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PubMed1975

Electromyography of the detrusor muscle.

In order to diagnose and treat patients with micturitional disturbances it is necessary to obtain as much information as possible about the function of the lower urinary tract in each case. We studied 70 female patients with micturitional disturbances by monitoring pulse, respiration, intrinsic bladder pressure, urine flow rate and volume, and detrusor and sphincter electromyograms during a 2 to 4-hour period. As earlier investigators have shown, there are 2 types of detrusor electromyograms: low frequency and high frequency activity. The low frequency activity is random in nature and has definite patterns in disturbed bladder function. It is a useful diagnostic parameter and, when considered with the results of the sphincter electromyograms and pressure recordings, it provides much diagnostic information in this group of patients. The high frequency activity is similar to that of striated muscle.

Electromyography↗
PubMed2004

Electromyography and the immobile vocal fold.

Laryngeal EMG has become a useful tool for the otolaryngologist in the four decades since the pioneering work of Faaborg-Anderson and Buchtal. It is able to distinguish between mechanical limitation and denervation in an immobile vocal fold. In the paralyzed vocal fold, it can guide workup by pointing to the site of the lesion. In the hands of a circumspect clinician, it can provide clinically valuable information regarding prognosis. Useful application of laryngeal EMG must rest on the basic fact that it isa qualitative test. Because of factors like sampling error, interfering signal from neighboring muscles, difficulties in needle placement, and our in-complete understanding of reinnervation physiology, the boundary between sophisticated, subtle interpretation and overreading is particularly difficult to distinguish. EMG diagnosis is based on patterns of abnormalities over time and, like other tests, requires interpretation in a clinical context. As in any such undertaking, there is no substitute for good judgment and experience. The most important benefit of clinical use of laryngeal EMG may be that it has catalyzed and broadened interest in laryngeal neurophysiology in the same way that stroboscopy has focused attention on the structure and function of the vocal fold lamina propria. The continuing refinement of electrodiagnostic approaches to the larynx that has resulted, including quantitative, single-fiber. and vector laryngeal EMG, and evolving methods of nerve conduction testing will continue to yield important insights into mechanisms of neural control that are likely to drive developments in the treatment of vocal fold paralysis in the future.

Action Potentials↗
PubMed1999

Diagnosis of carpal tunnel syndrome. Ultrasound versus electromyography.

This article presents a new technique for diagnosing carpal tunnel syndrome using ultrasound. The ultrasound characteristics of the normal and abnormal median nerve are discussed in relation to carpal tunnel syndrome. The development of ultrasound as a new diagnostic modality for carpal tunnel syndrome is presented in a three-part study correlating the ultrasound measurements of the median nerve and electromyogram of the median nerve. A new algorithm for evaluating patients with carpal tunnel syndrome is presented.

Adult↗
PubMed1988

Diagnostic anorectal functional studies. Manometry, sphincter electromyography, and defecography.

Anorectal manometric and electromyographic studies assess anorectal and pelvic floor neuromuscular disorders and can help in the diagnosis and management of incontinence, prolapse, megarectum, and other functional anorectal disorders. These studies can assess preoperative and postoperative anorectal function and help in the differential diagnosis of anorectal disorders, and thus they assist the surgeon in carrying out rational therapy.

Anal Canal↗
PubMed1999

The importance of normalization in the interpretation of surface electromyography: a proof of principle.

OBJECTIVE: To demonstrate the errors in surface electromyogram (EMG) interpretation that can be made when the EMG signal is not normalized. DESIGN: A case study as a proof of principle. MAIN OUTCOME MEASURES: The EMG amplitude between the upper and lower portions of the rectus abdominis in one subject during a trunk curl when the EMG signal was normalized (expressed as a percentage of a maximum voluntary contraction) and the amplitude when the signal was expressed in raw, unnormalized arbitrary units or raw millivolts directly read from the instrumentation. RESULTS: Interpretation of the unnormalized EMG signal suggests that a large difference in neural activation of the upper and lower sections of the rectus abdominis is occurring. In this condition the average activity in the lower rectus is 60.9% of that in the upper portion. This interpretation is incorrect. When the EMG signal is normalized, the differences between the upper and lower segments are reduced. When normalized, the lower segment activity is equal to that of the upper segment. CONCLUSIONS: Because of the inherent EMG signal variability, clinical interpretation of surface EMG signals requires normalization of the signal for physiologic interpretation and for comparison between bilateral muscles and between the same muscle on different days and between different subjects.

