腓骨肌萎缩症患者的临床与神经电生理特征分析

目的:探讨腓骨肌萎缩症(Charcot-Marie-Tooth disease,CMT)的临床与神经电生理特征;方法:应用肌电图仪检测和分析21例腓骨肌萎缩症患者的电生理特征,包括肌电图和运动、感觉神经传导速度;分析电生理特征与临床之间的关系;结果:16例患者肌电图出现纤颤电位和(或)正锐波,17例患者运动单位(MUP)时限延长。11例腓总神经、13例胫神经运动传导速度(MCV)未引出,1例正中神经、2例尺神经MCV未引出,3例正中神经、2例尺神经MCV正常,其余均有不同程度减慢;15例腓肠神经感觉神经传导速度(SCV)未引出,3例正中神经、6例尺神经SCV未引出,7例正中神经、5例尺神经SCV正常,其余均有不同程度减慢。结论:CMT患者的神经电生理特征大多数呈神经原性损害,运动和感觉神经传导速度有不同程度的受累,下肢的神经病变重于上肢,临床表现结合神经肌电图检查有助于CMT的确诊。     

Attenuation of human neck muscle activity following repeated imposed trunk-forward linear acceleration

It has been suggested that, after a passive linear acceleration of a seated subject which resembles a small, rear-end car impact, sensory information from proprioceptive, vestibular, and visual systems elicit stabilizing neck muscular responses. These neck muscular responses are presumably reflex based and are modified with the magnitude of the perturbation. A key issue that remains is to determine whether the neck and head postural responses can be modulated by a previous experience of the acceleration and not only by the magnitude of the acceleration. This question is of interest because, contrary to cadaver studies, one could expect that humans apprehending a rapid trunk acceleration would adopt a bracing behavior to minimize head movements. The aim of the present experiment was to verify whether neck-muscle activities can be modulated when prior knowledge about whole-body acceleration onset, direction, and magnitude are unknown compared with when only acceleration onset is unknown. Nine seated subjects were submitted to 11 imposed, forward linear accelerations (1.1g). For the first trial, subjects were completely unaware of the platform acceleration characteristics (onset, direction, amplitude, and acceleration magnitude). For the subsequent ten trials, subjects knew they would be submitted to a forward linear acceleration, but the onset of the acceleration was unknown. Head kinematics and EMG responses of the neck muscles to the first perturbation were similar for all subjects (6.2° head extension, EMG activity starting from 55 to 72 ms after platform onset). Following the first trial, however, all subjects showed a decreased neck EMG activity. Moreover, subjects responded in one of two ways across trials: one group of subjects (n=5) maintained a constant head angular position and velocity, whereas the other group (n=4) showed an increased head angular position (up to 12.6°) and velocity. This suggests that the first perturbation trial revealed a completely reactive response. After this initial trial, the responses observed may present a mixture of feedforward and feedback control. It is likely that whiplash injuries occur under conditions resembling those observed for the first trial only. If this is the case, the behavior for the following trials cannot be representative of injury mechanisms occurring in whiplash-like motion. Altogether, our results strongly suggest that, following repeated trunk linear accelerations of a constant magnitude, the nervous system prefers to minimize muscle stress instead of adopting a bracing strategy. Electronic Publication     

Searching for a marker of REM sleep behavior disorder: submentalis muscle EMG amplitude analysis during sleep in patients with narcolepsy/cataplexy

STUDY OBJECTIVES: To evaluate the amplitude of submentalis muscle EMG activity during sleep in patients with narcolepsy/cataplexy with or without REM sleep behavior disorder (RBD). DESIGN: Observational study with consecutive recruitment. SETTINGS: Sleep laboratory. PATIENTS: Thirty-four patients with narcolepsy/cataplexy and 35 age-matched normal controls. MEASUREMENTS AND RESULTS: Half the patients (17 subjects) had a clinical and video polysomnographic diagnosis of RBD. The average amplitude of the rectified submentalis muscle EMG signal was used to assess muscle atonia, and the new REM sleep Atonia Index was computed. Chin muscle activations were detected and their duration and interval analyzed. REM sleep Atonia Index was lower in both patient groups (with narcolepsy patients with RBD showing the lowest values) with respect to controls, and it did not correlate with age as it did in controls. The total number of chin EMG activations was significantly higher in both patient groups than controls. No significant differences were found between the two groups of patients, although more chin EMG activations were noted in narcolepsy patients with RBD than those without. CONCLUSIONS: Elevated muscle activity during REM sleep is the only polysomnographic marker of RBD. This study shows that polysomnographically evident RBD is present in many patients with narcolepsy/ cataplexy. This condition might be specific to narcolepsy/cataplexy, reflecting a peculiar form of REM sleep related motor dyscontrol (i.e., status dissociatus), paving the way to enacting dream behaviors, and correlated with the specific neurochemical and neuropathological substrate of narcolepsy/cataplexy.     

