基于双谱分析表面肌电信号特征的提取与模式识别

背景：肌电信号在本质上是一种具有非平稳、非高斯特性的生理信号。目前基于高阶累积量的高阶谱技术广泛应用于非高斯、非平稳、非线性等问题。 目的：基于非高斯AR参数模型,将双谱分析和fisher线性判别分析方法相结合进行表面肌电信号特征提取。 方法：针对表面肌电信号特点,从信号高阶统计处理角度,基于“非高斯AR参数模型”进行双谱分析,提取有效特征,用fisher线性判别分析降维方法构造特征向量,然后利用支持向量机实现不同动作模式的准确分类。并与多种常用表面肌电信号特征的识别准确率进行对比研究。 结果与结论：利用多类支持向量机分类器对8种前臂动作进行分类,8种动作的平均识别率达到97.6%以上。通过比较发现,基于短数据的双谱特征在分类性能上优于AR模型系数、小波包系数等构造的特征,能够提高肌电假肢的实时控制的性能。     

表面肌电信号的分析和特征提取***☆◆

背景：表面肌电信号的检测与分析对临床诊断人体功能状况以及患者康复具有重要意义。 目的：对表面肌电信号的采集、信号处理、特征分析和特征值提取方面进行分析。 方法：在人体屈伸肘部的过程中,选取人体上肢4块肌肉(肱三头肌,肘肌,肱二头肌,肱桡肌)分别检测表面肌电信号,对表面肌电信号进行陷波和带通滤波等预处理(优化)。在此基础上分析表面肌电信号的特征,并应用不同的特征值提取方法对优化后的表面肌电信号进行了特征提取。 结果与结论：时域方法最早应用于肌电信号分析,易提取、方法简单;频域方法提取的特征值较稳定,使得频域方法成为肌电信号处理技术的主流;以小波变换为代表的时-频分析方法因结合了时域、频域两方法的特性,在肌电信号分析方面颇有潜力。 关键词：表面肌电信号;信号采集;信号处理(优化);特征分析;特征值提取。     

表面肌电信号对脑卒中患者远程居家康复指导的效果研究

目的探讨表面肌电信号对指导脑卒中患者居家远程康复的效果。方法筛选2014年7月至2015年6月在上海市第五人民医院神经内科住院治疗的脑卒中患者78例,78例患者通过SPSS统计软件按1:1的比例分成两组,分别为表面肌电信号指导进行居家康复的治疗组(39例)与无表面肌电信号指导居家康复的常规组(39例)。采用简化FuglMeyer运动功能量表(FMA)评定上肢功能,通过均方根值(RMS)测定肌肉收缩时的收缩强度。结果康复治疗前,两组患者上肢FMA评分与RMS评分比较,差异无统计学意义(P0.001)。康复治疗后,两组患者上肢FMA评分与RMS评分均较康复治疗前增加,差异具有统计学意义(P0.001)。康复治疗后,治疗组上肢FMA评分与RMS评分均较常规组增加,差异具有统计学意义(FMA:P=0.02;RMS:P=0.018)。结论康复过程中进行表面肌电信号调整康复方案可增强运动功能康复的效果。     

兔腓肠肌表面肌电信号与肌肉收缩及运动中枢的关系

背景：以往的验证实验均采用电刺激方法诱发肌肉收缩,施加电流的影响使接收到的表面肌电信号混有外来电流成分,无法有效分析其与肌肉收缩,特别是与高位运动中枢的关系。 目的：观察新西兰兔腓肠肌表面肌电信号与肌肉收缩及高位、低位运动中枢的关系。 方法：在新西兰兔清醒状态下通过针刺右侧跟腱诱发腓肠肌收缩,局麻清醒状态下离断右侧坐骨神经,分别在针刺跟腱、钳夹离断的坐骨神经远侧断端、针刺腓肠肌和被动活动腓肠肌时,检测腓肠肌表面肌电信号的强弱及类型。局麻下于L3平面横断脊髓,针刺左侧跟腱诱发腓肠肌收缩,检测腓肠肌表面肌电信号的强弱和类型。 结果与结论：正常状态下经针刺跟腱诱发腓肠肌随意收缩时,可接收到400 μV、持续4 s的宽底随意波;横断脊髓后针刺跟腱诱发的反射性腓肠肌收缩接收到的信号小于100 μV、持续时间小于1 s;离断坐骨神经后刺激跟腱、神经和肌肉时,均未引起肌肉收缩,但可接收到强度小于10 μV、持续时间小于0.5 s的干扰波;被动活动关节牵拉腓肠肌时未检测到肌电信号活动。说明兔腓肠肌表面肌电信号产生于肌肉收缩之前,是以高位运动中枢为主、低位运动中枢为辅发放到肌肉的驱动电信号的综合,而非肌肉收缩本身产生。     

