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PubMed1996

Electromyography of the perineal floor.

Electromyography is the study of minute potentials produced by the depolarization of the muscle membrane; they may be useful in the diagnosis of pelvic floor disorders. Either surface or needle electrodes may be used, depending on the type of information desired. Innervation deficits may be indicated by abnormal potentials observed in resting or active muscle. Electromyography is also useful in assessing coordination between bladder contraction and sphincter relaxation.

Artifacts↗

PubMed1999

Role of motor unit number estimate electromyography in experimental canine laryngeal reinnervation.

Laryngeal electromyography has been used clinically to differentiate neuromuscular pathology from other causes of vocal fold immobility such as arytenoid dislocation, tumor invasion, or cricoarytenoid joint fixation. Electromyography has also been used to predict the prognosis for nerve recovery in laryngeal paralysis. Existing electromyographic techniques either record activity with voluntary motion or study nerve conduction. In this study a new technique, motor unit number estimation, a commercially available quantitative method of electromyographic analysis, is used to study the progress of recovery of vocal fold function after recurrent laryngeal nerve injury. Four dogs underwent transection and immediate reanastomosis of selected branches of the adductor and abductor branches of the recurrent laryngeal nerve on 1 side; the opposite side served as a control. Baseline electromyographic and videolaryngoscopic studies were performed. These measures were then repeated in a longitudinal fashion every 6 weeks after denervation. The motor unit number estimation technique indicated a return of motor unit numbers with time, along with estimates of their size. This was consistent with the expected progress of laryngeal reinnervation. These data and their predictive value for nerve recovery will be discussed.

Anastomosis, Surgical↗

PubMed2003

The effectiveness of neuromuscular facial retraining combined with electromyography in facial paralysis rehabilitation.

OBJECTIVE: The study goal was to present the effectiveness of neuromuscular facial retraining techniques used in combination with electromyography for improving facial function even in cases of longstanding paralysis. STUDY DESIGN AND SETTING: We conducted a retrospective case review in a tertiary neurotology clinic. PATIENTS: Twenty-four patients with facial paralysis received neuromuscular facial retraining between April 1999 and April 2001. The patient sample included 6 males and 18 females, with an average age of 44 years. A control group consisted of 6 patients (4 females and 2 males). RESULTS: All patient groups made significant improvements in function with improved symmetry in dual-channel electromyographic readings and increased facial movement percentages. Some of the percentages of posttreatment facial function were as follows: acoustic neuromas, 93%; Bell's palsy/Ramsay Hunt syndrome, 80%; and facial nerve anastomosis, 71%. Synkinesis was reduced by at least 2 levels in patients who initially demonstrated synkinesis. CONCLUSIONS: Neuromuscular facial retraining exercises and electromyography are effective for improving facial movements. SIGNIFICANCE: Facial retraining is an excellent example of the plasticity of the central nervous system to reorganize, even in cases of longstanding paralysis.

Adolescent↗

PubMedDate not supplied

Intraoperative evoked electromyography in Bell's palsy.

The technique of intraoperative evoked electromyography is described in detail. Direct intraoperative stimulation of the exposed facial nerve identified the sites of nerve impulse conduction blocks in 16 of 18 patients who needed decompression for Bell' s palsy. In order to determine the site of impulse conduction block the test must be performed before 100 per cent nerve degeneration occurs. The lesions extended only a few millimeters and were found to be proximal to the geniculate ganglion in 15 (94 per cent) of these patients. Schirmer's test correctly identified the sites of the lesions in only 61 per cent of the patients. To locate the precise site of the lesion inducing a conduction block in Bell's palsy, intraoperative evoked electromyography must be used. The limited extent of the blocked motor fibers indicates that segmental rather than total intratemporal decompression is needed in Bell's palsy.

Electromyography↗

PubMed1990

Dynamic electromyography to assess elbow spasticity.