A quantitative statistical analysis of the submentalis muscle EMG amplitude during sleep in normal controls and patients with REM sleep behavior disorder

The aim of this study was to evaluate quantitatively the amplitude of the submentalis muscle EMG activity during sleep in controls and in patients with idiopathic REM sleep behavior disorder (RBD) or with RBD and multiple system atrophy (MSA). We recruited 21 patients with idiopathic RBD, 10 with MSA, 10 age-matched and 24 young normal controls. The average amplitude of the rectified submentalis muscle EMG signal was used for the assessment of atonia and a Sleep Atonia Index was developed; moreover, also chin muscle activations were detected and their duration and interval analyzed. The Sleep Atonia Index was able to distinguish clearly REM from NREM sleep in normal controls with values very close to 1 in young normal subjects and only slightly (but significantly) lower in old controls. Idiopathic RBD patients showed a further significant decrease of this index; MSA patients showed the lowest values of REM Sleep Atonia Index, which were very well distinguishable from those of normal controls and of idiopathic RBD patients. The distribution of the duration of chin activations was monomodal in all groups, with idiopathic RBD patients showing the highest levels. This study is a really quantitative attempt to provide practical indices for the objective evaluation of EMG atonia during REM sleep and of EMG activations. Our proposed Sleep Atonia Index can have a practical application in the clinical evaluations of patients and represents an additional useful parameters to be used in conjunction with the other criteria for the diagnosis of this sleep motor disorder.     

Relative torque contribution of vastus medialis muscle at different knee angles

Aim: We investigated the relative contribution of the vastus medialis (VM) muscle to total isometric knee extension torque at 10°, 30°, 60° and 90° knee flexion. In the past a more prominent role of the VM muscle at more extended knee angles has been put forward. However, different components of the quadriceps muscle converge via a common distal tendon. We therefore hypothesized that the relative contribution of the VM to total knee extension torque would be similar across angles. Methods: At each knee angle the EMG isometric torque relations [20%, 25%, 30%, 35% maximal voluntary contraction (MVC)] of the rectus femoris (RF), vastus lateralis (VL) and VM muscle were established in 10 healthy male subjects; rectified surface EMG was normalized to M‐wave area. Subsequently, the VM was functionally eliminated by selective electrical surface stimulation with occluded blood flow. Results: There was no evidence for preferential activation of VM at any of the knee angles. Following VM elimination, total knee extension torque during maximal femoral nerve stimulation (three pulses at 300Hz) at 10°, 30°, 60° and 90°, respectively, decreased (P < 0.05) to (mean ± SD): 75.7 ± 12.2, 75.1 ± 9.3, 78.2 ± 7.2 and 76.0 ± 5.8% (P > 0.05 among knee angles). In addition, during voluntary contractions at 20% MVC the increases in torque output of RF and VL compensating for the loss of VM function were calculated from the increases in EMG and found to be similar (P > 0.05) at 10°, 30°, 60° and 90° values (%MVC), respectively, were: 9.1 ± 6.8, 7.5 ± 2.9, 5.9 ± 3.7 and 6.9 ± 3.4. Conclusion: The present findings support our hypothesis that the VM contributes similarly to total knee extension torque at different knee angles.     

Adaptive spatio-temporal filtering of multichannel surface EMG signals

A motor unit (MU) is defined as an anterior horn cell, its axon, and the muscle fibres innervated by the motor neuron. A surface electromyogram (EMG) is a superposition of many different MU action potentials (MUAPs) generated by active MUs. The objectives of this study were to introduce a new adaptive spatio-temporal filter, here called maximum kurtosis filter (MKF), and to compare it with existing filters, on its performance to detect a single MUAP train from multichannel surface EMG signals. The MKF adaptively chooses the filter coefficients by maximising the kurtosis of the output. The proposed method was compared with five commonly used spatial filters, the weighted low-pass differential filter (WLPD) and the marginal distribution of a continuous wavelet transform. The performance was evaluated using simulated EMG signals. In addition, results from a multichannel surface EMG measurement fro from a subject who had been previously exposed to radiation due to cancer were used to demonstrate an application of the method. With five time lags of the MKF, the sensitivity was 98.7% and the highest sensitivity of the traditional filters was 86.8%, which was obtained with the WLPD. The positive predictivities of these filters were 87.4 and 80.4%, respectively. Results from simulations showed that the proposed spatio-temporal filtration technique significantly improved performance as compared with existing filters, and the sensitivity and the positive predictivity increased with an increase in number of time lags in the filter.     

