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PubMed1985

Single fiber electromyography with a standard monopolar electrode.

A technique of obtaining qualitative single fiber electromyography information with standard monopolar electrodes is described. The technique requires an electromyograph equipped with a trigger and delay line. Single fiber electromyography is an effective tool in dealing with disorders that affect neuromuscular transmission and for observing the recovery of nerve injuries. Since most problems encountered in clinical practice deal with the diagnosis and follow-up of radiculopathies and peripheral nerve compromise, the use of single fiber electromyography in these conditions is of great clinical importance.

Electrodes↗
PubMedDate not supplied

[Standard electromyography for the diagnosis and prognosis of laryngeal neuromuscular disorders].

The clinical use of the laryngeal electromyography is still scanty; nevertheless, in our experience it has been shown to be an efficient and objective test in the study of the neurological disorders of the larynx and in the prognosis of recovery after vocal cord paralysis. We have performed conventional electromyography of the thyroarytenoid and cricothyroid muscles in 25 patients with laryngoscopically--confirmed vocal cord paralysis of different etiology. Positive sharp waves, fibrillation potentials and decreased or absent activity on maximal voluntary effort provided enough evidence of denervation in those cases of neurogenic origin. An increased number of polyphasic potentials and increased length of the motor unit potentials recruited in reduced interference patterns were considered suggestive of reinervation, which has an outstanding prognostic value on laryngeal neuropathy. Voluntary motor units, even in some clinically non-mobile vocal cords, were identified in recruitment patterns. Laryngeal electromyography can be done as an office procedure with a minimum of discomfort. It gives objective evaluation of the neuromuscular status, and shows direct evidence of cord function, being useful to distinguish from supranuclear and mechanical disorders of the larynx. It has also shown to be efficient as recovery predictor after vocal cord paralysis.

Adult↗
PubMed1977

Chemonucleolysis: evaluation of effectiveness by electromyography.

Findings in 97 consecutive patients who had undergone chemonucleolysis were analyzed. The purpose of this prospective clinical study was two-fold: (1) to provide a comparison of preoperative findings of electromyography, myelography and discography and (2) to evaluate postoperative electromyography as an objective test of recovery. All the patients had complete history and physical examination, five-view roentgenographic study of the lumbosacral spine, electromyography preoperatively and again at three months postoperatively, myelography and discography. Computer analysis of the results was done for the multiple cross-correlations in the study. All patients had had at least three months preoperative conservative care without relief of symptoms. The study shows that electromyographic study three months postchemonucleolysis is of value for corroboration of clinical improvement only if the EMG becomes completely normal. A greater percentage of patients recovered clinically after chemonucleolysis when the preoperative EMG was normal as compared to those for whom the preoperative EMG was abnormal. We were surprised to find no significant correlation between end result and the existence of pending litigation.

Chymopapain↗
PubMed1998

Electromyography in near-total laryngectomy.

OBJECTIVE: To investigate the dynamics of speech shunt muscle in patients with Pearson near-total laryngectomy by needle electromyography and correlation of ability to activate shunt muscle with speech production. DESIGN AND SETTINGS: Prospective study of patients with near-total laryngectomy at 2 hospital-based academic tertiary care centers. PARTICIPANTS AND INTERVENTION: Fourteen patients with near-total laryngectomy were subjected to percutaneous needle electromyographic study of the shunt muscle. MAIN OUTCOME MEASURES: Speech ability, electromyographic evidence of viable muscle in shunt wall, and ability to activate shunt muscle were recorded. RESULTS: Twelve of 14 patients had good speech; 11 had evidence of viable shunt muscle; and 9 were able to activate muscle by phonation, swallowing, or deep breathing, indicating preserved innervation. Six of the 12 patients with speech ability and 1 of the 2 patients without speech ability were able to recruit motor units during attempted phonation. CONCLUSIONS: Electromyography demonstrated viable muscle with retained innervation in 64% of the patients with near-total laryngectomy, proving its "dynamic" nature. However, the usefulness of shunt muscle activation in speech and prevention of aspiration needs further confirmation.

