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PubMed1995

Electromyography: do the diagnostic ends justify the means?

BACKGROUND: Physicians are sometimes reluctant to refer patients for electrodiagnostic studies (electromyography with nerve conduction studies [EMG/NCS]) believing the test is too painful and of little benefit. METHODS: We performed two separate surveys on 126 and 100 consecutive patients referred to our laboratory to determine if EMG/NCS was beneficial to the referring physician and to compare the level of anxiety experienced by patients before the study with the pain actually experienced during the study. RESULTS: The electrodiagnosis was discordant from the referring diagnosis in 39% of the patients with an abnormal EMG/NCS. Pretest anxiety levels were low in 59% of the patients, medium in 27%, and high in 14%. After the tests, 82% of the patients said that the test was not as bad as expected, and was generally only mildly painful. Ninety-three responded that they would have the test performed again. CONCLUSIONS: EMG/NCS often suggest alternative diagnoses, and the actual pain experienced during an EMG/NCS study is significantly less than expected.

Adult↗
PubMed1996

Biofeedback effect on electromyography responses in patients with spinal cord injury.

OBJECTIVE: To determine if electromyography (EMG) biofeedback procedures using an operant conditioning paradigm could significantly increase voluntary EMG responses from the triceps muscles of long term cervical spinal cord injured individuals. DESIGN: Intervention study with before-after trial measurement with each subject as its own control. SETTING: University outpatient clinic. PARTICIPANTS: One hundred individuals with cervical spinal cord injuries C6 or higher that were greater than 1-year duration, and who had less than normal strength and recordable EMG activity from the triceps, and who had reached a plateau in return of function. The first 100 individuals meeting this criteria who presented sequentially for EMG testing and biofeedback were included. No subjects were deleted from the sample. INTERVENTION: Muscle strength and surface EMG recording during attempts at elbow extension were obtained. The EMG pretest data were derived from the highest average recorded voluntary EMG response from the triceps during elbow extension. One 45-minute treatment session of EMG biofeedback for the triceps in an operant conditioning paradigm was provided for each of the 100 subjects. Seventy-five subjects received an average of 3 additional biofeedback treatment sessions. The posttest EMG data were derived from EMG measurements of the triceps during attempts at elbow extension from the 45-minute biofeedback treatment session and from the last additional biofeedback treatment session in a similar manner to the pretest procedures. MAIN OUTCOME MEASURES: A significant increase in EMG activity occurred from the triceps (p < or = .001) after one biofeedback treatment session and further significant increases in EMG activity occurred after additional biofeedback treatment sessions (p < or = .001). Initial muscle strength and initial EMG levels were not determining factors for response to the biofeedback. CONCLUSIONS: The results suggest the efficacy of biofeedback for increasing voluntary EMG responses in long term spinal cord injury patients.

Adolescent↗
PubMed1998

Electrophysiologic evaluation of denervated muscles in incomplete paraplegia using macro electromyography.

OBJECTIVE: To evaluate denervated muscles in persons with incomplete paraplegia due to thoracolumbar spinal injury (TLSI) using macro electromyography in determining indications for functional electrical stimulation (FES). DESIGN: A randomized clinical trial and a criterion standard. SETTING: A department of orthopedic surgery in a university hospital. PATIENTS AND OTHER PARTICIPANTS: Eighteen patients with incomplete paraplegia, including 11 with TSLI, and 50 healthy adults. INTERVENTION: Area and amplitude of macro motor unit potential (macro MUP) were measured at the tibialis anterior, the vastus lateralis, and the vastus medialis. The normal limits of macro MUP parameters were defined based on values from healthy subjects. Abnormal denervated muscles were detected by macro EMG and conventional EMG in paralytic patients. The correlation between macro MUP parameter values and muscle forces of the tibialis anterior and quadriceps femoris induced by electrical stimulation was analyzed. MAIN OUTCOME MEASURES: The number of abnormal muscles, parameter values, and muscle force induced by electrical stimulation. RESULTS: Abnormal muscles were found only in the TLSI patients and 13 abnormal muscles were detected by macro EMG only. The abnormal muscles defined by macro EMG showed insufficient contraction induced by electrical stimulation. The increase of parameter value negatively correlated with the muscle force (tibialis anterior area r=-.797, amplitude r=-.866; quadriceps area r=-.866, amplitude r=-.893; p < .001). CONCLUSIONS: These results suggest that macro EMG is useful in detecting denervated muscles, in determining indications for FES, and in predicting FES effects before implantation of electrodes.

