Rigid spine syndrome (vacuolar variant). A quantitative electromyograhic study

BACKGROUND: Quantitative electromyography (EMG) using different needle techniques was performed as part of a complete systems review on 9 patients diagnosed with the vacuolar variant of rigid spine syndrome (RSS). Purpose: To establish statistically: (1) correlations between clinical features (patient age, disease duration, degree of weakness) and quantitative EMG; (2) correlation between different EMG parameters; (3) differences in quantitative EMG comparing patients with a healthy control group; and (4) correlate EMG with muscle pathology findings. METHODS: Nerve conduction studies and needle EMG (motorunit analysis, MacroEMG, SFEMG) were performed on Mm. triceps brachii and tibialis anterior according to standard techniques on 9 RSS patients. RESULTS: Nerve conduction studies were normal. Overall, clinical parameters did not correlate well with motorunit analysis and MacroEMG results. Motorunit analysis and MacroEMG results were significantly different comparing patients with controls. Motorunit analysis and MacroEMG correlated well with muscle biopsy findings. SFEMG results were within normal limits. CONCLUSION: Comprehensive EMG study results were compatible with a benign myopathic process. Results were consistent amongst patients within the study group, but differed significantly from the control group. Stable neuromuscular junction physiology did not accurately reflect evidence of muscle fiber degeneration and regeneration observed on muscle biopsies.     

甲状腺机能亢进伴发重症肌无力患者电生理研究

目的：探讨甲状腺机能亢进（甲亢）伴发重症肌无力（MG）患者的电生理检测特点，和与慢性甲状腺机能亢进性肌病（CTM）的关系。方法：对7例甲亢伴发MG患者进行神经传导速度（NCV）、重复电刺激（RNS）、针极肌电图（EMG）和单纤维肌电图（SFEMG）检测。结果：7例NCV均正常，RNS5例异常。EMG2例发现有肌病的表现，SFEMG均出现jitter增宽。结论：甲亢病人可伴发MG，还可能同时伴发CTM，进行RNS、EMG、SFEMG检测是有必要的。     

甲状腺机能亢进性肌病的临床和肌电图研究

目的：探讨肌电图在甲状腺机能亢进(甲亢性肌病)性肌病中的临床应用价值及其与甲状腺素、病程和性别的关系。方法：对38例甲状腺功能亢进患者进行神经传导速度测定及肌电图检查。结果：38例甲亢患者运动神经及感觉神经传导速度正常，9例肌力减退者运动单位电位(MUP)时限缩短，29例肌力正常者中，MUP时限缩短者16例。男性患者MUP时限缩短的发生率高于女性，T3、T4增高者MUP时限缩短的发生率高于T3、T4正常者。病程短于4个月者MUP时限缩短的发生率较高。结论：EMG检测可发现亚I临床甲亢性肌病，MUP时限为较敏感和客观的指标，并与性别、甲状腺素水平及病程有关。     

Muscle fiber conduction velocity studied by the multi-channel surface EMG.

Muscle fiber conduction velocity in single motor unit (MU) during voluntary contraction was measured by using the multi-channel surface EMG. The subjects examined were 28 normal controls (5-40 years old), four patients with myopathy and three patients with neuropathy. The tibialis anterior and the biceps brachii muscles were investigated at weak and moderate contraction levels. In normal muscles, the mean muscle fiber conduction velocity increased with muscle force (P less than 0.01). In three of four cases with myopathy, the conduction velocities were reduced compared to normal subjects (P less than 0.01), and there was little or no correlation between the conduction velocity and muscle force in myopathy. The conduction velocities were within the normal range in the muscles of patients with neuropathy. However, high-amplitude MUAPs with fast conduction velocities were detected during weak voluntary contraction in one case with neuropathy.     