Adult↗
PubMed1982

The diagnostic value of electromyography in infantile hypotonia.

There is controversy over the usefulness of electromyography (EMG) in the examination of hypotonic infants with suspected neuromuscular disease. We compared the initial EMG findings of 51 such children under 1 year of age with their final clinical diagnoses determined by independent means. The EMG predicted the final diagnosis in 82% of infants less than 4 months of age and 85% of those over 4 months of age. Botulism was correctly identified by EMG in nine of 11 cases. The EMG diagnosis was identical to that obtained by muscle biopsy in 64% of cases in which biopsy was done, and diagnosis obtained by the two methods were inconsistent in only 14%. Electromyography is a sensitive and noninvasive diagnostic tool for the diagnosis of neuromuscular disease in infantile hypotonia.

Electromyography↗
PubMed1993

The clinical differentiation between vocal cord paralysis and vocal cord fixation using electromyography.

With newer techniques for laryngeal intervention, it becomes a practical necessity to understand whether an immobile cord is due to neurogenic dysfunction or cricoarytenoid fixation. An objective test for this differentiation is laryngeal electromyography, which can be done as an office procedure with a minimum of discomfort. Our experience in a clinical setting has shown laryngeal electromyography to be efficient in accurately assessing the neuromuscular status of the intrinsic laryngeal musculature.

Adult↗
PubMed2002

Early struggles with single-fiber electromyography.

The development of single-fiber electromyography is described. This method, introduced in 1963, was met with doubts, and there were strong arguments that subunits, 10-30 synchronized muscle fibers, were in fact being recorded. The dispute ended in 1971, and single-fiber electromyography is now generally accepted.

Electromyography↗
PubMed2002

What have I learned from single-fiber electromyography?

The author recounts the lessons taught by single-fiber electromyography that reached him through the medium of low-frequency attenuation and a small concentric needle electrode. He concludes that it is difficult to imagine practicing electromyography today without the benefits that have flowed from the work of Erik Stålberg and his colleagues.

Electromyography↗
PubMed2002

Models and simulations in electromyography.

In electromyography, one assesses the pathophysiology on the basis of the waveform characteristics of the recorded signal. This requires detailed knowledge of the relationship between the waveform generators and the waveform measurements. Models and computer simulations can be used to explore this relationship in an efficient manner. Combining models with experimental methods will allow us to define new measurements and new rules of interpretation. This is discussed with some of the models developed for electromyography signal analysis.

Animals↗
PubMed1982

The diagnostic yield of quantified electromyography and quantified muscle biopsy in neuromuscular disorders.

Electromyography (EMG), histology, and histochemistry were related in 264 patients with neuromuscular disorders classified according to history and clinical and other laboratory findings. Electromyography and histological and histochemical abnormalities were divided in specific and nonspecific criteria. Specific histochemical criteria alone identified 28% of neurogenic lesions. Criteria of myopathy, obtained from the pattern of electrical activity during 30% of maximal effort, helped to delineate a myopathy when the only abnormality was an increased incidence of polyphasic potentials together with a pattern of full recruitment during maximal effort. Histology, histochemistry, or both, and EMG were concordant with clinical findings in 77% of 188 patients with myopathy and in 91% of 64 patients with neurogenic lesions. The electromyogram was concordant with the clinical classification in 87% of patients with myopathy and in 91% of patients with neurogenic impairment. The biopsy was in agreement with or contributed to the classification in 79% of patients with myopathy and in 92% of patients with neuropathy.

Adolescent↗
PubMed1988

The human cervical myotomes: an anatomical correlation between electromyography and CT/myelography.

To correlate the accuracy of electromyography in diagnosing the correct root involved in cervical radiculopathy, 20 patients with cervical radiculopathy, diagnosed by electromyography using strict inclusion and exclusion criteria, were studied. Metrizamide myelography/computerized tomography were evaluated in all 20 patients independently, and the involved root was defined. The root involved, using the EMG examination and the myotome chart of the Medical Research Council, was C5 in 3 patients, C6 in 6, C7 in 9 patients, and C8 in 2 patients. The overall correlation with myelography/CT was 65% (33.3, 66.6, 77.7, and 50% for C5, C6, C7, and C8, respectively). EMG done properly has a good correlation of myelography/CT. This correlation is higher (73.3%) for the commonly occurring cervical radiculopathies (C6 and C7).

