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PubMed2005

Electromyography characterization of stretch responses in hemiparetic stroke patients and their relationship with the Modified Ashworth scale.

OBJECTIVES: To determine the validity of the Modified Ashworth Scale as a measure of spasticity by determining its relationship to surface electromyography activity and contracture. DESIGN: A controlled study of hemiparetic stroke patients with spasticity. SETTING: A physiotherapy department in a secondary care hospital. SUBJECTS: Thirty-one stroke patients and 20 healthy volunteers. MAIN MEASURES: The resistance to passive movement around the knee and ankle of the affected and unaffected legs was rated using the Modified Ashworth Scale. Passive range of movement was measured with a goniometer. Surface electromyography recordings of four lower limb muscles were taken during passive stretches of the knee and ankle. RESULTS: Hemiparetic patients produced surface electromyography responses to stretch that were of greater amplitude (unaffected limbs: mean = 25.82 mV (43.85), affected limbs: mean = 24.77 mV (35.46)) than those of healthy volunteers (mean = 15.85 (29.96)). The affected muscles of hemiparetic patients were more likely to produce surface electromyography responses to stretch of a sustained duration (45% of cases) compared with unaffected limbs (24% of cases) and those of healthy volunteers (16% of cases). The Modified Ashworth Scale showed a positive correlation with the magnitude (p < 0.05) and duration (p < 0.001) of the surface electromyography response. High scores on the Modified Ashworth Scale were associated with contracture (p < 0.001). Contracted muscles produced significantly greater surface electromyography reflex responses compared with noncontracted muscles (p < 0.05). CONCLUSION: The Modified Ashworth Scale reflects spasticity in terms of surface electromyography stretch responses produced by passive movement, but the relationship of spasticity to contracture remains unclear.

Aged↗

PubMed1991

An experimental study on the laryngeal electromyography and visual observations in varying types of surgical injuries to the unilateral recurrent laryngeal nerve in the neck.

A series of varying types of surgical injuries to the recurrent laryngeal nerve, including half section, double crush, suture ligation, and complete section of the nerve, was investigated in dogs by correlating clinical and electromyographic findings. The state of recovery from palsy was evaluated by recording the electromyography from the affected laryngeal muscles as well as by observing the movements of the vocal cords. Six electromyography patterns were recorded from the affected muscles following injuries to the recurrent laryngeal nerve. There is a close relationship between the electromyography patterns and the types of nerve injuries. Within 3 months after injuries of the recurrent laryngeal nerve, the electromyography motor unit potentials in the involved intrinsic laryngeal muscles and vocal cord movements on the side of the nerve injury were back to normal in the groups of dogs in which the recurrent laryngeal nerves were partially sectioned and doubly crushed; the electromyography potentials and vocal cord motion on the affected side did not return to normal in the group of dogs in which the recurrent laryngeal nerves were permanently ligated with suture. In the group of dogs which had had a complete section of the recurrent laryngeal nerve, no recovery of both electromyography and vocal cord function on the affected side was observed 6 months after injury of the recurrent laryngeal nerve. This study showed that the frequency of the regenerated potentials recorded from the affected muscles is related to the types and degrees of injuries to the recurrent laryngeal nerve. Recovery from recurrent laryngeal nerve palsy is complete within 3 months after nerve impairment if over half of the nerve fibers of the impaired nerve are maintained intact without degeneration. Moreover, the period from onset to complete recovery from palsy was remarkably short, less than 2 months. The most appropriate time for the electromyography examination to evaluate the degrees of the nerve injury and to anticipate the prognosis of recurrent laryngeal nerve palsy was proposed.

Animals↗

PubMedDate not supplied

Electromyography of the external anal sphincter muscle during urodynamic testing in children with meningomyelocele.

