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At least 1,243 records · Page 69Linked to original sources
PubMed1999

Electromyography of the perioral and masticatory muscles in orthodontic patients with atypical swallowing.

Subjects with an open bite and an atypical swallowing pattern before (n = 20) and after (n = 10) orthodontic treatment and subjects with a normal swallowing pattern (n = 15) were examined. The electromyographic (EMG) activity of the upper and lower lips in the region of the modiolus and of the mentalis, masseter and temporal muscles was evaluated during the swallowing of saliva and of water and after the chewing of peanuts as well as during maximal biting in intercuspal position. During swallowing the atypical swallowers exhibited larger EMG activities of the perioral muscles and smaller EMG activities of the masticatory muscles than the control subjects. During maximal biting in intercuspal position, major EMG activity of the masseter and temporal muscles and minor EMG activity of the perioral muscles were recorded in both groups. No normalization of the electromyographic swallowing pattern could be observed during orthodontic treatment (closure of the open bite).

Adolescent↗
PubMed1986

Quantitative surface electromyography in anesthesia and critical care.

The frontalis muscle spontaneous (SEMG) and electrically evoked (EEMG) electromyograms were recorded in 4 different clinical settings. Using a standardized isoflurane-based anesthetic protocol. Study 1 examined the SEMG response to both surgical and acoustic stimuli. The acoustic SEMG response was also examined in comatose head-injured patients. Study 2 used the EEMG to compare the extent of vecuronium-induced neuromuscular blockade on the frontalis and hypothenar muscles in both anesthetized and comatose patients. In Study 3 head-injured comatose patients were used to investigate the relationship between SEMG changes and transient elevations in intracranial pressure (ICP). The effect of opiate analgesics on the pain-activated SEMG in conscious post-operative patients was investigated in Study 4. These studies illustrate the following phenomena. First, in conscious, unparalyzed or lightly anesthetized patients, painful (stressful) stimuli are associated with increases in SEMG amplitude. Thus, the SEMG may indicate periods of inadequate analgesia, not only post-operatively (Study 4) but also intra-operatively (Study 1), since we found the frontalis to be relatively insensitive to a non-depolarizing neuromuscular blocker (Study 2). However, the interpretation of intra-operative SEMG changes may be confounded by opiates (Study 4) and perhaps other agents capable of influencing the frontalis through either non-nociceptive central or peripheral mechanisms. Second, the opiate analgesics consistently decreased SEMG amplitude in non-tolerant conscious patients (Study 4. Although this opiate-induced decrease is not necessarily indicative of opiate analgesia, it may provide an objective, quantifiable measure of a central opiate effect. The SEMG is particularly well-suited to determine the precise timecourse of this effect. Third, in deeply anesthetized or comatose patients, unresponsive to either surgical or electrical stimulation. SEMG amplitude may increase in response to elevated ICP or certain sounds (Study 3). The stress (pain) and auditory-evoked SEMGs may thus provide measures of brainstem function that are independent of the level of consciousness.

Adult↗
PubMed1990

A comparison between electromyography and anal endosonography in mapping external anal sphincter defects.

Mapping of the external anal sphincter by anal endosonography was compared with the electromyographic findings in 15 patients with fecal incontinence after perineal trauma. Both examinations showed no defect in three patients. In the 12 patients with muscle defects, there was agreement on the quadrant involved in all patients. In seven patients, there was total agreement in the hours of the defect, in four there was a one hour discrepancy, and in one there was a two-hour difference in the measured defect. Correlation between the two techniques was high (r = 0.96; P less than 0.01). Anal endosonography is better tolerated by patients than electromyographic mapping and is a useful technique for assessing posttraumatic defects of the external anal sphincter.

Adolescent↗
PubMed2004

New method using multi-regression analysis on evoked electromyography during movement to adjust stimulation conditions.

A new method of stimulation of the lower extremities was devised that automatically adjusts the stimulation conditions at any angle of the knee joint. An M-wave is considered to indicate the stimulation conditions, because it is the waveform that results from direct stimulation to the axon of the alpha motor neuron. The present device adjusted the stimulation intensity, using multi-regression analysis to evoke an M-wave of preset amplitude. Participants included five people without any neuromuscular impairment. The subjects sat on a chair during the test. The hip joint was fixed at a flexion angle of 90 degrees, and the ankle joint was fixed at the midposition. During passive knee joint movement ranging from 0 degrees to 135 degrees, M-waves were measured. Electrodes were attached at the popliteal fossa and the patella to stimulate the tibial nerve. Ag-AgCl electrodes were put on the belly of the right soleus muscle for the M-wave measurement. The device was set to give M-waves close to the preset value, 10% Mmax. According to previous research, the allowable limit of M-wave amplitude deviations was reported to be about 5% Mmax. The M-wave amplitudes evoked by the device were in the allowable range (9.2 +/- 2.5% Mmax). The device enabled control of the M-wave amplitude over the entire range of motion of the joint. Using this device, it was possible to examine the excitability of the alpha motor neuron pool more precisely.

Adult↗
PubMedDate not supplied

Muscle electric activity. II: On the feasibility of model-based estimation of experimental conditions in electromyography.