Action Potentials↗
PubMed1989

Electromyography in congenital nemaline myopathy.

To clarify the discrepancies between earlier reports of electromyography (EMG) in congenital nemaline myopathy (CNM), conventional electromyography was done on 13 patients with CNM, and results were compared with those of 18 earlier EMG examinations of the same patients. Fiber density was measured in 10 patients with a computerized method and neuromuscular jitter in 3 with single-fiber EMG. With age, the EMG abnormality progressed, and "neuropathic" EMG features developed in distal muscles. In 9 of 10 patients fiber density was higher than normal. In two of three patients jitter was abnormal. Motor (13 of 13 patients) and sensory (3 of 3 patients) nerve conduction velocities were normal. Our results seem to explain the conflicting reports of EMG in CNM. We conclude that active degeneration and regeneration of muscle fibers takes place in CNM and suggest that the "neuropathic" motor unit potentials seen in our patients may be secondary to myopathic disease activity.

Adolescent↗
PubMed1994

Electromyography and biopsy correlation with suggested protocol for evaluation of the floppy infant.

Eighty infants with nonarthrogrypotic floppy infant syndrome (FIS) were evaluated between 1979 and 1990. Electromyographic data were correlated with results of muscle and nerve biopsies in 41 of 80 who had concomitant biopsies (38) or other diagnostic analyses (3). A diagnosis was made of Werdnig-Hoffmann disease (WHD) in 15, a congenital infantile polyneuropathy (IPN) in 3, neuromuscular transmission defect (NMTD) in 2, myopathy in 12, and presumed "central" hypotonia in 9. A very positive correlation rate between nerve conduction studies with electromyography and biopsy results was found in 93% (14 of 15) with WHD and 100% in IPN (3 of 3). However, only 4 of 10 infants (40%) with biopsy-proven myopathy had an abnormal EMG. Only once did the results of electromyography and biopsy conflict.

Biopsy↗
PubMed1995

AAEM minimonograph #45: the early development of electromyography.

The use of electricity for therapeutic purposes began in the first century and became more refined as the properties of electricity became more understood. The works of Franklin, Galvani, Volta, and others contributed to this body of knowledge. Development of the string galvanometer, the advent of the vacuum tube, the introduction of concentric needle electrodes, and the development of the cathode-ray oscilloscope occurred during the first half of the 20th century. The science of electromyography and electrodiagnosis grew in its sophistication, leading to the formation of the American Association of Electromyography and Electrodiagnosis (now the American Association of Electrodiagnostic Medicine) with James Golseth, MD, as its first president in 1953.

Electromyography↗
PubMed1992

[Electromyography and functional analytic findings in obstructive disorders of defecation. A contribution to the differentiation of neurogenic and myogenic sphincter damage].

The aim of this study was to get further information about functional results in patients with outlet obstruction. We investigated 27 patients (age between 42 and 74 years) by electromyography (EMG), manometry and radiology with contrast-solution. The electromyography, a dynamic investigation method, allows the differentiation between neuronal and muscular malfunctions of the voluntary controlled pelvis muscles. Patients with outlet obstruction should be divided into three groups by EMG diagnosis: One group with neuronal alterations, another group with muscular alterations and one group with neuro-muscular alterations. We obtained marked statistical differences between patients with neuronal or muscular malfunctions in the mean amplitude, the turns per second and the integration of the mean amplitude compared to the control group (14 patients). Patients with only neuronal alterations showed furthermore statistically significant distinctions of the action potential duration from control, whereas the data of patients with muscular malfunctions were significantly different from control in the peak amplitude of the action potentials. 77% of all investigated patients were not able to relax the pelvis muscles during defecation.

Adult↗
PubMed1992

Electromyography of the pubococcygeus muscles in patients with obstructed defaecation.