In this study the correlation between the electromyographic examination of the external sphincter muscle and the urodynamic findings in patients with meningomyelocele was evaluated. Urodynamic testing, consisting of cystometry with bladder, urethral and abdominal pressure monitoring was performed with simultaneous electromyography of the external and sphincter muscle in 61 children, 29 boys and 32 girls, divided in groups according to age and to the level of lesion. Normal urodynamic studies were always correlated with normal external sphincter electromyography. In all patients with a high lesion and in 79% of all others detrusor hyperactivity was correlated with pathological sphincter electromyography. The clinical neurological level of the lesion was not correlated with the function of the detrusor-sphincter mechanism. In 29% of the patients examined with needle electromyography detrusor-sphincter dyssynergia was found, which is less than in most other published studies. And although dyssynergia is a risk factor for renal deterioration, the authors conclude that its effect on the ureter is less important than in subjects with normal perineal musculature, since 80% of the examined patients with meningomyelocele showed pathological sphincter electromyography. These findings thus show a significant correlation between electromyography of the external sphincter muscle and the urodynamic findings in meningomyelocele patients, and clearly demonstrate the importance of urodynamic testing with simultaneous external sphincter electromyography, in order to improve both diagnostic accuracy and reliability of follow-up and treatment.

Adolescent↗

PubMed1989

[An effect of the clenching speed on the method of calculating the biting force of patients by using electromyography].

The recovery of the masticatory function in patients with dentures was assessed by several indices such as masticatory efficiency, maximal biting force and electromyographic analysis. We have attempted to develop a new method of calculating the biting force of edentulous patients by using electromyography. The method has almost been established, but, depending on the clenching speed, there is a certain difference between the estimates obtained from this method and the biting force obtained from a force transducer. The purpose of this study is to clarify the effect of the clenching speed on the method of calculating the biting force by using electromyography. In 9 healthy subjects with normal dentitions, biting force and electromyograms were recorded simultaneously under 3 different clenching speed conditions. After the recording, the relation between the biting force and integrated electromyography was compared thoroughly. The effect of the clenching speed on the method of calculating the biting force by using electromyography was also investigated. The following results and conclusions were obtained: 1. At a slow clenching speed, a linear relation between the biting force and integrated electromyography was found. 2. At a medium clenching speed, the relation showed a slightly upward curvature as the biting force was increased and a slightly downward curvature as it was decreased. 3. At a fast clenching speed, the relation between the biting force and integrated electromyography showed an upward curvature as the biting force was increased, and a downward curvature as it was decreased. 4. At the slow and medium clenching speeds the estimates obtained from this method approximated the biting forces obtained from a force transducer. 5. At the fast clenching speed, the tendency was found that the estimates obtained from this method were higher than the biting force obtained from a force transducer. 6. When realizing this tendency, the method of calculating the biting force by using electromyography can be said to be clinically effective.

Bite Force↗

PubMed2005

Uterine electromyography characteristics for early diagnosis of mifepristone-induced preterm labor.

OBJECTIVE: Differentiating uterine contractions leading to preterm birth from ineffective uterine activity is difficult with current tools. Uterine electromyographic activity is recordable and consists of bursts (group of action potentials) characterized by characteristics that are different during pregnancy and labor. Our aim was to identify the chronology of the changes in uterine pressure and electromyographic characteristics during mifepristone-induced preterm labor in pregnant rats and to determine the earliest characteristic to change. METHODS: On day 17 of gestation, intrauterine catheter and electromyography electrodes were implanted in the uterus. On day 18, rats were allocated for treatment with mifepristone or placebo. Intrauterine pressure and electromyography integral activities and electromyography mean were calculated before treatment and 6, 12, 18, 20, 22, and 24 hours after treatment. After mathematical transformation, burst analysis was performed by using power density spectrum energy, peak amplitude, and frequency. RESULTS: As expected, delivery rate within 24 hours was higher in the mifepristone-treated group. Changes in electromyography integral activity and mean, power density spectrum energy, and intrauterine pressure integral activity occurred late during preterm labor, in a range of 2-4 hours before delivery. Electromyography peak frequency of the power density spectrum exhibited early changes, with a shift from low to high frequencies starting at 12 hours before delivery. CONCLUSION: Electromyography peak frequency of the power density spectrum from individual bursts was the first characteristic to change after antiprogestin treatment, preceding any change in intrauterine pressure, making it a potentially useful marker for the early diagnosis of preterm labor.

