元内肌纤维再分布情况[1]。前者主要在重症肌无力(myasthenia gravis,MG)等疾病中反映神经肌肉接头受累程度,后者主要反映下运动神经元疾病的神经源性损害后的神经再支配情况。     

糖尿病患者单纤维肌电图分析

目的 探讨糖尿病患者的单纤维肌电图改变特点。方法 测定122例糖尿病患者胫骨前肌的单纤维肌电图,观察颤抖和纤维密度(FD),测定腓神经的运动传导速度(MCV)、感觉传导速度(SCV)。结果 糖尿病患者胫骨前肌的颤抖、FD异常率分别为75％、70％,腓神经的MCV、SCV异常率分别为55％、58％。结论 糖尿病患者存在着广泛的神经病变,单纤维肌电图是诊断神经病变的敏感指标。     

糖尿病患者单纤维肌电图分析

目的探讨糖尿病癌患者的单纤维肌电图改变特点。方法测定122例糖尿病患者胫骨前肌的单纤维肌电图，观察颤抖和纤维密度（FD），测定腓神经的运动传导速度（MCV）、感觉传导速度（SCV）。结果糖尿病患者胫骨前肌的颤抖、FD异常率分别为75%、70%，腓神经的MCV、SCV异常率分别为55%、58%。结论糖尿病患者存在着广泛的神经病变，单纤维肌电图是诊断神经病变的敏感指标。     

Surface electromyography using electrode arrays: a study of motor neuron disease

The use of electromyography (EMG) is limited, particularly in the investigation of children, by the invasive nature of needle electrodes. Surface electrode techniques are an attractive alternative but the detected signals are greatly influenced by volume conductor effects, thus making their interpretation problematic. Using finite element analysis we investigated the relationship between surface potential distribution and motor unit depth, incorporating anisotropic conductivity to model muscle tissue and a range of subcutaneous fat thicknesses. The modeling results were used to analyze data recorded with a 16-channel surface electrode array, from 10 normals subjects and 12 patients with motor neuron disease. Differences in the motor units between the two groups were statistically significant (P < 0.01) and are consistent with reinnervation and increased motor unit territory in the patient group. This noninvasive technique shows promise as a more acceptable alternative to the use of conventional needle electrodes for neurophysiological investigations.     

Activity-dependent changes in impulse conduction of single human motor axons: A stimulated single fiber electromyography study

Objective

The aim of this study is to develop a novel method to assess activity-dependent hyperpolarization in human single motor axons at a constant stimulus frequency by using intra-muscular axonal stimulating single fiber electromyography (s-SFEMG).

Methods

We performed s-SFEMG in the extensor digitorum communis (EDC) muscle of 10 normal subjects, and measured changes in latencies for single muscle fiber action potentials (MAPs) during 500 stimuli delivered at 5, 10 and 20 Hz. The data were analyzed with a repeated measurement analysis, and multiple comparisons were performed.

Results

A total of 585 MAPs were examined at 5 Hz (n = 190), 10 Hz (n = 210), and 20 Hz (n = 185) steady stimulation. There was a progressive linear prolongation of latencies, as the stimulus rate increased (F = 95.6, p < 0.001); the least square means (SEM) of latency change were 100.7 (0.28)% at 5 Hz, 102.3 (0.27)% at 10 Hz and 105.3 (0.28)% at 20 Hz. There were statistically significant differences between frequencies by Tukey–Kramer’s method. Despite the significant latency prolongation, no activity-dependent conduction block developed. A 20 Hz electric stimulation to intramuscular axons was well-tolerated in all the subjects.

Conclusions

Tetanic stimulation at a constant rate results in significant latency increase in single human motor axons, the extent of which depends on the stimulus frequency. The findings imply that physiological discharge rates will activate the Na⁺/K⁺ pump and thereby produce axonal hyperpolarization in single motor axons.

Significance

This technique may detect activity-dependent conduction block if the safety margin of impulse transmission is significantly reduced by demyelination or increased branching due to collateral sprouting in a variety of neuromuscular disorders.     

Short-term stability of single motor unit recordings in motor neuron disease: a macro EMG study.

Thirty five individual macro EMG motor unit potentials in 13 patients with motor neuron disease were recorded every 15 minutes during a 2 hour period. No significant change in amplitude or area was seen in 15 control units in nine patients or in 20 units in 11 patients receiving RX77368 0.2-0.3 mg/kg. The findings provide no evidence for an action of this long acting TRH analogue on the peripheral territory of motor units in motor neuron disease.     

British motor neuron disease twin study.