基于Mu/Beta节律的想象运动脑电信号特征提取

背景：不同的运动会产生不同的脑电信号,脑机接口技术就是利用脑电信号的特异性,通过现代信号处理技术和外部的连接实现人脑与外部设备的通信。以实现脑机接口在线研究的目标,首先要解决的是脑电信号处理的速度问题。 目的：研究快速、准确地提取脑电信号特征及分类的方法。 方法：充分利用想象运动过程中,脑电信号中Mu/Beta节律的事件相关同步化和去同步化特性,以2003年BCI竞赛数据为处理对象,采用带通滤波和小波包分析的方法提取Mu、Beta节律,提取C3、C4两通道上的能量平均值形成二维特征向量,利用matlab自带的classify函数进行分类。 结果与结论：通过对训练数据进行测试得到较为合适的参数,利用该参数对同等条件下的训练数据和测试数据分别进行判别,分类正确率分别达到87.857%和88.571%。 关键词：特征提取与分类;脑电信号;事件相关同步化/去同步化;想象运动;小波包分析     

女性盆底肛提肌的有限元分析*

背景：有限元分析法在骨科生物力学研究领域中已得到广泛的应用,作为与传统实验生物力学互相验证和互为补充的方法,它发挥着其他方法不可替代的作用。目前有限元分析法对人体软组织(如肛提肌)的研究在国内外尚处于初级阶段,但其发展极其迅速。目的：针对女性盆底肛提肌的有限元分析研究进展作一综述。方法：由第一作者检索1990/2008 PubMed数据及中国期刊引文数据库中有关盆底功能障碍性疾病与盆底肛提肌有限元及生物力学分析与盆底重建等方面的文献。 结果与结论：通过对女性盆底肛提肌有限元模型的建立及其分析不仅有助于了解盆底功能障碍性疾病的发生机制,而且还能帮助改进医疗器械设计及实施最佳外科手术计划。虽然现在对盆底软组织肌肉的有限元模型建立及分析尚处于初级阶段,但随着计算机硬件的飞速发展及各类有限元应用软件的持续改进,有限元法的应用将越加广泛。关键词：盆底肛提肌;有限元法;女性;盆底软组织;数字化医学     

Measurement of tendon reflexes by surface electromyography in normal subjects

Summary A simple method for measuring the tendon reflexes was developed. A manually operated, electronic reflex hammer was applied that enabled measurement of the strength of tendon taps. Reflex responses were recorded by surface electromyography. Stimulus-response relations and latencies of tendon reflexes in the biceps, triceps, quadriceps and triceps surae were examined in 40 healthy subjects. A characteristic relation between stimulus strength and response amplitude was found which could be described by an empirical function. Latencies of both arm and leg reflexes were linearly related to the height of the subjects. Variations of reflex amplitudes within and between subjects were comparable with previous results obtained with more complicated techniques. Although repeatability of measurement of the amplitude is limited by the variability of reflexes, significant agreement was found between repeated measurements. Most reflex amplitudes were diminished during repeated examination after a short interval. Both measurement and clinical examination showed the frequent occurrence of left-right asymmetry of reflex amplitudes. These left-right differences were reproducible to a significant degree on repeated measurements after more than 2 years.     

斜方肌肌电图运动单位动作电位成人正常参考值的建立

目的 探讨不同血清抗体重症肌无力(MG)的临床特征.方法 用荧光免疫沉淀法(FIPA)和荧光免疫细胞染色法(CBA)检测119例MG患者血清乙酰胆碱受体抗体(AChR-Ab)和肌肉特异性受体酪氨酸激酶抗体(MuSK-Ab)水平.比较AChR-Ab阳性、MuSK-Ab阳性、血清抗体阴性MG的临床特征.结果 纳入119例患者中,90例AChR-Ab阳性(75.6%),29例阴性:其中5例MuSK-Ab阳性(17.2%),24例血清抗体阴性(82.8%).AChR-Ab阳性、MuSK-Ab阳性和血清抗体阴性MG 3组比较,男女比例和平均发病年龄差异均无统计学意义.3例MuSK-Ab阳性的患者主要表现为延髓肌受累;79.2%(19/24)的血清抗体阴性MG患者表现为美国MG协会(MGFA)Ⅰ型;2例MuSK-Ab阳性的患者MGFA≥Ⅲ型;MuSK-Ab滴度水平与患者病情严重程度相关(r=0.941,P=0.014);MuSK-Ab阳性的患者均未发现有胸腺的异常.结论 MuSK-Ab仅出现在AChR-Ab阴性患者的血清中.MuSK-Ab阳性的患者主要表现为延髓肌受累,病情较重且不伴有胸腺的病变.MuSK-Ab阳性的MG可能是不同于血清AChR-Ab阳性的MG的又一亚型.     