From regular one-channel registrations of single muscle fiber action potential no measures on the recording configuration can be derived. When multichannel recordings are made, experimental parameters such as the distance between muscle fiber and needle electrode can be estimated. With the help of a volume conductor model, the single fiber activity at each of the electrodes can be predicted as a function of the recording conditions. Within known physical and physiological constraints such a model approach can be inverted (the inverse model) and used to estimate basic experimental conditions. From eight simultaneous single fiber action potential recordings we estimated (a) the distance between fiber and needle, (b) the axial position of the needle with respect to the muscle fiber, (c) a factor related to the muscle tissue anisotropy, and (d) a factor combining the muscle fiber diameter and the effective muscle tissue conductivity. With the help of a model describing the influence of the needle shaft it is made plausible that the needle inhomogeneity influences the results of the proposed procedure.

Action Potentials↗
PubMed1989

Electromyography of lumbar erector spinae muscles--influence of posture, interelectrode distance, strength, and fatigue.

The aims of the study were to obtain information (1) on surface electromyograms (SEMG) from the lumbar erector spinae muscles at different interelectrode distances and postures during short isometric contractions with constant force, (2) on the relationships between SEMG and extension force at different postures, and (3) on changes in SEMG during fatiguing isometric contractions at different postures and strengths. Six male subjects developed target forces in prone postures without gravity confounding the measurement of the extension torque. The angles between the constantly horizontal upper trunk and thighs were 90 degrees (P1), 135 degrees (P2), 170 degrees (P3), and 190 degrees (P4). Standard deviations of the distribution of SEMG amplitudes (RMS values), autoregressive (AR) time series models of the 15th order and spectral densities, including mean power frequency (MPF), were computed. Smaller interelectrode distances accompanied smaller RMS values and higher MPF. At a constant extension torque of about 110 Nm, RMS values and MPF increased from P1 to P4. Changes of interelectrode distance were of relatively minor importance, compared with the variation in the posture. With increasing torque, the increase in RMS values was steeper at P3 than at P2. The AR structure and MPF did not exhibit distinct effects of force. During sustained contractions at P2 and P3, only the highest force (mean = 140 Nm) at P3 caused a significant decrease of the MPF at the very beginning of the contraction. Endurance at P2 was greater than at P3. Higher forces and/or shorter muscles (P3) induced more pronounced and earlier relative decreases of the MPF and residual variance of AR models. Up to the "failure point", RMS values increased slightly, but without significant differences.

Adult↗
PubMed1998

Requests for electromyography from general practitioners and specialists: critical evaluation.

In order to improve the quality of service and limit costs of a local electromyographic service, the requests for electromyographic (EMG) examination issued by general practitioners and specialists were critically evaluated. The diagnoses suspected by referring doctors were compared with medical history and clinical data to analyze (1) the utility of EMG for the final diagnosis and (2) the concordance with that of the neurophysiologist and with the EMG results. In 1994 and 1995, there were 3482 patients referred to the EMG service. Only patients undergoing EMG for the first time (2706 subjects) were considered. In 76.6% of cases, the referring doctor had indicated the suspected diagnosis in the request. This diagnosis was compatible with medical history, symptoms and the results of neurological examination in 57.6% of cases. In 77.2%, the neurophysiologist considered the EMG useful in confirming the clinical diagnosis. The suspected diagnosis was confirmed by the clinical diagnosis of the neurophysiologist and by the EMG results in 54.2% and 45.4% of cases, respectively. When the request was issued by neurosurgeons, neurologists, orthopedists, rheumatologists and physiatrists, the suspected diagnosis was more accurate; as a consequence the EMG was more correctly oriented than when the request was issued by other specialists or by general practitioners. It is recommended that neurological examination be a prerequisite for EMG requests issued by general practitioners.

Cost-Benefit Analysis↗
PubMed1989

Ag/AgCl electrode assembly for thin smooth muscle electromyography.

An electrode assembly for in vivo recording of the electrical activities of thin muscular layers is described. It comprises an active electrode surrounded by a ring, which avoids the recording of interfering signals. An improved technique for chlorinating the silver electrodes is presented: a partial electrolytic removal of an initial thick deposit is performed. This decreases the impedance, and lowers the ageing degradation of the electrodes in vivo. Recordings of extremely low frequency signals are allowed, whereas standard Ag/AgCl electrodes are inefficient when recording signals in the frequency domain under 0.1 Hz. The technical features which are described can be adapted to any Ag/AgCl electrode developed for in vivo measurements.

Animals↗
PubMed1996

Corpus cavernosum electromyography (CC-EMG): a new technique in the diagnostic work-up of impotence.

We have studied cavernous electrical activity in 42 subjects, healthy volunteer controls and groups of impotent patients using a nonspecific electromyographic device (PICO-MENFIS) and a specific one, the SPACE-recorder 7500 designed to achieve electric recordings from the corpora cavernosa. In all of the patients, we detected under basal conditions a mean amplitude of 583 +/- 323 microV, a mean duration of 4.9 +/- 7 s, a mean polyphasicity of 3.5 +/- 1.4. It should be emphasized that a significant reduction of potential amplitudes was recorded after pharmacological stimulation in both the controls and the impotent patients. The healthy controls showed amplitudes significantly higher than the impotent patients after radical cystectomy (715 +/- 141 microV versus 381 +/- 227 microV, p < 0.01). The patients after a "nerve-sparing" radical cystectomy with a mean amplitude similar to the controls (500-700 microV) reacted well to the intracavernous drugs in a high percentage of cases. In our experience, CC-EMG seems to be a reliable method which can pinpoint directly lesions to the cavernous smooth muscle and penile autonomic nerves. It has also been able to assess the effects of stress, anxiety and pain on the erectile mechanisms.

Adolescent↗