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PubMed2006

Focal canine tetanus: diagnostic value of electromyography.

A four-year-old, male Italian hound was presented with severe spasticity of both thoracic limbs that worsened with external stimuli. The remainder of the neurological and general physical examination was normal. Complete blood cell count, chemistry profile, and serology for protozoal diseases were within normal limits. Survey radiography of the cervicothoracic spine and abdominal ultrasonography showed no abnormalities. Electromyography of the thoracic limbs demonstrated the presence of "doublets" and simultaneous activity in both agonist and antagonist muscles. These abnormalities may be explained by a defective glycinergic inhibition at the spinal cord level. Together with the history, progression of signs, and clinical findings, electromyography supported a presumptive diagnosis of focal tetanus. The dog received tetanus antitoxin and antibiotic treatment and gradually improved over four months.

Animals↗

PubMed1992

Utility of a combined test of anorectal manometry, electromyography, and sensation in determining the mechanism of 'idiopathic' faecal incontinence.

Combined tests of anorectal manometry, sphincter electromyography and rectal sensation were carried out in 302 patients with faecal incontinence (235 women, 67 men). The results obtained were compared with 65 normal subjects (35 women, 30 men). A mechanism for incontinence was identified in all and the majority of patients had more than one abnormality. Two hundred and seventy eight patients (92%) had a weak external anal sphincter, 185 of these (67%, mostly women) also showed abnormal perineal descent, and 14 women showed clinical evidence of sphincter damage as a result of obstetric trauma. Ten per cent of patients with impaired external anal sphincter contraction showed associated evidence of spinal disease (impaired rectal sensation plus attenuated or enhanced reflex external anal sphincter activity). Unlike the other groups, the 'spinal' group contained equal numbers of men and women. Ninety seven patients (32%) had evidence of a weak internal anal sphincter. The external sphincter was also very weak and 92% of these patients also had perineal descent. Eighty two patients (27%) showed an unstable internal sphincter, characterised by prolonged 'spontaneous' anal relaxation under resting conditions and an abnormal reduction in anal pressure after conscious contraction of the sphincter or an increase in intraabdominal pressure. One hundred and forty two patients (47%) had a hypersensitive rectum associated with enhanced anorectal responses to rectal distension. All these patients had an abnormally weak external sphincter, suggesting that the hypersensitive or 'irritable' rectum should not be regarded as a cause of faecal incontinence unless accompanied by external sphincter weakness. Twenty four patients (8%) showed a normal basal and squeeze pressures and impaired rectal sensation; six showed giant rectal contractions during rectal distension. The results show that idiopathic faecal incontinence is not caused by a single abnormality, and it is suggested that combined anorectal manometry, electromyography, and sensory testing is a useful technique to identify the causes of faecal incontinence and provide a basis for appropriate treatment.

Adolescent↗

PubMed1974

Neuromuscular transmission in myasthenia gravis studied with single fibre electromyography.

Patients with myasthenia gravis have been investigated with single fibre electromyography. In all myasthenic muscles recordings were obtained where there was an increase of the jitter and occasional blocking of different degree of single fibre action potentials. The jitter is the variability at consecutive discharges in the time interval between action potentials from two muscle fibres from the same motor unit. During prolonged activity the jitter increased and blockings occurred more and more frequently. The size of the jitter and the degree of blocking also depended on the discharge rate. At a low rate the jitter was lower and the degree of blocking less than at the high rate. Injection of edrophonium could decrease or increase the jitter or leave it unaffected. Single fibre electromyography is a sensitive way of studying the transmission in individual motor end-plates in myasthenia gravis and is also a valuable diagnostic aid.

Action Potentials↗

PubMed1983

The use of conventional electromyography to assess external sphincter neuropathy in man.

Conventional electromyography was used to measure motor unit potential duration in the external anal sphincter in normal subjects and patients with idiopathic faecal incontinence. The results revealed a direct correlation between age and mean motor unit potential duration in control subjects, but no differences between age-matched male and female subjects. Patients with faecal incontinence exhibited prolongation of mean motor unit potential duration compared with matched controls. This technique provided useful quantitative data on reinnervation within the anal sphincter, complementing the results of single fibre electromyography.