Abortifacient Agents, Steroidal↗

PubMed1990

Evaluation of flow electromyography in patients with benign prostatic hyperplasia.

Combined uroflowmetry and external sphincter electromyography studies were done both preoperatively and postoperatively in patients with benign prostatic hyperplasia. In 56 patients preoperative electromyography during voiding showed silent or markedly suppressed activity in 41 patients (73.2%), while the remaining 15 patients (27.8%) revealed active electromyography. In the postoperative studies, 12 patients revealed active electromyography even after the release of obstruction. The urine flow rate following operation was not drastically improved in the active electromyography group compared to the silent electromyography group. We suppose that long-term urethral obstruction with prostatic adenoma could influence the function of relaxation of the external sphincter muscle in some patients with benign prostatic hyperplasia.

Aged↗

PubMed1994

A preliminary study of the prognostic role of electromyography in laryngeal paralysis.

Confidence in the reliability of laryngeal electromyography to predict recovery is critical if this tool is to be used to select the type and timing of surgical intervention. The characteristics of electromyography of 14 patients with unilateral vocal fold paralysis were assessed to determine which factor or combination of factors would be most useful in determining prognosis. We examined the duration, amplitude, waveform morphology, root-mean-square, and time interval from onset to electromyography recording. The results supported the concept that electromyography recordings are valuable in determining prognosis if performed before 6 months and preferably within 6 weeks of onset of laryngeal paralysis. A positive prognosis for laryngeal recovery was indicated when the following electromyography features were present in the immobile vocal fold: (1) normal motor unit waveform morphology, (2) overall electromyography activity characterized by a root-mean-square value greater than 40 microV in any one task, and (3) no electrical silence during voluntary tasks. On the basis of this criteria our overall correct prognostic rate was 89%.

Electromyography↗

PubMed2005

Manual acupuncture for analgesia during electromyography: a pilot study.

OBJECTIVES: To evaluate the analgesic effect of acupuncture for needle electromyography and to validate a sham acupuncture needle. DESIGN: Randomized, double-blinded, controlled study. SETTING: University-based electrodiagnostics laboratory. PARTICIPANTS: Fifty-one subjects referred for electrodiagnostic evaluation. INTERVENTIONS: Before the electromyography examination, either real acupuncture needles or telescopic sham needles were applied. MAIN OUTCOME MEASURES: Visual analog scale of pain and unpleasantness after 3 muscles were examined with electromyography. Pretest pain was subtracted to give a measurement of pain attributable to the electromyography. Subjects were asked which needle they thought they had received. RESULTS: Twenty-six subjects were randomized to the treatment group and 25 to the sham group. Pain in the treatment group (-.96) was less than in the control group (9.68), but it was not statistically significant (P=.13). Post hoc analysis, excluding 5 subjects known to have been treated by the novice acupuncturist, showed a significant difference of 14.4mm (P=.02). The proportion of subjects who thought they received real needles in the acupuncture group (69%) did not differ from the proportion in the control group (48%) (P=.13). CONCLUSIONS: Acupuncture may represent an effective form of analgesia for electromyography. This is the first study to suggest independently the telescopic sham acupuncture needle as an effective control.

Acupuncture↗

PubMed1983

Supplementation of cystometrography with simultaneous perineal floor and rectus abdominis electromyography.

A total of 26 patients with symptomatic voiding dysfunction underwent cystometrography concomitant with simultaneous perineal floor and rectus abdominis electromyography. Of the patients 20 had well defined neurological pathological conditions. Cystometrography/perineal electromyography revealed detrusor hyperreflexia with appropriate sphincter relaxation in 8 patients, with vesicosphincter dyssynergia in 10 and with pseudo-dyssynergia in 2. Rectus electromyography in these patients did not reveal electromyographic activity during the filling and expulsion phases of the cystometrogram. However, the 6 neurologically normal patients were noted to have detrusor areflexia with nonrelaxation of the sphincter on urodynamic examination. These patients characteristically attempted to void by abdominal straining, resulting in a concomitant increase in rectus and perineal electromyography activity. We conclude that the addition of rectus electromyography to the standard urodynamic methodology can improve significantly the recognition of intravesical pressure elevation owing to voluntary contraction of the abdominal musculature.