Control of elbow motion was evaluated in 45 extremities of adults with spasticity resulting from traumatic brain injury with use of dynamic electromyography. Simultaneous recording of elbow motion was obtained using a double parallelogram goniometer. Thirty-four male and 9 female patients were studied. Mean elbow flexion was 85 degrees and mean extension was 20 degrees. The average time of elbow flexion was 1.8 seconds. Extension time was prolonged to a mean of 4.0 seconds. Dynamic electromyography revealed a consistent pattern of muscle activity. Severe spasticity was noted in the brachioradialis muscle. Moderate spasticity was present in the biceps and only mild spasticity was seen in the brachialis muscle. Normal phasic muscle activity was the rule in the triceps. All patients had active elbow flexion, but the flexor spasticity limited smooth extension. Elbow flexor spasticity, especially of the brachioradialis and biceps muscles, commonly interferes with hand placement. Lengthening of the biceps and brachialis tendons combined with release of the brachioradialis enhances elbow motion and improves hand placement.

Adolescent↗

PubMed2003

Vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma: laryngeal electromyography findings.

Laryngeal electromyography was used to study the pattern of neurological injury in three patients with unilateral vocal fold paralysis following radiotherapy for nasopharyngeal carcinoma. The thyroarytenoid and cricothyroid muscles were assessed to give an indication of recurrent and superior laryngeal nerve function. Two patients demonstrated both recurrent and superior laryngeal neuropathy suggesting injury at the skull base. The other patient had only recurrent laryngeal neuropathy indicating more distal involvement. Subclinical neuropathic changes were seen in two cases on the side contralateral to the vocal fold paralysis. These patients may be at increased risk of developing bilateral vocal fold paralysis and potentially life-threatening airway obstruction. Long-term follow-up is recommended for such patients, especially if medialization thyroplasty is being considered. This is the first report describing the use of electromyography to determine the pattern of nerve injury in patients with vocal fold paralysis following head and neck radiotherapy.

Carcinoma↗

PubMed1998

Electromyography during chewing movement in patients with anterior disc displacement of the temporomandibular joint.

The purpose of this study was to investigate the value of electromyography in patients with anterior disc displacement (ADD) of the temporomandibular joint (TMJ). Electromyography (EMG) during chewing movement was evaluated in 48 women with unilateral ADD of the TMJ (21 patients with ADD with reduction and 27 with ADD without reduction). As a control group, 31 women without TMJ dysfunction were evaluated. The duration of contraction, latency, cycle time, and integrated value on the EMG were measured in the patients and controls. There were significant differences between the patients and controls in the duration of contraction, cycle time, and integrated value. However, there were no differences in any measurements between the two subgroup patients. EMG appeared to be a method of documenting that masticatory function was impaired in patients with ADD.

Adolescent↗

PubMed2000

Use of surface electromyography to estimate neck muscle activity.

This paper reviews the literature concerning the use of surface electromyography (sEMG) for the study of the neck musculature in response to work and workplace design during light work and semi-static tasks. The paper also draws upon basic research and biomechanical modeling in order to provide methodological recommendations for the use of surface electromyography in this region of the body and to identify areas which require further investigation. The paper includes review and discussion of electrode site location, methods of normalization, data reliability, and factors that can affect sEMG signals from this region, including noise, physiologic artifact, stress, visual deficiencies, and pain. General guidance for maximum exertions with the neck musculature, for sEMG normalization or other purposes, is also included.

Biomechanical Phenomena↗

PubMed2006

Electromyography of the cricoarytenoid unit during supracricoid laryngectomy with a cricohyoidoepiglottopexy procedure.

Two patients who received supracricoid laryngectomy with cricohyoidoepiglottopexy to treat laryngeal cancers, underwent intra-operative electromyography analysis. After the lesion was removed and the electrodes were inserted into the remaining intrinsic laryngeal muscles, the depth of anaesthesia was carefully reduced. Gentle tactile stimulations were applied to the pharynx to trigger the reflex movement of the remaining arytenoids. Recordings were made when reflex movement was achieved. Case one: Electromyography (EMG) of the remaining arytenoid demonstrated clear phase differences indicating reciprocal activities between the adductor group (lateral cricoarytenoid muscle, interarytenoid muscle) and the abductor muscle (posterior cricoarytenoid muscle). Case two: EMG of the remaining arytenoid demonstrated reciprocal activities between the interarytenoid muscle and the posterior cricoarytenoid muscle. Activity of the lateral cricoarytenoid muscle was not evident because the muscle was excised during removal of the paraglottic space. Mobility of the arytenoid was attributed to interaction between the interarytenoid muscle and posterior cricoarytenoid muscle. Reciprocal interaction between the interarytenoid muscle and posterior cricoarytenoid muscle alone is also capable of maintaining post-operative laryngeal functions after supracricoid laryngectomy with cricohyoidoepiglottopexy.