Action Potentials↗

PubMed1978

Air cystometrography and sphincter electromyography in patients with bladder outlet obstruction.

38 patients with infravesical obstruction secondary to benign prostatic hypertrophy had CO2 cystometrography (CMG) and sphincter electromyography (EMG) at onset of retension and 6 weeks after intermittent bladder drainage. Neurological diseases were excluded in these patients. Three patterns of CMG tracings were obtained and were called, normal, 'compensating' and 'decompensating' on the basis of the volume: pressure ratio of the curves. By strict definition, no abnormal detrusor contractions were seen in any of these patients who also all had normal sphincter electromyography. It is questionable therefore if infravesical obstruction, in the absence of neurological deficits can account for the uninhibited detrusor contractions described in the literature. Rather it is possible to explain the above CMG tracings on the effects of obstruction on the bladder smooth muscle and collagen fibers which have been shown to be non-neural dependent.

Aged↗

PubMed1994

Penile electromyography in the diagnosis of impotence.

Cavernous electromyography of the flaccid penis was done in 93 impotent patients that were evaluated with several types of electrodes. We found that the potentials are generated by the cavernous tissue and are not the reflections of distant electromyographic events. Using monopolar needle electrodes, accurate interpretation of the electromyographic tracings seems possible. Our results confirm the value of penile electromyography as a way to objectivate penile smooth muscle atrophy as well as pelvic autonomic neuropathy with subsequent penile smooth muscle desynchronization. A neuromuscular dysfunction may be the causative factor in 39% of our impotent patients.

Electrodes↗

PubMed2001

Laryngeal reinnervation with the hypoglossal nerve. I. Physiology, histochemistry, electromyography, and retrograde labeling in a canine model.

This study was performed to determine whether the hypoglossal nerve (cranial nerve XI [XII]) would serve as a useful donor for laryngeal reinnervation by anastomosis to the recurrent laryngeal nerve (RLN). Twenty hemilarynges in 10 dogs were studied prospectively after XII-RLN anastomosis (group A; n = 5), split XII-RLN anastomosis (group B; n = 3), XII-RLN anastomosis with a 2-cm interposition graft (group C; n = 2), no treatment (group D; n = 5), RLN section (group E; n = 2), or ansa cervicalis-RLN anastomosis (group F; n = 3). Spontaneous activity was observed monthly by infraglottic examination through permanent tracheostomies and was recorded by electromyography. Laryngeal adductory pressure and induced phonation were obtained by stimulating the RLN while passing a pressure transducer balloon or humidified air through the glottis. At sacrifice, the laryngeal muscles were stained for adenosine triphosphatase to determine the ratio of type I to type II fibers. Retrograde labeling of the brain stem was performed with horseradish peroxidase. Infraglottic examination at 6 months showed a full range of adductory motion in groups A and B during the swallow reflex, comparable with that in group D. Groups C and F showed good bulk and tone, but little spontaneous motion. Group E remained paralyzed. Stimulation of the transferred nerves caused more activity in groups A and B than in the other groups; groups C and F partially adducted at high levels. The laryngeal adductory pressure responses of groups A and B were similar to those of group D. The XII-reinnervated larynges were capable of producing normal induced phonation. Retrograde labeling of the RLN showed that the reinnervating axons originated only in the hypoglossal nucleus. Electromyography of the reinnervated adductor muscles confirmed spontaneous activity in the dogs (awake). Histochemical analysis confirmed slow-to-fast transformation of both the posterior and lateral cricoarytenoid muscles, indicating that significant reinnervation occurred. We conclude that the hypoglossal nerve functions well as a donor for adductory reinnervation of the larynx.

Actomyosin↗

PubMed2001

Lack of evoked laryngeal electromyography response in patients with a clinical diagnosis of vocal cord paralysis.

