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At least 1,153 records · Page 64Linked to original sources
PubMed1998

Electromyography of the diaphragm in neuromuscular disease.

We compared the diaphragmatic electromyographic (EMG) recordings from 32 patients with known neuromuscular disease and respiratory symptoms (23 neuropathies, 9 myopathies) to recordings from 23 normal subjects. Turns analysis of 219-ms sections, or epochs, of the EMG demonstrated a significant overlap between diagnostic groups, although some epochs from neuromuscular patients were significantly different from normal. Empirical rules were derived to infer neuropathic and myopathic involvement of the diaphragmatic EMG.

Diaphragm↗
PubMed1998

Sports and peripheral nerve injuries: report of 190 injuries evaluated in a single electromyography laboratory.

We retrospectively reviewed electrodiagnostic studies performed on 169 athletes with 190 sports injuries to nerve fibers. Eighty-eight percent of the injuries were to the upper extremity. Athletes participated in 27 sports, but over one third of injuries were sustained playing football. The most common injuries were burners (n = 38) and cervical radiculopathies (n = 18), followed by median (n = 28), axillary (n = 22), ulnar (n = 19), suprascapular (n = 14), and peroneal (n = 11) mononeuropathies. This is the largest reported series of sports-related nerve injuries.

Adolescent↗
PubMed2000

Standardization of anal sphincter electromyography: uniformity of the muscle.

The different parts of the external anal sphincter (EAS) are usually regarded as one muscle with common EMG characteristics. This assumption was addressed by comparing the number of continuously firing motor units (MUs) during relaxation, as well as the parameters of motor unit potentials (MUPs) and interference pattern (IP) in the subcutaneous and the deeper parts of EAS. MUPs and IPs were analyzed in 44 subjects (2008 MUPs and 3014 IPs) without uroneurological or proctological disorders, and the number of continuously active MUs in 34 of these subjects was recorded (221 positions). No significant difference was found in IP and most MUP parameters between the two parts of the EAS muscle, but the number of continuously firing MUs was lower in the deeper part. As far as MUP and IP characteristics are concerned, the whole EAS can be considered as one muscle, but some differences in patterns of activation of MUs may exist in different regions.

Adult↗
PubMed1998

Smooth muscle electromyography of the urinary bladder.

To elucidate smooth muscle activity of the urinary bladder, we utilized an optimized animal model and a specially developed, computer-aided data acquisition and analysis system for bioelectrical signals. Twenty-five Wistar rats were pharmacologically paralyzed and artificially respirated. The urinary bladder was exposed by a suprapubic midabdominal incision, and both ureters were ligated to prevent physiological filling of the bladder. The bladder was initially emptied by slight manual pressure and was then filled via a transurethral catheter in 0.1-ml steps to a maximum of 0.45 ml with physiological saline. A custom-made, gold-plated needle electrode was tangentially guided by a micromanipulator to the smooth muscle of the bladder dome, and the recordings commenced. Furthermore, smooth muscle EMG recordings of the bladder were performed after pharmaco-stimulation of the detrusor with carbachol. Initial results demonstrate that, with the animal model presented here, it is possible to record reproducible and almost artifact-free smooth muscle activity from the urinary bladder. All experiments displayed a stochastic distribution of similar electrical events, increasing in appearance and amplitude with increased bladder volume and after pharmacostimulation with carbachol. Two-dimensional power spectrum analysis revealed a main signal frequency below 1 Hz.

Animals↗
PubMed2000

Electromyography of the anterior temporalis and masseter muscles of owl monkeys (Aotus trivirgatus) and the function of the postorbital septum.

Anthropoids and tarsiers are distinguished from all other vertebrates by the possession of a postorbital septum, which is formed by the frontal, alisphenoid, and zygomatic bones. Cartmill [(1980) In: Evolutionary Biology of the New World Monkeys and Continental Drift. New York: Plenum, p 243-274] suggested that the postorbital septum evolved in the stem lineage of tarsiers and anthropoids to insulate the eye from movements arising in the temporal fossa. Ross [(1996) Am J Phys Anthropol 91:305-324] suggested that the septum insulates the orbital contents from incursions by the line of action of the anterior temporal muscles caused by the unique combination of high degrees of orbital frontation and convergence. Both of these hypotheses must explain why insulation of the orbital contents could not be achieved by decreasing the size of the anterior temporal musculature with a corresponding increase in size of the remaining jaw adductors, rather than evolving a postorbital septum. One possibility is that the anterior temporalis is an important contributor to vertically directed bite forces during all biting and chewing activities. Another possibility is that reduction in anterior temporal musculature would compromise the ability to produce powerful bite forces, either at the incisors or along the postcanine toothrow. To evaluate these hypotheses, electromyographic (EMG) recordings were made from the masseter muscle and the anterior and posterior portions of the temporalis muscles of two owl monkeys, Aotus trivirgatus. The EMG data indicate that anterior temporalis activity relative to that of the superficial masseter is lower during incision than mastication. In addition, activity of the anterior temporalis is not consistently higher than the posterior temporalis during incision. The data indicate relatively greater activity of anterior temporalis compared to other muscles during isometric biting on the postcanine toothrow. This may be due to decreased activity in superficial masseter and posterior temporalis, rather than elevated anterior temporalis activity. The anterior temporalis is not consistently less variable in activity than the superficial masseter and posterior temporalis. The EMG data gathered here indicate no reason for suggesting that the anterior temporal muscles in anthropoids are utilized especially for incisal preparation of hard fruits. Maintenance of relatively high EMG activity in anterior temporalis across a wide range of biting behaviors is to be expected in a vertically oriented and rostrally positioned muscle such as this because, compared to the posterior temporalis, superficial masseter and medial pterygoid, it can contribute relatively larger vertical components of force to bites along the postcanine toothrow. The in vivo data do not support this hypothesis, possibly because of effects of bite point and bite force orientation.