Aged↗

PubMed1997

Motor unit potential contribution to surface electromyography.

The background of the bioelectric activity of muscle recorded from the surface of the skin (surface electromyography) in terms of the representation of single motor units of the underlying muscle(s) is not very well documented or understood. An insight into the composition of an electromyogram is essential for the proper interpretation of one of the most widely applied electrophysiological techniques. In the present paper, a study of the contribution of single motor unit potentials to the surface electromyogram is presented. To this end, the decline of different components of the motor unit potential with depth of the motor unit is quantified. Experimentally, the action potentials from motor units at several positions in the muscle were recorded by 30 skin surface electrodes. Simultaneous use of scanning electromyography provided information about the actual position and size of the motor unit. Observed linear log-log relationships between motor unit potential magnitudes and distance indicated the usefulness of a power function to describe the motor unit potential's dependence on recording distance. It is shown that different specific surface motor unit potential characteristics fall off differently with depth. The magnitude-distance relationship is shown to be dependent on the recording configuration (unipolar vs. bipolar recording, including the inter-electrode distance) and the chosen motor unit potential parameter (negative peak amplitude, positive peak amplitude and area).

Adult↗

PubMed2000

On-line quantitative analysis of surface electromyography of the pelvic floor in patients with faecal incontinence.

BACKGROUND: Needle electromyography (EMG) remains the 'gold standard' for the assessment of external anal sphincter innervation. It is, however, an invasive and poorly tolerated technique. In this study a quantitative form of surface electromyography was compared with needle EMG of the external anal sphincter. METHODS: Invasive needle EMG to assess mean fibre density and neuromuscular jitter was compared directly with quantitative surface EMG in 37 patients with faecal incontinence and 12 age-matched controls. RESULTS: There was a significant positive correlation between mean fibre density on needle EMG and maximum turns rate on surface EMG (rs = 0.48 (95 per cent confidence interval 0.28-0.76), P = 0.003). Furthermore, surface EMG was able to discriminate between patients with normal neuromuscular jitter and those with increased jitter, a measure of progressive denervation and reinnervation, on the basis of reduced rectified mean surface signal (P = 0.02, Fisher's exact test). CONCLUSION: Quantitative surface EMG may potentially replace invasive needle EMG as the investigation of choice in the assessment of anal sphincter electrophysiology.

Anus Diseases↗

PubMed1995

[Electrode applicator for endolaryngeal electromyography of the larynx with local anesthesia].

Electromyography of the internal laryngeal muscles is not yet a routine examination. To improve the technique, we developed a new applicator for easy and safe endolaryngeal placement of electrodes, which is now routinely used. Application of the electrodes is successful in a higher percentage of patients than with applicator forceps used previously. Additionally, the danger of displacement of needles within the pharynx or larynx and of injury of the mucosa has been completely eliminated. This application technique can be recommended for endolaryngeal placement of wire electrodes for laryngeal electromyography.

Anesthesia, Local↗

PubMed1986

Anorectal electromyography in the diagnosis of Hirschsprung's disease.

Anorectal electromyography using intraluminal electrodes was done in nine patients with Hirschsprung's disease and in nine control patients with chronic constipation. In chronic constipation, many bursts of spikes were seen in both the anal canal and the rectum corresponding to contractions of the external sphincter muscle. These were propagated from the anal canal to the rectum. In contrast, in Hirschsprung's disease few bursts of spikes were seen in the rectum, and they were not propagated from the anal canal to the rectum, even if they corresponded to contractions of the external sphincter muscle. Thus anorectal electromyography proved to be a useful screening test for Hirschsprung's disease. The bursts of spikes were analysed by a signal processor that provided more precise details for the diagnosis of Hirschsprung's disease.

Anal Canal↗

PubMed2001

Role of urethral electromyography in predicting outcome of Burch retropubic urethropexy.

