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At least 1,135 records · Page 63Linked to original sources
PubMed1987

Stapedial muscle electromyography in various diseases.

Stapedial muscle electromyograms (SEMGs), obtained by an averaging technique of electrocochleography, were studied in patients with various diseases. The latency of SEMG was prolonged in incomplete facial palsy (Bell's palsy and cerebellopontine angle tumor), with stapedial reflex (SR) of a small amplitude or without SR. In otitis media with effusion, in which SR could not be obtained, SEMGs were clearly observed and showed normal waveforms and latencies. In Meniere's disease and sensorineural hearing loss, SEMG waves had normal waveforms and latencies. These results indicate that the SEMG shows a normal waveform and latency when facial nerve function is intact, and that its latency is prolonged in incomplete paralysis of the facial nerve.

Adult↗
PubMed1990

Manometry and electromyography of the pharyngeal muscles in patients with dysphagia.

Simultaneous recording of the electromyographic activity of the pharyngeal muscles and the intraluminal pressure in the upper sphincter zone was performed routinely in patients with swallowing problems for the first time, to our knowledge. This technique was found to be very useful for the localization of the "site of lesion." The procedure is safe, easy to master, and causes minimal inconvenience. It can reveal, in the most direct way, whether the disturbance is in the hypopharyngeal musculature (represented by the inferior constrictor muscle), in the cricopharyngeal muscle (spasm or lack of relaxation), or in the synchronization between them. Simultaneous recording of intraluminal pressure adds valuable information about the mechanical events associated with electromyographic activity. It was found that in pathologic cases there is quite often no correlation between the electrical and mechanical events. Thus, simultaneous recording of both electrical and mechanical events is essential for the understanding of the pathophysiology of disturbances of deglutition.

Adult↗
PubMed1986

Facial electromyography in depression. Subgroup differences.

To study whether facial electromyographic (EMG) activity during affective imagery differed between normal subjects and depressive subtypes, we evaluated EMG responses in 29 normal controls, 37 endogenously depressed patients, and 26 nonendogenously depressed patients. Different imagery states produced more distinctive EMG patterns in normal controls than in depressed patients. Patients with endogenous depression had EMG levels that differentiated them from normal subjects and had significantly greater absolute values than the nonendogenous group in corrugator happy and corrugator sad imagery trials. Intensity of sad and happy imagery, age, and severity of depression did not systematically correlate with EMG activity among depressive subtypes.

Adult↗
PubMed1996

Combined electromyography--31P-magnetic resonance spectroscopy study of human muscle fatigue during static contraction.

Metabolic changes measured by 31P-magnetic resonance spectroscopy and surface electromyograms were simultaneously recorded during isometric contraction of forearm flexor muscles sustained at 60% of maximal force until exhaustion. Throughout the fatigue trial, energy in the low-frequency (L) band continuously increased whereas energy in the high-frequency (H) band first increased and fell only prior to exhaustion. PCr content decreased linearly. Intracellular pH (pHi) transiently increased during the first 22 s of trial. The triggering of acidosis was associated with critical PCr values (35-70% of initial content) and decreased electromyogram (EMG) energy in the H band. Linear relationships were only found between energy in the L band, pHi, and PCr content. The interindividual variability of metabolic and EMG changes was high despite standardized conditions of contraction. Maximal PCr consumption was correlated with the maximal pHi decrease measured at the end of the trial. Overall, there was no correlation between H/L EMG ratio and changes in muscle metabolism.

Adult↗
PubMed1997

End-plate electromyography: use of spectral analysis of end-plate noise.

An automated technique for estimating the channel open time of human end-plate acetylcholine receptors (AChR) is described. The method, which is based on the power spectral analysis of electromyographic end-plate noise, is simple and permits a rapid estimation of the dominant AChR ion channel kinetics. Values of AChR channel open time determined by spectral analysis of end-plate noise in adults (1.23 +/- 0.01 ms at 33 degrees C) were consistently shorter than those estimated from the decay phase of extracellularly recorded miniature end-plate potentials. The channel open time extracted from the end-plate noise compared well with that derived from the analysis of in vitro recorded acetylcholine-induced current noise. Therefore, spectral analysis of end-plate noise may provide a good estimation of the kinetics of the human AChR ion channel. The technique is particularly useful in identifying congenital myasthenic syndromes with altered AChR ion channel function.

Adult↗
PubMed1997

Postpolio muscular dysfunction: relationships between muscle energy metabolism, subjective symptoms, magnetic resonance imaging, electromyography, and muscle strength.

Eleven patients with previous polio were studied. The concentration of energy-related metabolites and energy charge was measured from the vastus lateralis muscle, as was isometric muscle strength of knee extension. Cross-sectional area of the quadriceps femoris muscle was calculated from magnetic resonance imaging. Reinnervation was studied using macroelectromyography. Muscle weakness, pain, and newly acquired muscle weakness in the legs was estimated by the patients. The findings in the legs in which the patients experienced new loss of muscle function were compared with the stable legs. There were no significant differences between these groups in any of the objectively measured variables. Only hip pain correlated with new loss of muscle function. Creatine phosphate was decreased in 5 patients. The symptoms and subjective muscle strength did not correlate with any of the objective measurements. There were no significant relationships between energy-related metabolites and postpolio symptoms.

Adult↗
PubMed1997

Smooth muscle electromyography from rat urethra.

Electrical signals recorded from the penis have been suggested as reflecting electromyographic activity in the underlying smooth muscles. In order to verify this assertion, we manipulated the signal recorded from rat urethra surface. Stimulation of the pelvic nerve brought about a reduction of activity (965 +/- 826 to 166 +/- 143 microV, root mean square of the power at range 0.005-1 Hz, P = 0.008), with a significant frequency-response relationship (P = 0.0002). This effect was not altered by temporary closure of the aorta (P = 0.89), thus ruling out hemodynamic artifact as a possible cause of signal change during stimulation. Our findings support the assertion that the signal indeed reflects activity in smooth muscle.

Animals↗
PubMed1998

Motor unit size estimation of enlarged motor units with surface electromyography.

Surface EMG is hardly used to estimate motor unit (MU) characteristics, while its non-invasiveness is less stressful for patients and allows multi-electrode recordings to investigate different sites of the muscle and MU. The present study compares motor unit potentials (MUPs) obtained with surface EMG and macro EMG during voluntary contraction of the biceps brachii muscle of patients with enlarged MUs caused by prior poliomyelitis. Averaged surface MUPs were obtained by means of needle EMG (SMUP1) and surface EMG (SMUP2) triggering. The MUPs area and peak amplitudes correlated well when comparing the macro MUP and SMUP1 of the same MUs. When MU populations of different patients were compared, the SMUP1s and SMUP2s were equally sensitive to pathology as macro MUPs. In this, the late non-propagating positive wave (only present in unipolar recordings) is more robust than the triphasic propagating wave. Therefore, surface EMG can be used for detecting enlarged MUs.

Adult↗