There has been recent debate about whether patients with vocal cord immobility have a neurologic paralysis or whether synkinesis, the misdirection of axons to competing laryngeal muscles, is responsible for the lack of voluntary vocal cord motion. This issue was studied in 15 patients with vocal cord paralysis who underwent laryngeal reinnervation. Evoked electromyography was performed with a surface electrode endotracheal tube. The recurrent laryngeal nerve (RLN) was identified and stimulated with constant current. Of the 15 patients, only 1 produced a compound muscle action potential upon nerve stimulation. The remaining 14 patients had no evoked response during RLN stimulation. A control group of 8 patients with normal vocal cord mobility was studied, and each had a normal evoked electromyography response after RLN stimulation. These results support the assertion that patients who require treatment for vocal cord paralysis do not have synkinesis produced by RLN reinnervation.

Adult↗

PubMed1991

Laryngeal synkinesis following reinnervation in the rat. Neuroanatomic and physiologic study using retrograde fluorescent tracers and electromyography.

The functional organization of laryngeal motoneurons in the nucleus ambiguous (NA) was evaluated in adult male rats before and after recurrent laryngeal nerve section and reinnervation. Using retrograde double labeling techniques with fluorescent probes, we obtained the number and position of labeled neurons by using the Bioquant 3-D imaging system. Reinnervation was documented by electromyography. In nine control animals vector analysis revealed significant (p less than .05) separation of the posterior cricoarytenoid (PCA) muscle motoneurons and the thyroarytenoid and lateral cricoarytenoid (TA/LCA) muscle motoneurons. The PCA motoneurons were positioned ventromedially in the NA, and TA/LCA motoneurons were found dorsolaterally in the NA. Rostral-caudal separation was not significant. Electromyography revealed phasic electrical activity synchronous with respiration in the PCA, and activity synchronous with deglutition in the TA/LCA. In four animals surviving 15 weeks following recurrent laryngeal nerve section and primary neurorrhaphy, functional organization within the NA was lost and phasic motor unit activity synchronous with respiration was seen in the TA/LCA muscle as well as the PCA. Vector analysis revealed the reinnervating motoneurons for both the PCA and TA/LCA to be positioned dorsolaterally, similar to the control group TA/LCA motoneurons. These findings demonstrate a shift in the topographic organization of laryngeal motoneurons within the NA following reinnervation, with random organization occurring at the neurorrhaphy site.

Animals↗

PubMed1994

Limitations of electromyography and magnetic stimulation for assessing laryngeal muscle control.

The development of new phonosurgical techniques has increased the level of interest in the field of neurolaryngology. This field requires valid techniques for determining if muscle activation is normal. Laryngeal electromyography is being used more frequently to assess muscle innervation and synkinesis. Further, magnetic stimulation has been introduced as a noninvasive technique for nerve stimulation. Technical limitations that affect the clinical utility of both these techniques are reviewed: 1) difficulties obtaining selective and accurate electromyographic laryngeal muscle recordings, 2) normal variation in movement and muscle activation patterns within and between normal individuals when producing the same speech syllables, and 3) variation in laryngeal muscle response latencies between and within normal subjects during peripheral magnetic stimulation. Given the normal variation in laryngeal electromyography and magnetic stimulation response latencies, these techniques may not yet be reliable or accurate for assessing reinnervation or synkinesis following recurrent laryngeal nerve injury.

Adult↗

PubMed2007

Electromyography of the buccal musculature of octopus (Octopus bimaculoides): a test of the function of the muscle articulation in support and movement.

The buccal mass musculature of the octopus (Octopus bimaculoides) was studied with electromyography to test the predictions of a previous morphological study in which we suggested that the muscles of the buccal mass serve as both the effectors of movement and as the joint itself, forming a new category of flexible joint termed a ;muscle articulation'. The predictions of muscle function were tested by correlating muscle electrical activity in isolated buccal masses with spontaneous beak movements. Bipolar electromyography electrodes were implanted in the various beak muscles and beak position was recorded simultaneously with an electronic movement monitor (N=14). The results are consistent with the hypothesis that the lateral mandibular muscles produce opening movements of the beaks and provide the first definitive explanation of the opening mechanism. The results are also consistent with the hypothesis that the superior mandibular muscle functions primarily in closing. Co-contraction of the lateral mandibular muscles and the superior mandibular muscles was also observed, suggesting that these muscles may also stabilize the beaks during movement or provide a means of controlling the location of the pivot between the beaks. This study provides an important first test of the predictions of the role of the complex musculature found in muscle articulations such as the cephalopod buccal mass.

