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At least 1,495 records · Page 83Linked to original sources
PubMed1994

Influence of muscle temperature and forearm position on evoked electromyography in the hand.

We have examined the correlation between the evoked electromyographic response in the first dorsal interosseous muscle of the hand, temperature and forearm position in 40 female patients after enflurane anaesthesia with spontaneous breathing. In 20 patients the supinated forearm with the wrist extended was immobilized on an armboard with adhesive tape (group A). In the other 20 patients (group B), the hand was strapped into a fist with adhesive tape and laid supine on an armboard. During the 30 min after induction of anaesthesia, the mean response to the first stimulus in the train-of-four was the same in both groups and decreased from a baseline value of 99.7% (95% confidence interval (CI) 99.1-100.4%) to 86.2% (95% CI 83.3-89.0%). The final response was less than 90% of baseline in 28 patients. There was an inverse linear correlation between the electromyographic response and both skin and muscle temperature in both groups (r > 0.98), although there was no correlation between change in the electromyogram and change in temperature (r < -0.26). After 30 min, pronation of the forearm resulted in a further decrease in the electromyographic response in 13 of 18 patients in group B (two patients in this group were excluded from analysis). Pressure was then applied to the scaphoid tubercles of all patients to produce maximal supination of the forearm. This had no effect on the electromyogram in 10 patients. In 28 patients the electromyographic response increased after scaphoid pressure, although it remained 90% of baseline in five patients. The measured temperatures did not alter during these manoeuvres.

Anesthesia, General↗
PubMed1994

Influence of serum concentrations of catecholamines and i.v. or volatile anaesthesia on evoked electromyography in the hand.

We have examined the correlation between serum concentrations of catecholamines and the evoked electromyographic (EEMG) response from the first dorsal interosseous muscle of the hand in 20 patients during minor surgery under propofol or enflurane anaesthesia without neuromuscular blocking drugs. The supinated forearm, with the wrist fully extended, was strapped firmly to an armboard and immobilized with adhesive tape. In the propofol group, the mean EEMG response to the first stimulus in the train-of-four (T1) decreased to 83.0% (95% confidence intervals (CI) 78.7-87.3%) of baseline, while in the enflurane group the mean EEMG T1 response decreased to 84.0% (95% CI 81.6-86.4%) of baseline. The decrease in the EEMG response occurred over 20 min and did not correlate with plasma concentrations of adrenaline or noradrenaline (correlation coefficients all < 0.26). We conclude that the decrease in EEMG response during the first 30 min of anaesthesia occurred during both i.v. and inhalation anaesthesia, and that changes in plasma concentrations of catecholamines did not cause the decrease in the EEMG response.

Anesthesia, General↗
PubMed1981

Surface versus intramuscular electrodes for electromyography of superficial and deep muscles.

The relative selectivity of surface electrodes placed over the gastrocnemius and soleus muscles in the standard manner was determined by comparing the electromyogram from these electrodes to the electromyogram from wire electrodes inserted into the soleus, gastrocnemius, and tibialis posterior muscles. Muscle activity was elicited in 11 normal subjects by performing six manual muscle tests. Three of the tests followed the standard technique and three were modifications designed to provide better differentiation of muscle action. All electromyographic data were quantified by computer integration and normalized to cancel out sampling inconsistency. None of the muscle tests totally restricted activity to the designated muscle, but the tests did determine which was the strongest participant. During the standard specific gastrocnemius and soleus muscle tests, the corresponding surface electrode provided a lower electromyogram than did the matching wire electrode; that is, the surface-to-wire-electrode ratio was less than one (gastrocnemius = 0.74, soleus = 0.58). This ratio was greater than one when the electromyogram was being recorded from one muscle while testing another muscle (gastrocnemius = 1.55, soleus = 1.92). The mathematical model relating surface-electrode values to the wire-electrode data from all three muscles identified 60 percent of the surface gastrocnemius electrode electromyogram as arising from that muscle, while only 36 percent of the soleus surface electrode data related to the activity of the soleus: Sg = .19Ws + 60Wg + .13Wt + .08Wo and Ss = .36Ws + .31Wg + .22Wt + .11Wo.

Electrodes↗
PubMed1982

Electromyography of the quadriceps femoris muscles in subjects with normal knees and acutely effused knees.