Fiber density in congenital muscle fiber type disproportion. II. Congenital muscle hypotonia and hip dislocation

Our previous paper presenting electromyographic findings in patients with congenital fiber type disproportion myopathy, confirmed the myogenic character of the disease process. That group of patients was however fairly heterogenous regarding both the clinical features and the morphological changes in muscle fibers (e.g. cases with central cores). In the present study we have examined 13 children with hypotonia and muscle fiber type disproportion operated on in childhood for congenital hip dislocation. In all cases CNEMG and SFEMG with FD estimation was performed in biceps brachii and quadriceps femoris muscles. In all muscles examined either slight EMG changes indicative of myopathy or a normal EMG pattern was found. None of the patients demonstrated an evident increase in FD values. Normal FD and the recruitment pattern proportional to the force of contractures indicate that the normal number of motoneurons is preserved. Accordingly, our present findings confirm the conclusions of our previous paper.     

The effect of motor learning in facioscapulohumeral muscular dystrophy patients

Two models of motor learning (ML) practice (complex and simple) were used to investigate upper limb function in individuals with facioscapulohumeral dystrophy (FSHD). The effect of ML practice was studied by examining changes in the ability to undertake a simulated drinking task. In the complex model, seven FSHD patients and seven age- and gender-matched healthy volunteers were studied. Performance was assessed by measurement of the electromyographic (EMG) activity of the biceps brachii and brachioradialis, elbow joint flexion, shoulder joint flexion and abduction, maximum acceleration at the onset of movement, movement time and reaction time, both before and after a 30-min complex ML task. In the simple model, a second group of six FSHD patients and six age- and gender-matched healthy subjects were studied. The same parameters were measured as for the complex ML task, except that the EMG activity of the triceps and deltoid muscles (anterior part) were measured instead of that of the brachioradialis. In both studies, the FSHD patients showed significantly larger values for all parameters except the flexion of shoulder joint and reaction time, compared with controls before the ML task. In the FSHD group, while the complex ML resulted in decreases in the brachioradialis EMG activity (P < 0.005) and reaction time (P < 0.0001), the simple ML model resulted in significant changes towards the normal value in all parameters measured except shoulder flexion. The change in the measured variables towards normal values indicates that ML may help to improve performance in FSHD. Accepted: 11 July 2000     

Afferent projections to human tibialis anterior motor units active at various levels of muscle contraction

The synaptic efficacy of muscle and cutaneous afferents on single tibialis anterior motoneurones in man was derived from changes in the firing probability of single, voluntarily activated, motor units in response to electrical stimulation of peripheral nerves or skin. The motor units were recorded with a Macro EMG electrode. The Macro motor unit potential (Macro MUP) recorded with this electrode reflects the electrical activity of all of the muscle fibres in a single motor unit. The amplitude of the Macro MUP is positively correlated with the recruitment threshold of the unit. Motor units with different Macro MUP amplitudes were examined at approximately the same level of voluntary contraction (less than 20% of maximum). The synaptic efficacy of muscle and cutaneous afferents was similar for units with small and with large Macro MUP amplitudes. Single motor units were examined at several different levels of muscle contraction. There was no consistent change in the facilitation from muscle afferents but there was less facilitation from cutaneous afferents during stronger contractions. This was not simply a consequence of the units faster firing rate. It is concluded that, with increasing voluntary drive to tibialis anterior motoneurones in man, there is a reduction in transmission in the pathways from cutaneous afferents to tibialis anterior motoneurones. There is no evidence that low and high threshold units (judging from their Macro MUP amplitudes) have different afferent connections.     

Physiological changes underlying bilateral isometric arm voluntary contractions in healthy humans