Abdominal Muscles↗

PubMed1992

Predictive value of electromyography in diagnosis and prognosis of the hypotonic infant.

To investigate the diagnostic validity of electromyography in the hypotonic infant, 79 children aged 0 to 12 months, seen over a 20-year period, were studied retrospectively. The diagnoses using clinical, muscle biopsy, and laboratory characteristics were: 25 central hypotonia, 20 spinal muscular atrophy, 20 myopathy, four myotonic dystrophy, four benign congenital hypotonia, two congenital muscular dystrophy, two myasthenia gravis, one infantile inflammatory myopathy, and one arthrogryposis multiplex congenita. Using strict criteria, electromyography accurately predicted the final diagnosis in 65% of infants with spinal muscular atrophy and was consistent with the diagnosis in another 25%. In contrast, electromyography accurately predicted the final diagnosis in only 10% of infants with myopathy and was normal in 88% of infants with central hypotonia. In infants with spinal muscular atrophy, there was no difference in the predictive value of electromyography when performed in the newborn compared to older infants. Normal distal nerve conduction velocities in infants with spinal muscular atrophy may predict prognosis, since these infants had a longer survival. Electromyography thus has a high predictive value for infantile spinal muscular atrophy but not for myopathy.

Biopsy↗

PubMed1996

Paraspinal muscle hematoma after electromyography.

There have been few reports of complications related to electromyography. Needle examination of certain muscles is sometimes avoided in patients taking anticoagulant agents, although no clear guidelines have been established. We describe a patient who was not receiving an anticoagulant and developed a large paraspinal muscle hematoma after routine electromyography. Subsequently, all patients who underwent paraspinal muscle electromyography and were diagnosed with radiculopathy at our institution over a 14-month period were reviewed. From this group, 17 patients were identified who had also underwent MRI of the appropriate spinal levels within 1 week after the needle examination. These images were reviewed for evidence of paraspinal muscle hematomas. Four small hematomas were identified in four different patients. None of these were radiologically significant compared with the large hematoma described in the case report. Radiologically apparent paraspinal hematomas after electromyography are an unusual complication of needle examination and do not appear to have any clinical significance. Nevertheless, the presence of these lesions justifies caution when considering electromyography of paraspinal and other deeper muscles in anticoagulated patients.

Adult↗

PubMed2004

Determination of the changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue.

The purpose of this study was to determine changes in the hypoglossal nerve function after suspension laryngoscopy with needle electromyography of the tongue. This study also attempted to determine the possible relationship between the predictive factors of intubation difficulty by using the intubation difficulty scale, which was introduced by Adnet et al., duration of suspension laryngoscopy and changes in hypoglossal nerve function after suspension laryngoscopy. The study was performed on 39 patients who underwent suspension laryngoscopy for benign glottic pathology. Pre-operative airway assessment was evaluated by the intubation difficulty scale and the duration of suspension laryngoscopy was recorded. Needle electromyography of the tongue was performed three or four weeks after the suspension laryngoscopy. After needle electromyography of the tongue, increased polyphasia was found in 13 patients (33 per cent), bilaterally in three of them. The interference pattern was reduced in two of these 13 patients. There was no statistically significant difference in predictive factors of intubation difficulty and the duration of the operation between these 13 patients with increased polyphasia and the remaining 26 patients with completely normal electromyography findings. These findings show that, in spite of normal clinical tongue function, subclinical changes can be detected by needle electromyography of the tongue after suspension laryngoscopy.

Adolescent↗

PubMed1998

[Electromyography in myopathies].