The purpose of the study was to describe the electrical activity of the vastus medialis, rectus femoris, and vastus lateralis muscles in subjects with normal knees and acute, severely effused knees when contracting maximally at 30 degrees and 0 degrees of knee flexion. Two groups identified were 1) an effused group (n=8) with subjects having one effused knee and one normal knee and 2) a normal group (n = 8) with subjects having two normal knees. The results were evaluated on two occasions by an observer who has unfamiliar with the groups to which the subjects belonged. The repeated evaluation yielded a high reliability coefficient (Spearman Rho r = .91). Analysis revealed a marked decrease in electrical activity at 0 degrees knee flexion compared to 30 degrees knee flexion in all muscles monitored in the effused knees, while the electrical activity was about equal in both joint positions for the normal knees in both groups. A hypothesis was formed that suggests the decreased electrical activity at 0 degrees in the effused knees results from reflex inhibition caused by joint capsule distension and intra-articular pressures that change with joint position.

Adolescent↗
PubMed1984

Electromyography in biomechanics.

The purpose of this paper is to discuss the use of EMG as related to biomechanical function and dysfunction. The uses and limitations of this technique are described and instrumentation features and methods of data collection and interpretation are presented. We also discuss factors that influence the relationship of EMG to biomechanical measurements and cite as examples studies that have used EMG. Emphasis is placed on improving the ability of the physical therapist to use and interpret EMG data in kinesiology and biomechanics.

Biomechanical Phenomena↗
PubMed1985

Electromyography results of exercise overflow in hemiplegic patients.

The purpose of this study was to determine the effects of exercise overflow in hemiplegic patients. Eleven subjects with a diagnosis of cerebrovascular accident (CVA) performed active exercises with their uninvolved extremities while their involved extremities were monitored with EMG. The muscles monitored were the biceps brachii, triceps brachii, and quadriceps femoris. Active exercise of the comparable uninvolved muscles was performed under three different weight lifting conditions: 1) maximal weight, 2) 50% of the maximal weight, and 3) no weight. Significant (p less than .05) overflow to the involved nonexercised extremities was found in all of the exercise conditions. Overflow was frequently found in all three muscle groups when only one muscle group was being exercised. Overflow always occurred in the contralateral homologous muscle. Exercise overflow appears to be an effective therapeutic technique to facilitate muscle activity in paretic muscles. This muscle activity may cause desired or undesired muscular effects during therapy in the rehabilitation of patients with CVAs.

Adult↗
PubMed1986

Electromyography and motion analysis of the upper extremity in sports.

This article reviews the results of studies using electromyographic recordings to determine muscle function during athletic activities. Electromyographic recordings were synchronized with high-speed film to provide information on shoulder muscle firing patterns during baseball pitching, swimming, tennis, and golf. The information obtained about the contributions of specific muscles during these activities may be useful in developing effective injury prevention and rehabilitation strategies.

Baseball↗
PubMed1987

Reliability of computerized surface electromyography for determining the onset of muscle activity.

The reliability of a computerized analysis system (CAS) for determining muscle burst onset was compared with the subjective assessments of three trained examiners. A sample of 154 randomly selected, full-wave rectified and filtered electromyographic recordings was evaluated using a test-retest paradigm. Percentages of agreement, Pearson product-moment correlations, analyses of variance (ANOVAs), and intraclass correlation coefficients (ICCs) were used to measure the reliability. The between-rater agreement, which included the computerized EMG assessments, was only 23%. Within-rater agreement and Pearson correlation coefficients were perfect for CAS. The trained examiners' within-rater assessments averaged only 51% agreement, but test-retest correlations were high (r = .78 - r = .82). All ICCs were statistically significant, ranged from .46 to .60, and tended to be higher when the CAS onset determinations were deleted from the analysis. The ANOVAs revealed that trained examiners were more consistent among each other than when their assessments were compared with CAS assessments of EMG recordings. This finding, however, may be facility-specific in that any generalization to other examiners was limited. In contrast to trained examiners, the CAS was free of variations in judgment, ensured perfect reproducibility of trial assessments, and was highly useful for analyzing multi-channel EMG recordings. Although the CAS ensures perfect reliability, validity determinations require visual inspection of trial data.

Adult↗