OBJECTIVE: To establish preoperative urethral electromyographic parameters that predict which women are unlikely to be cured of genuine stress incontinence by Burch retropubic urethropexy procedures. STUDY DESIGN: Eighty-nine women who underwent preoperative urodynamic testing with urethral electromyography and retropubic urethropexy for genuine stress incontinence were prospectively studied. Raw electromyographic signals were processed by an electromyographic instrument equipped with automated motor unit analysis software programs. Quantitative electromyographic software was used to analyze the electrical activity of the urethral sphincter with use of mean rectified voltage (MRV)-mean amplitude calculated over the entire tracing after the waveform is rectified-with women at rest and during voluntary urethral squeezing, repetitive coughing, and bladder filling. Objective outcomes were determined 3 months after the operation with single-channel cystometrograms performed while subjects were standing. Nonparametric statistical analyses included the chi(2) test of association for nominal data and the Mann-Whitney test for comparison of population medians. RESULTS: All women had urethral hypermobility and met our standard clinical criteria for retropubic urethropexy. Fifteen women had incomplete follow-up data and were excluded from final analysis. Fifty-nine of 74 women (80%) were objectively cured, and 15 women had persistent genuine stress incontinence. Women who were cured did not differ from those who were not cured in age, parity, menopausal status, maximum urethral closure pressure, Valsalva leak point pressure, maximum cystometric capacity, detrusor instability, or prolapse stage. Women with persistent genuine stress incontinence were more likely to have had previous pelvic operations (P =.01). There were no differences in any electromyographic parameters at rest, with urethral squeezing, or during bladder filling between the groups. Women who were objectively cured had larger MRV values with repetitive coughing (P =.05) and larger increases from resting MRV values (DeltaMRV) with repetitive coughing (P =.04). Twenty-seven of 30 women with MRV values > or =25 microV with repetitive coughing were cured (positive predictive value [PPV] = 90%; negative predictive value [NPV] = 32%), and 22 of 24 women with more than a 10-microV increase in resting MRV values with repetitive coughing (DeltaMRV > 10 microV) were cured (PPV = 92%; NPV = 29%). If women had both an MRV value > or =25 microV and a DeltaMRV value >10 microV, the PPV was 100%; however, the NPV remained at 30%. CONCLUSION: Women who were cured of genuine stress incontinence with Burch retropubic urethropexy procedures had better motor unit action potential activation with repetitive coughing than women with persistent genuine stress incontinence. Urethral electromyography may be used to assess the neuromuscular integrity of the striated urethral sphincter and to help predict which women will have successful retropubic urethropexy procedures.

Adult↗

PubMed2002

Computer-assisted evoked electromyography with stimulating surgical instruments for recurrent/external laryngeal nerve identification and preservation in thyroid and parathyroid operation.

BACKGROUND: The reported incidence of recurrent laryngeal nerve (RLN) palsy/paralysis in thyroid and parathyroid operation ranges from 2% to 13%. Injury to the external branch of the superior laryngeal nerve (EBSLN) is less clearly documented. We hypothesized that a novel evoked electromyography system using an audio warning alarm might be beneficial for detection and preservation of the RLN and EBSLN. METHODS: A total of 117 thyroid/parathyroid operations were performed using a nerve locator/monitor (Neurovision SE, RLN Systems Inc, Jefferson City, Mo). Dissection was performed using a stimulating hemostat with conduction to an endotracheal surface electrode. RESULTS: A total of 97 thyroidectomies (50 total, 47 lobectomies) and 20 parathyroidectomies (16 directed, 4 bilateral) were performed representing 176 RLN and 152 EBSLN at risk. Of 176 RLN, 161 were correctly identified by the nerve stimulator alarm including 2 nonrecurrent nerves. The cricothyroid space and the superior pole vessels were scanned to identify the EBSLN by observing for cricothyroideus contraction or an alarm. Fourteen of 152 (8.9%) cases of type 2 anatomy were suggested where meticulous dissection of superior pole vessels prevented EBSLN injury. CONCLUSIONS: Computer-assisted evoked electromyography with stimulating surgical instruments is a useful surgical tool. This technology may be especially useful in reoperation in dense scar tissue and preserving the EBSLN in thyroid operation.

Diagnosis, Computer-Assisted↗

PubMed2000

Back muscle fatigue in healthy men and women studied by electromyography spectral parameters and subjective ratings.