Animals↗

PubMed2001

Evaluation of a signal-adapted filter for processing of periodic electromyography signals in horses walking on a treadmill.

OBJECTIVE: To evaluate an adaptive-filter method for use in analysis of periodic electromyography (EMG) signals in which the transfer function of the filter is matched to characteristics of the signal. ANIMALS: 15 adult horses without clinical signs of back pain. PROCEDURE: Electromyography signals of the left and right longissimus dorsi muscles, middle gluteal muscles, and triceps brachii muscle were recorded from horses walking on a treadmill, using bilaterally placed surface electrodes. A reflective marker was placed on the hoof of the left hind limb for simultaneous kinematic measurement of motion cycles. Absolute value of the measured EMG signal was convoluted by use of a filter signal equivalent to the length of 3 motion cycles. The signal-to-noise ratio (SNR) was calculated from the autocorrelation function and compared with the SNR of the unfiltered and the low-pass filtered signals. RESULTS: The signal-adapted filter significantly increased SNR (by 7.3 dB, compared with the low-pass filter, and by 11.1 dB, compared with the unfiltered EMG signal). CONCLUSIONS AND CLINICAL RELEVANCE: The signal-adapted filter eliminates signal parts that are not correlated to periodic motion. The method reported here improves the applicability of periodic EMG signals as a clinical tool.

Animals↗

PubMedDate not supplied

Clinical nerve conduction and needle electromyography studies.

The electrodiagnostic study, consisting of nerve conduction studies and needle electromyography, is a useful adjunct to the clinical examination of the peripheral nervous system. The three types of nerve conduction study are motor, sensory, and mixed, of which motor is the least sensitive. Electromyography records the intrinsic electrical activity of muscle fibers, thus providing the physiologic status of muscle function. To interpret the electrodiagnostic study results, the clinician must understand the anatomic and physiologic basis of the studies. Peripheral nerve entrapment initially results in focal demyelination; thus, nerve conduction velocity slows across the site. However, with radiculopathy and nerve root compression, the nerve conduction study may be normal. Both nerve trauma and polyneuropathy show marked differences in their effect on the results of electrodiagnostic studies.

Action Potentials↗

PubMed1999

[Treatment of hemifacial spasm with type A botulinum toxin (AGN 191622): a dose finding study and the evaluation of clinical effect with electromyography].

Forty-one patients with hemifacial spasm had an injection of type A botulinum toxin (AGN 191622; Allergan Co. Ltd., Irvine, CA). Patients were randomly divided into 3 groups by the injection dose: group L (1 unit; 14 patients), group M (5 units; 14 patients), and group H (10 units; 13 patients). Half of the dose was injected into the orbicularis oculi and the rest into the zygomaticus major muscles on the affected side. The clinical effect and electromyogram were evaluated at 2 weeks after the injection. The clinical benefit was dependent on the injection dose, and group H showed the highest rate of improvement (84.6%). No adverse effect related to the toxin was demonstrated except one patient in group H who showed mild and transient lagophthalmos. For 81.8% of group H patients, the final judgement was "useful" or "very useful", which was 9.1% for group L and 50.0% for group M. On the other hand, electromyography disclosed no consistent dose-finding relationship. We conclude that at least 10 (preferably more) units of botulinum toxin are necessary for effectively treating hemifacial spasm. Electromyography has only limited value for the evaluation of clinical effect.

Botulinum Toxins, Type A↗

PubMed1976

[Continuing registration of muscle temperature during electromyography].