Adolescent↗
PubMed1997

The role of electromyography in neurology.

A review is given of the role of electromyography (EMG) for diagnosis, pathophysiological description and monitoring of patients with disorders of the peripheral nervous system. Various EMG methods are presented and their principal differences are discussed. The usefulness of these methods varies depending on the pathology to be studied. With modern quantitative methods for analysis, EMG has become more sensitive and accurate and is therefore an important part in the evaluation of the neurologic patient. EMG results are usually combined with findings from other neurophysiological investigations (neurography, evoked potentials), histochemistry, biochemistry and most importantly with the clinical signs to give as complete a picture of the condition as possible. The usefulness of EMG depends on a number of factors other than the quality of the investigation as such. These aspects are discussed briefly.

Electromyography↗
PubMed1976

Electromyography of the rectum and colon in Hirschsprung's disease.

The electromyographic activity of the large bowel was studied in patients suffering from aganglionic megacolon and in comparable normal infants and children, using of an intraluminal electrode. Graphs obtained in control children showed a basic electrical rhythm of 4-6 waves/min with bursts of high frequency spikes, 3-4/sec, superimposed on the top of the slow waves. The recordings in Hirschprung's disease showed an irregular basic electrical rhythm with waves of variable duration and no high frequency potentials, as long as the electrode was positioned in the aganglionic zone. As soon as the electrode was introduced further up into the normally innervated colon the graph became identical to that seen in the normal bowel. Intraluminal electromyography of the rectum and colon seems to be a suitable procedure to diagnose aganglionosis of the rectum and the extent of the lesion.

Child↗
PubMed1997

A comparison of anal endosonography with electromyography and manometry in high and intermediate anorectal anomalies.

Anal endosonography, electromyography (EMG) of the external anal sphincter (EAS), and manometry of the internal anal sphincter (IAS) were performed in 15 patients with anorectal anomalies (10 with high and five with intermediate anomalies), ranging in age from 8 to 18 years. The anal endosonographic findings were compared with those for the EMG of the EAS and manometry of the IAS. An image including the hyperechoic band that corresponds to the EAS was obtained in all 15 patients. However, the distribution of EAS image was inadequate in high anomalies. In four patients who showed in Kelly score of 5 or 6, good visualization of the EAS was obtained in both anal endosonography and EMG. An Image including the hypoechoic band that corresponds to the IAS was obtained in five patients with high anomalies and in one with intermediate anomalies. Therefore, even in patients with anomalies, at these levels the IAS could be ultrasonically detected. However, only one of these six patients exhibited an anorectal reflex. These results indicate that, for the EAS, the findings of anal endosonography correspond well with those of EMG, but that for the IAS, they do not correspond with those of manometry. At the time of surgery for anorectal anomalies care should taken to preserve the IAS, which can be detected by anal endosonography even in patients with high or intermediate anomalies.

Adolescent↗
PubMed2001

The motor unit and electromyography--the legacy of Derek Denny-Brown.

With the development of the concept of the motor unit and new recording instruments, single motor unit action potentials (MUAPs) were recorded in 1929 in man by Adrian and Bronk and in the experimental animal by Denny-Brown. Studies of MUAPs in patients with neuromuscular disease followed, and in 1938, Denny-Brown and Pennybacker laid the foundation for clinical electromyography (EMG). Action potentials of single contracting or spontaneously firing motor units, termed fasciculations, were recorded and separated from the action potentials of single denervated muscle fibers, termed fibrillations. Thus, it was possible to interpret muscle twitching and cramping by EMG and separate neurogenic from myopathic diseases. Since then, EMG and neuromuscular disease have expanded greatly providing greater diagnostic capability and therapeutic success.

Boston↗
PubMed2001

Electromyography of respiratory muscles in amyotrophic lateral sclerosis.

We reviewed the records of 52 amyotrophic lateral sclerosis (ALS) patients examined between 1995 and 2000 who had needle electromyography (EMG) of their respiratory muscles, including the diaphragm, at or near the time of their diagnosis. With respiratory function testing, patients with abnormal diaphragmatic EMG at diagnosis (Group 1, n=23) had significantly lower forced vital capacity (FVC), lower daytime arterial PO(2) and higher PCO(2) measurements (p<0.05) than patients with normal diaphragmatic EMG (Group 2, n=29). Twenty-eight percent of the patients without symptoms or signs of respiratory insufficiency at the time they were examined had an abnormal diaphragm EMG. Mean survival of Groups 1 and 2 were similar. However, sub-analysis of patients within each group, comparing those treated with non-invasive positive pressure ventilation (NIPPV) with those not treated, showed that treated patients in Group 1 (abnormal diaphragm EMG) survived significantly longer (p<0.05) than untreated patients. They also started NIPPV earlier than treated patients in Group 2. We conclude that respiratory muscle EMG was simply and safely performed on ALS patients at or around the time of diagnosis. The procedure can detect sub-clinical respiratory muscle dysfunction. The technique used for EMG of the respiratory muscles, its pitfalls and contraindications are also reviewed.