Many bilateral motor tasks engage simultaneous activation of distal and proximal arm muscles, but little is known about their physiological interactions. Here, we used transcranial magnetic stimulation to examine motor-evoked potentials (MEPs), interhemispheric inhibition at a conditioning-test interval of 10 (IHI(10)) and 40 ms (IHI(40)), and short-interval intracortical inhibition (SICI) in the left first dorsal interosseous (FDI) muscle during isometric index finger abduction. The right side remained at rest or performed isometric voluntary contraction with the FDI, biceps or triceps brachii, or the tibialis anterior. Left FDI MEPs were suppressed to a similar extent during contraction of the right FDI and biceps and triceps brachii but remained unchanged during contraction of the right tibialis anterior. IHI(10) and IHI(40) were decreased during contraction of the right biceps and triceps brachii compared with contraction of the right FDI. SICI was increased during activation of the right biceps and triceps brachii and decreased during activation of the right FDI. The present results indicate that an isometric voluntary contraction with either a distal or a proximal arm muscle, but not a foot dorsiflexor, decreases corticospinal output in a contralateral active finger muscle. Transcallosal inhibitory effects were strong during bilateral activation of distal hand muscles and weak during simultaneous activation of a distal and a proximal arm muscle, whereas GABAergic intracortical activity was modulated in the opposite manner. These findings suggest that in intact humans crossed interactions at the level of the motor cortex involved different physiological mechanisms when bilateral distal hand muscles are active and when a distal and a proximal arm muscle are simultaneously active.     

神经电生理对臀部肌注致坐骨神经损伤的诊断价值

目的：探讨神经电生理检测对臀部肌注致坐骨神经损伤的诊断意义。方法：对34例患者进行腓总神经、胫神经的神经传导速度（NCV）检测，并对胫骨前肌、腓肠肌、股二头肌长短头、椎旁肌L4-S1进行针极肌电图检测。结果：34例病例中，腓总神经传导速度NCV异常29例（85．3％），胫神经13例（38．2％），腓总神经、胫神经同时异常8例（23．5％）。经统计学处理，与正常对照组比较差异有显著意义（P〈0．01）。肌电图示，有失神经电位改变者：胫前肌为29例（85．3％），股二头肌短头为29例（85．3％），腓肠肌为13例（38．2％），股二头肌长头为13例（38．2％）。结论：神经电生理检测对臀部肌注致坐骨神经损伤的诊断可提供客观依据。     

Comparative and reliability studies of neuromechanical leg muscle performances of volleyball athletes in different divisions

This study compared neural profiles of the leg muscles of volleyball athletes playing in different divisions of Taiwan’s national league to analyse the reliability and correlations between their profiles and biomechanical performances. Twenty-nine athletes including 12 and 17 from the first and second divisions of the league, respectively, were recruited. The outcome measures were compared between the divisions, including soleus H-reflex, first volitional (V) wave, normalised rate of electromyography (EMG) rise (RER) in the triceps surae muscles, and RER ratio for the tibialis anterior and soleus muscles, normalised root mean square (RMS) EMG in the triceps surae muscles, antagonist co-activation of the tibialis anterior muscle, rate of force development (RFD), and maximal plantar flexion torque and jump height. Compared to the results of the second division, the neural profiles of the first division showed greater normalised V waves, normalised RER in the lateral gastrocnemius, and normalised RMS EMG of the soleus and lateral gastrocnemius muscles with less antagonist co-activation of the tibialis anterior. First division volleyball athletes showed greater maximal torque, jump height, absolute RFD at 0–30, 0–100, and 0–200 ms, and less in the normalised RFD at 0–200 ms of plantar flexion when compared to the results of those in the second division. Neural profiles correlated to fast or maximal muscle strength or jump height. There are differences in the descending neural drive and activation strategies in leg muscles during contractions between volleyball athletes competing at different levels. These measures are reliable and correlate to biomechanical performances.     