Animals↗
PubMed2000

Motor unit sound in needle electromyography: assessing normal and neuropathic units.

Motor unit action potentials (MUPs) recorded by a monopolar needle electrode in normal and neuropathic muscles were computer-simulated. Five experienced electromyographers acted as examiners and assessed the firing sounds of these MUPs without seeing them on a display monitor. They judged whether the sounds were crisp or close enough to accept for the evaluation of MUP parameters and whether, when judged acceptable, they were neuropathic-polyphasic. The examiners recognized motor unit (MU) sound as crisp or polyphasic when the MUP obtained was 0.15-0.2 mm from the edge of the MU territory. When the intensity of the sound decreased, they were unable to perceive it as crisp. When the intensity exceeded the saturation level of loudspeaker output, the sound was perceived as polyphasic, but the wave form of the MUP was not. When the frequency of the neuropathic MUP was lowered, the examiners were unable to determine whether the MUP was polyphasic. MUPs recognized as acceptable for evaluation can be distinguished by listening to MU sounds. The audio amplifier gain must be appropriately adjusted for each MUP amplitude in order to assess whether an individual MU sound is crisp or polyphasic before MUP parameters are measured on a display monitor.

Adult↗
PubMed2000

Quantitative electromyography of the external anal sphincter in Parkinson's disease and multiple system atrophy.

The distinction of multiple system atrophy (MSA) from Parkinson's disease (PD) can be difficult, especially early in the disease. In MSA degeneration of sacral anterior horn cells (Onuf's nucleus) results in denervation-reinnervation of anal and urethral sphincter muscles, which can be recognized as neurogenic electromyographic (EMG) changes of motor unit potentials. Sphincter EMG has therefore been recommended as a test for distinguishing MSA from PD. Our results confirm the presence of marked neurogenic EMG changes of the external anal sphincter muscle in patients with probable MSA compared to healthy controls. However, in patients with probable PD, our quantitative EMG data show a scatter from normal to marked neurogenic changes and the degree of EMG abnormality is correlated to the duration of the disease. Thus an abnormal sphincter EMG cannot be taken as a strong indicator of MSA rather than PD in the individual patient, especially in long-standing cases.

Adult↗
PubMed2000

Physiologic basis of potentials recorded in electromyography.

The extracellularly recorded configuration of a single muscle fiber discharge is generally appreciated to be triphasic with an initially positive deflection. However, careful attention to waveform appearance during the electrodiagnostic medicine examination reveals that both innervated and denervated muscle waveforms may display a pantheon of configurations. Further, despite the fact that innervated and denervated single muscle fiber discharges arise from distinctly different intracellular action potential (IAP) configurations, their extracellularly recorded waveforms can appear quite similar, leading to potential misidentification and, hence, the possibility of an erroneous diagnostic conclusion. The least appreciated, but nevertheless critical, aspect of explanations for muscle waveform configurations is the relationship between the muscle fiber and recording electrode. Additionally, it is important to appreciate both the near-field and far-field aspects of single fiber and compound muscle action potentials. In this review, the leading/trailing dipole model is used to explain muscle waveform configurations in both innervated and denervated tissues.

Electromyography↗
PubMed2001

Discharge patterns of spontaneous activity and motor units on concentric needle electromyography.

We analyzed discharge patterns in electromyograms of 6 patients with complete nerve lesions and of 26 healthy subjects, in order to better differentiate between pathological and physiological spontaneous electromyographic (EMG) activity. Within 1639 trains of action potentials, the intervals between at least five successive discharges were measured. Discharge regularity was evaluated with three different algorithms. At 99% specificity, an abnormal discharge pattern was identified with 91 to 95% sensitivity, depending on the algorithm used. Analysis of as few as four successive interdischarge intervals allowed reliable differentiation between normal and pathological spontaneous EMG activity.

Action Potentials↗
PubMed2001

Telemetered electromyography of the supinators and pronators of the forearm in gibbons and chimpanzees: implications for the fundamental positional adaptation of hominoids.

Extant apes are similar to one another, and different from monkeys, in features granting them greater range of forearm rotation and greater size of the muscles that produce this motion. Although these traits may have been independently acquired by the various apes, the possibility arises that such features reflect adaptation to the stem behavior of the hominoid lineage. Anticipating that knowledge of forearm rotatory muscle recruitment during brachiation, vertical climbing, arm-hanging during feeding, and voluntary reaching might point to this stem behavior, we undertook telemetered electromyographic experiments on the supinator, pronator quadratus, ulnar head of pronator teres, and a variety of other upper limb muscles in two gibbons and four chimpanzees. The primary rotator muscles of the hominoid forearm were recruited at high levels in a variety of behaviors. As had been suspected by previous researchers, the supinator is usually active during the support phase of armswinging, but we observed numerous instances of this behavior during which the muscle was inactive. No other muscle took over its role. Kinetic analyses are required to determine how apes can execute body rotation of armswinging without active muscular effort. The one behavior that is common to most extant apes, is rare in monkeys, and which places a consistently great demand on the primary forearm rotatory muscles, is hang-feeding. The muscles of the supporting limb are essential to properly position the body; those of the free limb are essential for grasping food. Since the greater range of forearm rotation characterizing apes is also best explained by adaptation to this behavior, we join previous authors who assert that it lies at the very origin of the Hominoidea.

Adaptation, Physiological↗