Aged↗
PubMed1988

Bethanechol supersensitivity test, rhabdosphincter electromyography and bulbocavernosus reflex latency in the diagnosis of neuropathic detrusor areflexia.

A total of 57 patients with neuropathic or nonneuropathic detrusor areflexia was studied with the bethanechol supersensitivity test, electromyography of the urethral rhabdosphincter and bulbocavernosus reflex latency. The sensitivity of these tests in detecting neuropathic areflexia was 90, 87.5 and 78.1 per cent, respectively, and the specificity was 95.6, 76 and 80 per cent, respectively. When all 3 tests were performed together the combined accuracy approached 100 per cent. These combined tests are useful in the diagnosis of patients with equivocal bladder neuropathic conditions and in those with subtle neurological lesions.

Adolescent↗
PubMed1984

Electromyography of the external urethral sphincter in patients with prostatic hyperplasia.

We analyzed quantitatively the action potential of external urethral sphincter muscles by electromyography in 9 patients with benign prostatic hyperplasia and in 13 patients without micturition disturbances. In patients with benign prostatic hyperplasia the motor unit potentials had a mean amplitude of 290 plus or minus 40 microV., duration 5.0 plus or minus 0.1 msec. and phases 3.9 plus or minus 0.1. The control group values were 310 plus or minus 20 microV., 5.5 plus or minus 0.1 msec. and 3.8 plus or minus 0.1, respectively. There was a significant difference in duration, which was probably due to the difference in age of the 2 groups. An inverse relationship between age and duration was proved in the patients examined.

Action Potentials↗
PubMed1982

Abdominal wall electromyography: a noninvasive technique to improve pediatric urodynamic accuracy.

Abdominal wall electromyography, using sticky surface patch electrodes placed on the rectus abdominus muscles, was used during noninvasive urodynamic studies in 60 children to detect straining. Straining, which usually was imperceptible to the examiner, occurred in 64 per cent of neurologically normal children. Urodynamics identified detrusor-sphincter dyssynergia during straining to void but reverted to normal when the same children voided without straining. Because the urodynamic findings that characterize detrusor-sphincter dyssynergia are mimicked by straining and other common urologic entities, the potential for misdiagnosis is great unless some assessment of intra-abdominal pressure is made during neurourologic testing.

Abdominal Muscles↗
PubMed1979

The value of sphincter electromyography in urodynamics.

Multichannel urodynamic evaluation combined with sphincter electromyography was done on 102 patients. Normal and abnormal activity was defined. When detrusor hyperreflexia occurred in patients with obstruction, idiopathic detrusor hyperreflexia and upper motor neuron disease there was a reflex relaxation of the pelvic floor in 52 per cent of the cases. Electromyographic evidence of dyssynergia was associated with other evidence of sphincter obstruction in 50 per cent of the patients who voided by detrusor contraction and in 9 per cent of the patients who voided by Valsalva's maneuver. A diagnosis of dyssynergia should not be made from the electromyographic evidence alone, especially if the patient strains to void.

Anal Canal↗
PubMed1979

Pediatric urodynamics: a clinical comparison of surface versus needle pelvic floor/external sphincter electromyography.

Urodynamic evaluations were done on 37 children to diagnose voiding pattern abnormalities and/or recurrent urinary infections. Each of 25 children had 2 sets of testing to judge a practical method of urodynamic evaluation. Bipolar anal skin electrodes were compared to bipolar perianal muscle needle electrodes as a means of monitoring the urethral sphincter/pelvic floow electromyographic activity. In addition, the urethral catheter was compared to the suprapubic catheter as a means of monitoring intravesical pressure. The results were similar and statistically significant (p less than 0.001). The remaining 12 children were evaluated based only on the results of bipolar anal skin electrodes and uroflowmetry. The results of both groups clearly demonstrated that surface perianal electrodes are practical, accurate and reliable for the diagnosis and treatment of children with voiding pattern abnormalities. We recommend the use of surface electrodes and a urethral catheter as techniques for the urodynamic evaluation of voiding pattern abnormalities of children without overt neuropathology or extensive urethral operation. Preoperative surface electromyography of the urinary sphincters may prove to be a useful screening test to detect occult dyssynergia in patients who have had failed ureteral reimplants.