To obtain reference data for future studies of patients with low back pain, back muscle fatigue was studied by surface electromyography at L1 and L5 lumbar levels in 55 healthy subjects exerting 80% of maximal voluntary contraction of the back extensors in a sitting position. Reference data were the initial value and rate of decrease (slope) of the median frequency during the contraction. The aim was also to study the effects of contraction time, gender differences, electrode locations and correlations with torque, age and subjective ratings. Initial median frequency was 52 Hz +/- 7.5, with no difference between electrode locations; steeper slopes were found at L5 level (-0.44%/s +/- 0.25) than at L1 (-0.36%/s +/- 0.26). No right-left differences and no gender differences were found for these parameters. A correlation was observed between slope and initial median frequency, higher for men (r approximately -0.7) than for women (r approximately -0.5). Intersubject coefficient of variation for the slope was smallest for the longest (45 seconds) recording time (60-70%), but still much higher than for the initial median frequency (14%). The torque and the subjective ratings of fatigue showed no correlation with the electromyography variables. We conclude that the same reference values can be used for men and women. Owing to the large intersubject range of the slope, the clinical use of this variable may, however, be impeded.

Adult↗

PubMed1993

Electromyography and the study of sports movements: a review.

Within electromyography (EMG), a particular specialty has been developed wherein the aim is to use EMG for the study of muscular function and co-ordination. This area of research is usually called kinesiological EMG. The general aims of kinesiological EMG are to analyse the function and co-ordination of muscles in different movements and postures, in healthy subjects as well as in the disabled, in skilled actions as well as during training, in humans as well as in animals, under laboratory conditions as well as during daily or vocational activities. This is often done by a combination of electromyographical and kinesiological or biomechanical measurement techniques. Because there are over 400 skeletal muscles in the human body and both irregular and complex involvement of the muscles may occur in neuromuscular diseases and in voluntary occupational or sports movements, it is impossible to sample all of the muscles of the entire body during the performance of complex motor skills. In addition, the measurement of kinesiological EMG in sport and specific field circumstances, such as the track and/or soccer field, the alpine ski slope, the swimming pool and the ice rink, demands a specific technological and methodological approach, adaptable to both the field and the sport circumstances. Sport movement techniques and skills, training approaches and methods, ergonomic verification of the human-machine interaction have, amongst others, a highly specialized muscular activity in common. The knowledge of such muscular action in all its aspects, its evaluation and its feedback should allow for the optimization of movement, of sports materials, of training possibilities and, in the end, of sports performance. Drawing conclusions from a review of the EMG research of 32 sports, covering over 100 different complex skills, including methodological approaches, is an impossible task. We have attempted to set standards concerning the EMG methodology at the beginning of this review. Electromyography and sports is a vast area and a complete review is impossible, as information will be found scattered in many different journals, including those on the sports sciences, ergonomics, biomechanics, applied physiology, in different congress proceedings, and so on. Consequently, many important aspects and possibly important publications may have been omitted from this review.

Electromyography↗

PubMed2005

Can mechanical myotonometry or electromyography be used for the prediction of intramuscular pressure?

The aim of the study was to characterize the electromechanical properties of skeletal muscle during isometric loading as well as to assess the potential of estimating intramuscular pressure by electrical and mechanical methods. Simultaneous electromyography (EMG), mechanical myotonometry (MYO, frequency and decrement of decay) and intramuscular pressure (IMP) measurements were conducted at rest and during short-term and long-term isometric contractions in patients with chronic pain in the anterior leg or dorsal forearm. The EMG amplitude and MYO(freq) accounted significantly (24-73%, p < 0.0001) for the variations in the IMP under short-term isometric loading. The IMP, EMG and MYO(freq) increased linearly with the relative muscle load (r = 0.868-0.993, p < 0.05). Mean values of EMG amplitudes at the contraction levels of 75% and 100% maximum voluntary contraction (MVC) and MYO(freq) values at all contraction levels (0-100% MVC) were higher for subjects with pathological values of IMP than for those with IMP values in the normal range. Total changes in IMP and EMG amplitude during 1 min isometric contraction were linearly interrelated (r = 0.747, p < 0.0001). We conclude that both surface electromyography and myotonometry parameters are indicative of intramuscular pressure, but neither of these methods can be used alone to diagnose non-invasively chronic compartment syndrome with acceptable accuracy.

Adolescent↗