80例多发性肌炎、皮肌炎患者的肌电图研究

目的：探讨肌电图(EMG)、神经传导速度(NCV)的检测对提高多发性肌炎、皮肌炎的诊断价值。方法：分析80例多发性肌炎、皮肌炎患者肌电图检查中自发电活动,MUP时限、波幅及多相波,最大随意收缩时的募集形式,以及NCV检查及肌肉活检资料。结果：80例患者中65例EMG示肌原性损害,同时观察到15例患者出现NCV的轻度减慢(18．6%)、5例(6．3%)患者NCV远端潜伏期延长、21例(26．3%)患者出现复合肌动作电位波幅轻度下降。10例(12．5%)患者EMG、生化检查、肌肉活检正常,仅表现为MUP多相波增多,但追踪观察三个月后,其中6例患者EMG出现肌原性损害。结论：EMG、NCV测定和追踪监测是诊断多发性肌炎和皮肌炎的有价值的电生理检测方法。     

Electrophysiological recording of tendon reflexes in cervical myelopathy

Twenty-six patients with unequivocal, clinically and radiologically confirmed cervical myelopathy were investigated electrophysiogically using needle electromyography (EMG), motor and sensory conduction velocity, F-wave latency and the electromyographic recording of the tendon reflexes (TR) of the biceps brachii, brachioradialis and triceps brachii muscles. Normal latency and amplitude values of the reflex evoked compound muscle potentials (T-wave) were calculated from 74 healthy volunteers. Pathological TR were found in 73.1% of the patients, while EMG--which was the next more effective method--was positive in 38.5% of the cases. Eight pathologically delayed T-waves were recorded from muscles with clinically normal or even exaggerated reflexes. TR recording appears to be a useful method in the assessment of segmental functional disturbance in cervical myelopathy.     

多发性肌炎和皮肌炎患者的临床与肌电图分析

目的 :探讨多发性肌炎 (PM)和皮肌炎 (DM)病人的临床与肌电图特征。方法 :对 74例PM和DM临床与肌电图特征进行分析。结果 :首发症状以肌肉无力为最多见 (占 3 4% ) ,其他依次为皮肤损害 (占 3 1% ) ,发热 (占 13 % )。肌电图检查示肌原性损害 64例 ,神经原性损害 2例 ,异常率为 89%。主要表现为插入电位延长 (9% )、出现自发电位 (5 2 % ) ;MUP时限缩短 (74% )、MUP波幅降低 (6% ) ,多相波增多 (3 4% ) ;重收缩时波型异常 (4 5 % )及峰值波幅降低 (3 7% )。股四头肌、胫前肌及肱二头肌组阳性率显著高于外展拇短肌组 (P <0 0 5 ) ,胫前肌组MUP时限缩短阳性率最高 ,多相波增多阳性率胫前肌组最高。结论 :肌电图检查是诊断PM和DM的重要手段 ,选择股四头肌、胫前肌及肱二头肌进行EMG检查阳性率最高     

A comparative study of single fiber electromyography and repetitive nerve stimulation in consecutive patients with myasthenia gravis

AIM: To compare the diagnostic yield of single fiber electromyography (SFEMG) and repetitive nerve stimulation (RNS) in consecutive patients with myasthenia gravis (MG). METHODS: Consecutive 33 patients with MG diagnosed on the basis of clinical features, positive neostigmine test and/or acetylcholine receptor antibody assay were categorized into stage 1 (3), 2A (10), 2B (12) and 2C (8 patients). Low rate repetitive nerve stimulation (3Hz) was performed in distal muscles (abductor digiti minimi, anconeus, flexor carpi ulnaris, tibialis anterior) and proximal muscles (deltoid, serratus anterior, trapezius and nasalis). Decrement exceeding 10% was considered abnormal. Single fiber EMG was performed in extensor digitorum communis (EDC), recording 20 potential pairs. The abnormality was defined as mean jitter exceeding 40 micros or 10% of potential pairs having block or jitter exceeding 54 micros. The abnormality in RNS and SFEMG was compared and correlated with severity of MG. RESULTS: RNS study was carried out in 33 and SFEMG in 30 patients. In 2 patients SFEMG was not possible due to lack of cooperation and in one due to severe weakness. The RNS study was normal in 6 (2 in stage 1, 3 in 2A and 1 in 2B) patients and in all of them SFEMG was abnormal. The abnormality in RNS and SFEMG correlated with severity of MG. CONCLUSION: SFEMG is indicated in the patients with MG in whom RNS test is negative.     