Measurements of muscle temperature were performed during and after contractions of human skeletal muscle using an electromyography-needle-electrode, which contains a thermo-element. The investigations aimed at explaining a drop in temperature during contraction, earlier described, and getting some aspects of possible employment of temperature measurements carried out simultaneously with electromyography. 1. The course of temperature during contraction (increase or decrease) depends on the heat of contraction, blood flow through muscle, penetration depth of the thermoelement, gradient of temperature and efficacy of a compression of blood vessels. It results from a superimposition of the single effects. 2. A decrease in temperature in various extremity muscles during contraction is explained by a compression of blood vessles caused by the shortening of muscle, as described earlier by other authors. 3. The interpretation of temperature curves, especially the quantitative interpretation, becomes very uncertain because of various sources of error. A differentiation between muscle heat and influence of blood flow is not sufficiently possible. 4. Nevertheless measurements carried out under conditions of disturbed blood supply, myopathies and polyneuropathies consistent with experiments performed during cooling and warming muscle in a water-bath, causing a reactive hyperemia or a defective circulation by using a blood pressure instrument show that changes in blood circulation are expressed by changes in temperature curves. Measurements carried out simultaneously on agonists and antagonists show satisfactorily the contrary changes in blood circulation known from the literature.

Adult↗

PubMed2000

Dysesthetic vulvodynia. Long-term follow-up after treatment with surface electromyography-assisted pelvic floor muscle rehabilitation.

OBJECTIVE: To determine the long-term follow-up status of dysesthetic vulvodynia patients who were asymptomatic at the termination of treatment using surface electromyography (sEMG)-assisted pelvic floor muscle rehabilitation. STUDY DESIGN: A chart review of the years 1994-1996 identified 62 patients with a diagnosis of dysesthetic vulvodynia on initial evaluation and who were asymptomatic at the termination of treatment. Forty-three of these patients responded to a survey requesting information on their pain, maintenance activities and treatments, daily functioning and sexual status since treatment termination. RESULTS: Thirty-eight of the 43 patients (88.4%) reported experiencing no vulvar pain since completion of treatment. Three patients reported a single episode of pain, and two patients reported two episodes each. All five of these patients reported the absence of any vulvar pain for a mean period of 19.8 months prior to completion of the survey. One hundred percent of the 43 dysesthetic vulvodynia patients studied reported being pain free a mean of 39.5 months after successful treatment termination. No vulvar pain-related treatments or significant restrictions on daily activities were reported. All patients reported sexual interest, pleasure and activity. CONCLUSION: Surface electromyography-assisted pelvic floor muscle rehabilitation is an effective and long-term cure for dysesthetic vulvodynia.

Electromyography↗

PubMed1999

Electromyography in craniomaxillofacial trauma.

BACKGROUND AND PURPOSE: Electromyography is used in conjunction with clinical diagnosis to determine the presence and extent of craniofacial injuries; it is also an aid in prognosis of recovery. This article reviews the neural pathophysiology following trauma and the basic principles of electrodiagnostic testing; such understanding helps to determine indications for electrodiagnostic testing. METHODS AND MATERIALS: Electrodiagnostic techniques can detect and differentiate the degree of injury. There are three major categories of nerve injury--neurapraxia, axonotmesis, and neurotmesis. In neuropraxic injuries, stimulation distal to the lesion will continue to elicit a response indefinitely; in more severe injuries, axonal degeneration begins within 3 to 5 days postinjury. RESULTS AND/OR CONCLUSIONS: Electromyography may be used as a valuable adjunct to traditional forms of diagnosis and prognosis. The accuracy of electrodiagnostic data reported in the literature ranges from 50% to 67% in some studies and 77% to 90% in others. Studies with larger patient populations and longer follow-up periods are required.

Action Potentials↗

PubMed1975

[Electromyography and electroneurography in peripheral facial nerve paralysis (author's transl)].

The function of the facial nerve can be examined by 4 electrodiagnostic methods. In the nerve excitability test and electroneurography the facial nerve itself is stimulated over the stylomastoid foramen, whereas chronaximetry and electromyography are performed in the muscles. In the majority of patients with Bell's palsy it is possible to make a more or less favourable prognosis by clinical examination alone. As soon as the paralysis is evident only these diagnostic tests give an accurate prediciton. The early realisation of a poor prognosis is surgically important. Chronaximetry and electromyography do not facilitate early assessment of the prognosis. The nerve excitability test and electroneurography can assist in the prognosis within the first 6 days after the onset. This is especially so with electroneurography, in which the muscle action potentials are examined during facial stimulation. A continual decrease of amplitude of the action potential of 50% in 2 days and a complete loss of potential in 4 to 6 days indicate a total nerve degeneration with an unfavourable prognosis.

Action Potentials↗