OBJECTIVES: To investigate the cause of sporadic motor neuron disease (MND) by twin study, so allowing (1) estimation of the genetic contribution, and (2) collection of matched pairs for a case-control study of possible environmental factors. METHODS: 10872 death certificates bearing the diagnosis MND were collected from 1979 to 1989 inclusive. Inspection of individual birth entries allowed identification of potential twins. The status of each co-twin was determined and contact made through the National Health Service Central Register (NHS-CR) and their general practitioner (GP). The diagnosis of MND was verified via the co-twin and relatives, and medical records where available. Zygosity was assessed using a recognised questionnaire. Details concerning environmental exposures and health were gathered by interview of cotwin and relatives using a semistructured questionnaire. Heritability (h2) of MND was estimated, and the environmental information was analysed by conditional logistic regression modelling. RESULTS: Seventy seven probands were identified, of whom 26 were monozygotic and 51 dizygotic. Four monozygotic probands were concordant, but two probands came from a family known to have familial MND. The estimated heritability was between 0.38 and 0.85. Most environmental risk factors were not significant. Regular vehicle maintenance (odds ratio (OR) = 7.0; 95% confidence interval (95% CI) 1.3-89.9) and occupational paint usage (OR = 3.75; 95% CI 1.0-17.1), however, occurred significantly more often in the affected cases. CONCLUSIONS: This "death discordant" method for twin collection has proved to be viable, and has allowed the ascertainment of a large population sample in a rare disease. The genetic role in sporadic MND is substantial, and higher than expected. Exposure to industrial chemicals, particularly constituents of petrochemicals and paints, may contribute to the aetiology of MND.     

Voluntary activation and fiber density of fasciculations in motor neuron disease.

Two hundred voluntarily activated motor units and 211 fasciculations were recorded in the biceps of 10 patients with motor neuron disease with the Macro EMG technique. Twenty-two fasciculations, in nine of 10 muscles, had a potential of closely similar shape, amplitude, and area to that of a voluntary unit. Fasciculating units that could not be activated voluntarily had a higher mean number of spikes in their triggering single fiber potentials than units that could only be activated voluntarily, but statistically similar Macro EMG parameters. The mean number of single fiber spikes, and Macro EMG parameters, of fasciculations activated voluntarily, were similar to those of units that were only activated voluntarily. A positive correlation between fiber density and Macro EMG median amplitude and area in individual patients, and between number of single fiber spikes and Macro EMG amplitudes and areas in the pooled data, was found for fasciculations but not for voluntary units. At least 10% of fasciculations in patients with motor neuron disease may originate near or above the point of axonal branching and a proportion of those without evidence of voluntary activation may have a higher number of smaller muscle fibers, or more closely packed muscle fibers, of similar or greater size, than voluntarily activated motor units. Differences in the peripheral microanatomy of a number of fasciculation units not activated voluntarily may underlie ectopic impulse generation in the terminal axonal arborization, endplate zone, or muscle fibers of these units.     

Conduction velocity and refractory period of single motor nerve fibres in motor neuron disease.

Electromyographic single motor unit recordings were used to study the axonal conduction velocity and the axonal refractory period of 60 motor units in patients with severe motor neuron disease. Eighteen per cent of the motor units had abnormally low axonal conduction velocity probably due to secondary degenerative changes. Thirty-two per cent of the motor units had abnormally long axonal refractory period but normal conduction velocity. Whether this reflects a primary disease mechanism or secondary changes remains to be established.     

Double-blind study of modified neurotoxin in motor neuron disease.

In a double-blind study, we evaluated the intramuscular administration of modified neurotoxin in 48 patients who were treated for 6 months. There was no evidence to support claims that patients receive any benefit from the neurotoxin. A significant number of patients had minor functional improvement, often of a transient nature, but these manifestations were more common in the placebo-treated patients than in those receiving neurotoxin. These variations in the course of motor neuron disease have not been stressed in the previous literature.     

Ocular motor function in motor neuron disease.

We studied ocular motor function in 34 patients with motor neuron disease (MND) and in 18 age-matched controls. This included the latency, accuracy, and amplitude-velocity relationships of saccades. We also examined ocular pursuit, the slow phases of optokinetic nystagmus, and the ability to suppress the vestibulo-ocular reflex (VOR) with visual fixation of a head-mounted target. Five of the subjects with MND had pronounced parkinsonian features on neurologic examination. The nonparkinsonian MND subjects had normal ocular motor function for all measures. Most subjects suppressed the VOR completely. The parkinsonian-MND patients had impairment of both saccadic and pursuit eye movements, and one parkinsonian-MND patient with poor pursuit was unable to suppress the VOR. We conclude that ocular motor function is generally spared in MND. The occasional appearance of ocular motor dysfunction probably reflects the incidence of secondary abnormalities such as parkinsonism.