Neural control: novel evaluation of stretch reflex sensitivity

We evaluated the stretch reflex activities of the elbow flexor and extensor muscles considering the relationship between the reflex electromyographic (EMG) responses and their corresponding standardized muscle stretch velocities. Specifically, muscular stretch velocity was estimated by using ultrasonograms. Stretch reflex EMG responses were elicited in the biceps brachii, brachioradialis and triceps brachii with a ramp-and-hold rotation at the elbow joint, which consisted of various angular velocities for the extension- or flexion-direction. The whole muscle stretch velocity induced by each ramp-and-hold rotation was calculated on the basis of fibre length changes associated with the elbow joint angle. A linear regression equation was fitted to the relation between the whole muscle stretch velocity and the reflex EMG responses, and the variables from the equation were used to quantify sensitivity of each reflex EMG component. The reflex EMG responses were increased as the ramp-and-hold rotational velocity increased. There were no significant differences in the recorded magnitudes of reflex EMG responses with equivalent joint rotational velocity between the brachioradialis and the triceps brachii medial head. These muscles showed the highest reflex responses in the flexor and extensor muscles, respectively. To the contrary, the reflex EMG response elicited by the standardized muscle stretches was significantly greater in the extensor muscles, indicating a higher reflex sensitivity. This was because of the lower muscle stretch velocity of the triceps brachii with an equivalent elbow joint rotation. The stretch reflex sensitivity in both the elbow flexor and extensor muscles might be regulated so as to make the reflex responses the same when the equivalent joint rotational velocity is applied to these muscles.     

Influence of neural adjustments and muscle oxygenation on task failure during sustained isometric contractions with elbow flexor muscles

This study investigated the adjustments in muscle activation and oxygenation in biceps and triceps brachii during two tasks sustained to failure at 20 and 60% of the maximal voluntary contraction (MVC) force. The tasks required participants either to push against a rigid restraint (force task) or to support an inertial load (position task) with the elbow flexor muscles. The surface EMG was recorded for biceps brachii, brachioradialis, triceps brachii and trapezius superior muscles. Muscle oxygenation of biceps and triceps brachii was measured by near-infrared spectroscopy. The position task was briefer (404 ± 159 s) than the force task (533 ± 194 s) when performed at 20% MVC (P = 0.011), but endurance time did not differ at 60% MVC (54 ± 19 versus 64 ± 16 s, respectively; P = 0.13). Biceps brachii oxygenation decreased slightly (by ~7%) during tasks performed at 20% MVC, whereas it dropped (-40%) for tasks sustained at 60% MVC. However, the decrease in muscle oxygenation was not a significant predictor of time to failure at the two target forces, although its contribution to muscle fatigue cannot be completely ruled out at 60% MVC. In contrast, time to failure was predicted by the increase in EMG of biceps brachii for both tasks at 20% MVC, and EMG of brachioradialis and trapezius for both tasks at 60% MVC. These results suggest that neural adjustments rather than muscle oxygenation limited the time to failure for the force and position tasks at low and high target forces.     

Shoulder and elbow muscle activity in goal-directed arm movements

 This research examined the electromyographic (EMG) activity of shoulder and elbow muscles during reaching movements of the upper limb. Subjects performed goal-directed arm movements in the horizontal plane. Movements which varied in amplitude, speed, and direction were performed in different sections of the workspace. EMG activity was recorded from the pectoralis major, posterior deltoid, biceps brachii short head, brachioradialis, triceps brachii long head, and triceps brachii lateral head; motion recordings were obtained with an optoelectric system. The analysis focused on the magnitude and timing of opposing muscle groups at the shoulder and elbow joints. For hand movements within any given direction of the workspace direction, kinematic manipulations changed agonist and antagonist EMG magnitude and intermuscle timing in a manner consistent with previous single-joint findings. To produce reaching movements in different directions and areas of the workspace, shoulder and elbow agonist EMG magnitude increased for those hand motions which required higher angular velocities, while the timing between opposing muscle groups at each joint was invariant. Received: 11 January 1996 / Accepted: 24 February 1997     