Despite increasing importance of molecular genetics, electromyography has preserved its place as a valuable tool in the diagnostic procedure of myopathies. Conventional electromyography allows the assessment of spontaneous activity, motor unit action potentials and interference patterns. In myopathies, fibrillations and positive sharp waves can be found in the majority of the cases. Motor unit action potentials are of short duration, low amplitude and may show increased polyphasia and number of satellite potentials. The interference pattern may be of low amplitude and compact already at submaximal contraction. Compared to conventional electromyography, automatic interference pattern analysis provides quantitative results and has the higher sensitivity and specificity. Normal conventional or automatic electromyography does not exclude a myopathy. For diagnostic purposes, electromyography will be followed by muscle biopsy and DNA analysis in most of the cases.

Diagnosis, Differential↗

PubMed2001

Prognostic value of laryngeal electromyography in vocal fold paralysis.

OBJECTIVE: To analyze the value of electromyography in predicting recovery from acute neurogenic vocal fold paralysis. STUDY DESIGN: Prospective case series. SETTING: University-based hospital of otorhinolaryngology-head and neck surgery. PATIENTS: Ninety-eight patients (56 women, with a mean age of 62.2 years; 42 men, with a mean age of 39.8 years) with 111 paralyzed vocal folds. The causes were varied, with thyroid surgery (53 cases) and idiopathic palsy (18 cases) being the predominant factors. INTERVENTION: Prognostication was based on electromyography performed no earlier than 14 days after onset of palsy. Findings were classified as neurapraxy, axonotmesis, and neurotmesis. Prognosis is inherent in this classification, since neurapraxy is presumed to resolve completely within 8 to 12 weeks, whereas axonotmesis is most likely to be followed by impaired vocal fold mobility. MAIN OUTCOME MEASURES: Vocal fold mobility after 6 months. RESULTS: In 102 vocal folds, some palsy of various degree persisted after 6 months. Free mobility of the paralyzed vocal fold was restored in 9 cases. By means of laryngeal electromyography, defective recovery, defined as absence of completely free vocal fold mobility, was predicted correctly in 94.4% of cases (68/72). For complete recovery, prognosis was accurate in only 12.8% of cases (5/39). CONCLUSIONS: The detection of neural degeneration by laryngeal electromyography allows the prediction of poor functional outcome with sufficient reliability in an early phase of the disease process. Conversely, the absence of signs of degeneration does not imply that complete recovery is to be expected.

Adult↗

PubMed1997

Single potential analysis of corpus cavernosum electromyography for the assessment of erectile dysfunction: provocation, reproducibility and age dependence--findings in 36 healthy volunteers and 324 patients.

PURPOSE: Corpus cavernosum electromyography is a controversial method for assessing erectile failure. For its application as a diagnostic tool with clinical relevance, intra-individual stability of the parameters in independent recordings as well as information about provocation and age dependence are required. MATERIALS AND METHODS: We investigated reproducibility, provocation and age dependence of 11 parameters of single potential analysis of corpus cavernosum electromyography for 36 healthy volunteers in 2 independent recordings with surface electrodes using a visual evaluation technique. Recording 1 results were compared to findings for 324 men with erectile dysfunction. RESULTS: In healthy subjects all parameters varied extremely among individuals and they were poorly reproducible at repetition. The definition of a normal range as mean plus or minus 2.5 standard deviations did not result in useful diagnostic criteria for individual cases. Activity was not age dependent. Significant differences between healthy and impotent men as defined groups were found in provocation (overall maximum likelihood chi-square 15.5, dF = 2, p < 0.0005). CONCLUSIONS: Single potential analysis of corpus cavernosum electromyography seems to be appropriate for distinguishing potent volunteers from patients with erectile dysfunction. Provocation of slow cavernous electric activity seems to be a promising parameter that should be considered for ongoing studies. However, a high range of variation of findings even intra-individually does not currently qualify the method for routine clinical use. Further research will show whether different means of documentation or evaluation, that is corpus cavernosum electromyography pattern analysis at rest after audiovisual sexual stimulation, drug application or digital conversion of data, will lead to better results.

Adult↗

PubMed1987

A disposable anal plug electrode for pelvic floor/anal sphincter electromyography.