Detection of convulsive seizures using surface electromyography

Bilateral (generalized) tonic–clonic seizures (TCS) increase the risk of sudden unexpected death in epilepsy (SUDEP), especially when patients are unattended. In sleep, TCS often remain unnoticed, which can result in suboptimal treatment decisions. There is a need for automated detection of these major epileptic seizures, using wearable devices. Quantitative surface electromyography (EMG) changes are specific for TCS and characterized by a dynamic evolution of low‐ and high‐frequency signal components. Algorithms targeting increase in high‐frequency EMG signals constitute biomarkers of TCS; they can be used both for seizure detection and for differentiating TCS from convulsive nonepileptic seizures. Two large‐scale, blinded, prospective studies demonstrated the accuracy of wearable EMG devices for detecting TCS with high sensitivity (76%‐100%). The rate of false alarms (0.7‐2.5/24 h) needs further improvement. This article summarizes the pathophysiology of muscle activation during convulsive seizures and reviews the published evidence on the accuracy of EMG‐based seizure detection.     

Use of the surface EMG signal for performance evaluation of back muscles

For well over a decade my associates and I have been developing an objective, noninvasive technique to evaluate the performance of low-back muscles, with emphasis on being able to distinguish between healthy and dysfunctioned backs. Our approach is based on the well-known fact that the EMG signal undergoes a compression in the frequency domain during a sustained muscle contraction. In particular we track the median frequency of EMG signals detected from six muscles in the lower back during an isometric extension of the trunk. The measurements are taken with the Back Analysis System which consists of a postural restraining device, special electrodes for detecting the EMG signals, a muscle fatigue monitor which calculates the median frequencies, and the appropriate software. We have found that the pattern of fatigue exhibited by the six median frequency curves can be used to distinguish individuals who have low-back pain from those who do not with an accuracy of at least 84%. An even more relevant and timely application of our technique is for quantifying the progression of the performance of low-back muscles during a rehabilitation program. Although more work is required to explore the intricacies of the technique, present results provide a convincing indication that it is reliable and that it is ready to be placed into practice. © 1993 John Wiley & Sons, Inc.     

Prediction of time-to-exhaustion in the first dorsal interosseous muscle from early changes in surface electromyography parameters

Introduction: In this study we evaluated the precision of the time‐to‐exhaustion (T_lim) prediction from the early changes in surface electromyography (sEMG) of the first dorsal interosseous muscle. Methods: Thirty subjects performed an index finger isometric abduction at 35% of maximal voluntary contraction (MVC) until exhaustion. Ten participants performed the same exercise at 50% MVC 1 week later. Changes in sEMG parameters across time were modeled using the area‐ratio and the linear regression slope. T_lim was plotted as a function of each of these indices of change, and the coefficient of determination (R²) was determined. Results: Null to moderate R² (0.22 and 0.56 at 35% and 50% MVC, respectively) values were calculated. The best T_lim estimation led to a high prediction error (21.6 ± 15.0% of T_lim for the 50% MVC task). Conclusions: Although the prediction of time‐to‐exhaustion is an appealing research topic, these results suggest that it cannot be done solely from sEMG. Muscle Nerve 45: 835–840, 2012     

肛门括约肌肌电图对多系统萎缩Onuf核损伤的判断

目的分析多系统萎缩的肛门括约肌肌电图特点,探讨其在多系统萎缩Onuf核损伤判断中的价值。方法多系统萎缩患者68例和肌萎缩侧索硬化15例,分别行肛门括约肌肌电图检查,观察静息时有无自发电位;轻收缩(自然状态)时运动单位电位的平均时限、平均波幅、多相波百分比、有无卫星电位;大力收缩(缩肛)时的相型和波幅。对两组各参数进行统计分析。结果多系统萎缩患者组65例(95.6%)肛门括约肌肌电图有不同程度的改变,肌萎缩侧索硬化组未发现异常变化。运动单位电位的平均时限、平均波幅、多相波百分比、自发电位两组比较有显著性差异(P<0.001,P<0.01,P<0.001)。结论多系统萎缩肛门括约肌肌电图的改变,能反映多系统萎缩的Onuf核选择性的弥漫性细胞脱失的特性。在怀疑多系统萎缩Onuf核损伤时,该项检查对损伤的判断有较大价值。     

Detection radius of EMG for fasciculations: Empiric study combining ultrasonography and electromyography

Objective

The aims of this study were to investigate the detection radius and sensitivity of EMG for fasciculations.