Evaluation of the ability to make non-invasive estimation of muscle contractile properties on the basis of the muscle belly response

The histochemical and biomechanical relationships of limb muscles are examined in two groups of 15 men aged between 17 and 40 years. Seven muscles are chosen: biceps brachii, triceps brachii (TB), flexor digitorum superficialis, extensor digitorum, biceps femoris, tibialis anterior and gastrocnemius caput mediale (GCM). The aim of the preliminary study is to evaluate an alternative method based on a tensiomyographic (TMG) non-invasive measurement technique. The percentage of type I muscle fibres obtained with the histochemical method is 2.2 times higher for the slowest measured muscle (GCM) than for the fastest (TB). The contraction time of a muscle belly twitch response measured by TMG is 1.9 times higher for GCM than for TB. Statistical analysis of the data obtained by tensiomyographic and histochemical techniques shows a significant correlation between the contraction time of muscle response measured by TMG and the percentage of type I muscle fibres (correlation coefficient equals 0.93). Results of the study suggest using the TMG measuring technique as a basis for the estimation of the percentage of type I muscle fibres.     

The effect of muscle pain on elbow flexion and coactivation tasks

The effects of muscle pain on movement can easily be observed in daily life routines. However, the influence of muscle pain on motor control strategies has not been fully clarified. In this human experimental study it was hypothesized that muscle pain affects the motor control of elbow flexion movements, in different combinations of range of motion and target size, by decreased agonistic muscle activity and increased antagonistic muscle activity with consequent implications on kinematic parameters. The effects of experimentally induced muscle pain on movement strategy for: (1) small and large range of motion (ROM) elbow flexion movements towards a wide target, (2) large ROM flexion movements towards a narrow and wide target, and (3) subsequent coactivation of agonistic and antagonistic muscles to elbow flexion were assessed. Muscle pain induced by injections of hypertonic saline (1 ml, 5.8%) in either m. biceps brachii or m. triceps brachii caused similar effects on the movements. For low accurate movements the initial (100 ms) integrated electromyographic (EMG) activity of m. biceps brachii was decreased during muscle pain. In contrast, integrated EMG of the entire m. biceps brachii burst was decreased by muscle pain only for small ROM at a low accuracy, which also showed decreased EMG activity of m. triceps brachii and m. brachioradialis, together with increased activity of m. trapezius. Finally, high accurate movements and post-movement coactivation were generally not modulated by muscle pain. In summary, the present study shows that acute muscle pain can perturb the motor control strategy, which might be highly important in occupational settings where such a change may need compensatory actions from other muscles and thereby eventually contribute to the development of musculoskeletal pain problems.     

Modulation of slow and fast elbow extensor EMG tonic activity by stretch reflexes in man

Summary Reflex EMG responses to sudden passive flexion of the elbow were recorded from anconeus and triceps brachii in 5 human volunteers.While the subjects were required not to resist the flexion movement, they were required to maintain an extension torque of 3.5 or 7.0 Nm prior to its onset.Under these isotonic conditions, the latency and amplitude of the reflex activities from anconeus and triceps brachii did not differ significantly, in contrast to the findings of Le Bozec (1986) in actively relaxed subjects. The myotatic/postmyotatic EMG amplitude ratio did not provide a further quantitative way to distinguish between these muscles.The absence of a difference between the reflex activities of a slow (anconeus) and a fast (triceps brachii) muscle is interpreted as resulting from a strong drive of spindle activity on the whole extensor motoneuron pool, which outweights the differences in recruitment due to the differing relative amounts of type I and type II fibres in the two muscles. Differences like those described between finger and calf muscles by other authors are though to be due to the relative degree of corticalization of these muscles.All short and long latency responses of the muscles increased in magnitude and decreased in latency with increasing background EMG activity as well as with increasing initial length. The position and tonic activity dependency of these responses is explained in terms of alpha-gamma coactivation.