Adolescent↗
PubMed1976

Combined cystometry and perineal electromyography in the diagnosis and treatment of neurogenic urinary incontinence.

Function of the bladder and periurethral striated muscle was determined simultaneously by combined cystometry and electromyography studies in 120 patients. The coordinated tests were extremely helpful in identifying the different types of periurethral striated muscle activity in neurogenic bladder dysfunction, diagnosing the mechanism of incontinence and determining the appropriate therapy.

Adolescent↗
PubMed2001

Smooth muscle electromyography.

This article addresses smooth muscle physiology, electromechanical and pharmacomechanical coupling, computed-based interpretations, and the role of electromyography in the diagnosis of erectile dysfunction.

Discriminant Analysis↗
PubMed1986

Electromyography of urethral sphincter in women with urinary retention.

Concentric-needle electromyography (EMG) of the urethral sphincter muscle was carried out in 48 women with urinary retention. Changes in motor unit configuration indicating reinnervation were found in 16 women, and myotonic-like EMG activity, which may impair urethral relaxation, in 19 women. Sphincter EMG was normal in 13 cases. The finding of a significant abnormality in 72% of cases calls into question the validity of the commonly applied diagnosis of psychogenic urinary retention.

Electromyography↗
PubMedDate not supplied

Cervical flexion: a study of dynamic surface electromyography and range of motion.

BACKGROUND: In the comprehensive assessment of painful conditions, dynamic surface electromyography (sEMG) and range of motion (ROM) recordings can provide information regarding muscle spasm, antalgic postures, fear of pain (protective guarding), muscle injury, and disordered movement caused by pain. This study examines ROM and sEMG patterns observed during cervical flexion. OBJECTIVE: To demonstrate 2 distinctive sEMG recruitment and dynamic ROM patterns observed during cervical flexion and return to mid-line. DESIGN: Single-subject design with independent measurement of dynamic ROM and sEMG. SETTING: Applied clinical setting. PARTICIPANTS: Two subjects with normal ROM and cervical muscles were studied. MAIN OUTCOME MEASURE: One subject was studied with sEMG. looking at the cervical paraspinals and sternocleidomastoid muscles; the other subject was studied with an active ROM device. Three cervical movements were studied: lower cervical flexion, atlantoaxial (upper) cervical flexion, and a combination upper/lower cervical flexion. RESULTS: The active ROM device indicates larger movements (higher degrees of flexion) for the lower cervical flexion compared with upper flexion. The combined movement indicates a differential movement from 2 spinal segments. The sEMG recordings indicated differential recruitment patterns. The sternocleidomastoid recruits briskly during the flexion phase of the upper cervical flexion movement, whereas the cervical paraspinals recruit briskly during return to mid-line when the lower cervical flexion is used. The combined upper then lower cervical flexion movement recruits both sets of muscles. CONCLUSIONS: The results of the study indicate 2 distinct movement patterns associated with upper versus lower cervical flexion and 2 distinct sEMG recruitment patterns. The study suggests that these 2 distinct movements involve 2 distinct cervical segments and are associated with recruitment of different muscle groups. Applied clinical research on the cervical spine should use sEMG recordings to assess both the upper and lower flexion movements as the standard for the study of cervical flexion.

Adult↗
PubMedDate not supplied

The influence of a chiropractic manipulation on lumbar kinematics and electromyography during simple and complex tasks: a case study.

OBJECTIVE: To investigate whether a more sophisticated and detailed analysis of both simple and complex tasks may yield more information regarding the short-term influence of an adjustment on spine biomechanics. METHODS: The study used a single-subject, before-after design. Three-dimensional spine kinematics and trunk muscle electromyography were assessed during a variety of tasks performed by a professional golfer exhibiting non-specific, chronic, low back pain. The patient received a right-to-left and left-to-right spinous pull adjustment. RESULTS: After the adjustment, changes were seen in all 3 axes of motion during a golf swing, with concomitant muscle responses. In addition, changes in the off axes of motion were seen during simple movement tasks. CONCLUSIONS: A more detailed spine kinematic analysis, specifically analysis of motion in the nonprincipled axes, yielded more information regarding the short-term influence of an adjustment on lumbar spine motion and muscle function.

Adult↗