The function of the pubococcygeus muscles during defaecation straining was compared in 10 women with obstructed defaecation and 12 age-matched control subjects. Video-proctography in each patient showed failure to evacuate the rectum and sagging of the pelvic floor during attempted defaecation. Trans-perineal concentric needle electromyography in the puborectalis muscle and transvaginal electromyography in the pubococcygeus muscle was carried out during defaecation straining and during attempted rectal balloon expulsion. Contraction of the pubococcygeus muscle was observed in 10 of the 12 control subjects and in 2 of the 10 patients with obstructed defaecation (P < 0.005). Virtually equal proportions of subjects in each group showed relaxation or contraction of the puborectalis muscle during straining. There was significant perineal descent on straining in the patient group (P = 0.005). This group of patients with obstructed defaecation showed failure of the pubococcygeus muscles to contract, perhaps due to neuropathic weakness of the muscles. The puborectalis muscle did not cause obstructed defaecation in these patients, and the concept of "paradoxical" contraction of this muscle is questioned.

Adult↗
PubMed1994

Reproducibility of computer measurement of maximal isometric strength and electromyography in sedentary middle-aged women.

The objectives of this study were (i) to determine the reproducibility of computer measurements of isometric strength and related electromyography in several muscle groups in sedentary middle-aged women, (ii) to evaluate the effects of different digital signal averaging methods on the reproducibility, (iii) to determine the final test score to be preferred in terms of improved reproducibility of isometric strength measurements, and (iv) to evaluate potential advantages provided by the computer measurement. Fifteen subjects were measured three times within a 2-week period. The measurements consisted of recordings of maximal isometric strength and rate of force production during trunk extension and flexion, leg extension and dominant forearm flexion with simultaneous recordings of surface electromyography, except in the trunk flexors. The following four final test scores were determined for each trial: the maximum of the three scores, the mean of the two highest scores, the median of the three scores and the mean of the three scores. The scores for the strength measurement were generally more reproducible (coefficient of variation, CV, approximately 6% and intraclass correlation coefficient ICCC, approximately 0.90) than those of the other measurements (CV > 10%, ICCC 0.13-0.97). There was no obvious preference for any type of final test score or for the width of the averaging window in the computer analysis. For isometric strength the reproducibility of the computer measurements was comparable to that of the voltmeter assessments. Computer analysis seems to be a versatile method for determining parameters of neuromuscular performance with reasonable reproducibility.

Computers↗
PubMed1995

Striated anal sphincter electromyography in idiopathic fecal incontinence.

PURPOSE: This study was designed to determine the importance of innervation of striated anal sphincters, one of the most important structures in idiopathic fecal incontinence. METHODS: Forty-three idiopathic, fecally incontinent patients (40 women and 3 men; mean age, 57.2 +/- 11 (range, 33-77) years) underwent anorectal manometry and sphincteric electromyography. On the basis of electromyographic findings, patients were subdivided into three groups: Group A consisted of 21 patients with normal electromyography; Group B consisted of 14 patients with moderate denervation; Group C consisted of 8 patients with severe denervation. Manometric results from the patients were compared with those from 15 healthy subjects (8 women and 7 men; mean age, 35 +/- 12 (range, 15-55) years). RESULTS: Incontinent patients had a shorter anal canal (P = 0.005), and anal canal pressure was lower at rest (P < 0.001), at contraction (P < 0.001), and at coughing (P < 0.001); rectal distention and rectal compliance were reduced (maximum tolerated volume, P < 0.003; compliance at 200 ml, P = 0.03; at 250, P < 0.005; at 300 ml, P = 0.03). No statistically significant differences were found between the manometric results of the three different groups of patients. A statistically significant linear correlation was reached by comparing the clinical severity of fecal incontinence with age (P = 0.02) and some other manometric parameters: the pressure of the anal canal at rest (P < 0.001) and at contraction (P < 0.01); rectal compliance at 50 ml (P = 0.03), 100 ml (P = 0.004), and 150 ml (P = 0.004). CONCLUSION: Clinical severity of fecal incontinence is correlated with some manometric parameters. Severity of denervation of the anal striated sphincters does not appear to influence severity of fecal incontinence.

Adult↗