During the last year we developed a disposable anal plug electrode for pelvic floor/external anal sphincter electromyography. The electrode consists of 2 disposable silver chloride surface electrodes mounted on a trochlear-shaped sponge. Testing of the new electrode with simultaneous registration of external anal sphincter electromyography using a coaxial needle electrode showed synchronous electromyographic patterns. In clinical urodynamic studies, including 48 cystometry studies with anal sphincter electromyography and 48 pressure-flow electromyographic studies, the electrode provided technically good and reliable electromyograms. The electrode design secures good contact to the recording surface and a safe fixation of the electrode during recording. The compressibility of the electrode might circumvent the problem of possible detrusor reflex inhibition induced by conventional hard anal plug electrodes. We recommend this technique for anal sphincter electromyography, since it is simple, reliable and without discomfort, and it does not require sterilization of the electrode.

Adolescent↗

PubMed1996

Use of spontaneous electromyography during revision and complex total hip arthroplasty.

Intraoperative peripheral nerve injury is a serious potential complication of orthopaedic surgery and various intraoperative neurophysiologic monitoring techniques have been used to avoid this complication. Although somatosensory evoked potentials have been used effectively in spinal surgery, the efficacy of this technique has not been demonstrated in total hip arthroplasty. Spontaneous electromyography is a promising, alternative nerve monitoring technique. This technique was used in 44 consecutive revision and complex hip arthroplasty procedures. Five cases demonstrated sustained electromyography activity during surgery that subsided after retractors were removed and the limb brought into an anatomic position. In none of these five cases was there any evidence of clinical neurologic dysfunction after surgery. One patient developed causalgia without any motor deficit, but had no sustained electromyography activity during surgery. Spontaneous electromyography provides real-time monitoring of nerve function that allows immediate corrective action to be taken before nerve injury occurs.

Adolescent↗

PubMed2003

The significance of anode location for stimulus-evoked electromyography during iliosacral screw placement.

OBJECTIVES: To determine the effect of anode location on the current threshold required to provoke an electromyograph response during stimulus-evoked electromyography for iliosacral screw placement. DESIGN: Prospective cohort. SETTING: Level I trauma center. PATIENTS: Nineteen consecutive patients with 23 unstable posterior pelvic ring injuries treated with iliosacral screws. INTERVENTION: Iliosacral screws were inserted percutaneously over guidewires. Twenty-seven screws were inserted, all into the first sacral vertebrae. The guidewire was used as the cathode for constant-current, stimulus-evoked electromyography for all data collection. Stimulus-evoked electromyographs were obtained with the guidewire at four different stations: at the sacroiliac joint (station I), at the first sacral neuroforamen (station II), in the body of the sacrum (station III), and when the iliosacral screw was in final position over the guidewire (station IV). MAIN OUTCOME MEASURE: Stimulus-evoked electromyographs were obtained with the anode at four different locations for each of the implant stations. Location A had the anode adjacent to the percutaneous insertion site of the guidewire, location B at the ipsilateral anterior superior iliac spine, location C at the midline, and location D at the contralateral anterior superior iliac spine. RESULTS: Moving the anode from midline (location C) toward the entry point of the guidewire increased the current threshold required to provoke an EMG response as much as 67.1% (p < 0.05). Moving the anode from midline to the contralateral anterior superior iliac spine decreased thresholds as much as 3.4% (p > 0.05). In one case, anode placement close to the guidewire insertion site (locations A and B) failed to identify a potentially dangerous implant because current thresholds were >8 mA. With the anode at the midline, current thresholds were <8 mA, indicating unsafe guidewire position leading to redirection of the guidewire. CONCLUSION: The physical location of the anode during stimulus-evoked electromyography monitoring for iliosacral screw placement significantly changes the current thresholds required to provoke an electromyograph response. Current thresholds required to stimulate nerves increase as the anode is moved toward the stimulating electrode. Anode placement ipsilateral to the stimulating electrode may provide a false indication of safe guidewire placement. We recommend anode location at or beyond the midline for stimulus-evoked electromyography monitoring during iliosacral screw placement.

Adolescent↗