MUAP extraction and classification based on wavelet transform and ICA for EMG decomposition

We have developed an effective technique for extracting and classifying motor unit action potentials (MUAPs) for electromyography (EMG) signal decomposition. This technique is based on single-channel and short periodȁ9s real recordings from normal subjects and artificially generated recordings. This EMG signal decomposition technique has several distinctive characteristics compared with the former decomposition methods: (1) it bandpass filters the EMG signal through wavelet filter and utilizes threshold estimation calculated in wavelet transform for noise reduction in EMG signals to detect MUAPs before amplitude single threshold filtering; (2) it removes the power interference component from EMG recordings by combining independent component analysis (ICA) and wavelet filtering method together; (3) the similarity measure for MUAP clustering is based on the variance of the error normalized with the sum of RMS values for segments; (4) it finally uses ICA method to subtract all accurately classified MUAP spikes from original EMG signals. The technique of our EMG signal decomposition is fast and robust, which has been evaluated through synthetic EMG signals and real EMG signals.     

膝骨关节炎患者肌电标准化方法的信度研究

目的 评估标准等长收缩(standard isometric contraction, SIC)与最大随意等长收缩(maximum voluntary isometric contraction, MVIC)应用于膝骨关节炎(knee osteoarthritis, KOA)患者肌电标准化的重测信度。方法 采用无线肌电测试系统收集KOA患者患侧腿在慢跑、SIC测试和MVIC测试时臀大肌、半腱肌、股直肌、股外侧肌、胫骨前肌、外侧腓肠肌和比目鱼肌的肌电数据。使用组内相关系数和95%置信区间评估重测信度。结果 KOA患者执行SIC测试时7块肌肉的重测信度均较好,执行MVIC测试时5块肌肉重测信度一般,2块肌肉重测信度较好,7块肌肉在SIC测试中的重测信度均高于MVIC测试;KOA患者慢跑时7块肌肉经SIC标准化后的重测信度均高于经MVIC标准化的重测信度,且股直肌经SIC标准化后的重测信度显著高于经MVIC标准化的重测信度。结论 对于KOA患者,SIC是一种比MVIC更为可靠的表面肌电标准化方案,具有较好的临床推广潜力。     

Effect of contingent electrical stimulation on jaw muscle activity during sleep: A pilot study with a randomized controlled trial design

Abstract

Objective. To determine the effect of contingent electrical stimulation (CES) on jaw muscle activity during sleep in a double-blinded randomized controlled trial (RCT). Materials and methods. Eleven patients with myofascial TMD (mean age 37 years) and with a clinical diagnosis of bruxism were included. EMG activity (Grindcare®) was recorded from the anterior temporalis muscle during sleep and analyzed online. Jaw muscle activity related to clenching or grinding triggered an electrical square-wave pulse train (450 ms) adjusted to a clear, but non-painful intensity. TMD patients were randomized into two groups: active treatment with CES or no CES (placebo). Number of EMG episodes/hour sleep was the primary outcome parameter. The following variables were assessed as secondary outcome parameters; number of painful muscles, maximum pain-free jaw opening, characteristic pain intensity, depression scores and Oral Health Impact Profile scores. Numerical Rating Scale scores for self-reported pain and muscle tension were registered for at least 4 nights per week during the experiment. Results. The number of EMG episodes/hour sleep was significantly reduced (52 ± 12%) in the CES group during the sessions with CES (ANOVA: p = 0.021) compared to baseline. There were no significant differences in the secondary outcome parameters (ANOVA: p > 0.513) or pain or muscle tension scores between groups (p = 0.645). The average duration of sleep hours during the nights with and without CES was not significantly different (p = 0.646). Conclusions. These results demonstrate a significant inhibitory effect of CES on jaw muscle EMG activity during sleep in a RCT, but with no effects on self-reported pain.