Action Potentials↗
PubMed1995

Correlation of compound action potential and electromyography with facial muscle tension.

Functional electric stimulation is a new method for dynamic rehabilitation of paralyzed muscles. The output of such prosthetic devices needs to be modulated by some index of the muscle movement. In facial paralysis a measure of the muscle contractions of the normal contralateral side seems to be an appropriate input. In the rabbit, we simultaneously measured the compound action potential of the buccal branch of the facial nerve, the electromyogram of the zygomaticus major muscle, and the muscle twitch tension through strain gauge. The compound action potential, electromyogram, and strain gauge each had a sigmoidal relationship to stimulus intensity. The compound action potential peak-to-peak amplitude was found to have a linear correlation to the peak twitch tension of the corresponding facial muscle. The electromyogram response, although more variable, also had a linear correlation with muscle contraction. The possibility of predicting the contraction of facial muscles before they actually occur is discussed in the context of available and future functional electric rehabilitation models.

Action Potentials↗
PubMed2003

Lumbar muscle fatigue and recovery in patients with long-term low-back trouble--electromyography and health-related factors.

OBJECTIVE: The aim was to explore the validity and reliability of EMG for assessing lumbar muscle fatigue. DESIGN: Patients with long-term low-back trouble (n=57) were compared to a healthy reference group (n=55). Back muscle fatigue and recovery were studied in relation to health-related factors. BACKGROUND: EMG spectral variables are important tools in the assessment of patients with low-back trouble. The influence of disability on these variables needs further investigation. METHODS: EMG from the lower back muscles was recorded during a 45 s trunk extension at 80% of maximal voluntary contraction torque and during recovery. Disability was studied using questionnaires. RESULTS: The reliability was high for maximal voluntary contraction torque and EMG initial median frequency, lower for the median frequency slope, and insufficient for median frequency recovery half-time. The patients had lower maximal voluntary contraction torque, higher initial median frequency at L5 level, flatter slope, and longer recovery half-time than the healthy subjects did. However, for subjects with significantly negative slope, indicating fatigue, there was no significant difference in slope between patients and healthy subjects, while, for subjects without such fatigue, patients showed significantly flatter slopes at L5. The sensitivity/specificity of the test was 86%/78%. The most significant variables selected with logistic regression were maximal voluntary contraction torque and initial median frequency at L5. Patients without significantly negative slopes during contraction and/or not exponential-like EMG recovery scored worse on several items concerning disability and self-efficacy. CONCLUSIONS: EMG spectral variables in combination with torque might be used for classification. For patients with long-term low-back trouble, the ability to fatigue the lumbar muscles sufficiently to obtain a significantly negative slope during an 80% maximal voluntary contraction may be a sign of better functioning. RELEVANCE: The ability to fatigue the back muscles during a test requiring a high force output might be achieved with back muscle training focused on increasing strength and self-efficacy.

Adaptation, Physiological↗
PubMed2003

Biomechanics and electromyography of a cumulative lumbar disorder: response to static flexion.

OBJECTIVE: To assess the mechanical and neurological processes active in the development of a cumulative trauma disorder (CTD) associated with repetitive exposure to periods of static lumbar flexion. METHODS: The spine of the feline model was subjected to a series of three 10 min sessions of static lumbar flexion with each session followed by a 10 min rest. A 7 h rest period was implemented after the series of three flexion-rest sessions while monitoring viscoelastic (disks, ligaments, etc.) creep and multifidus EMG. A model was fitted to the experimental data from the flexion-rest period and the 7 h recovery period. RESULTS: The creep developed in each 10 min static flexion period did not fully recovery during the following 10 min rest, resulting in a large cumulative creep at the end of the flexion-rest period. The cumulative creep did not fully recover over the following 7 h rest period. A neuromuscular disorder consisting of reduced muscular activity superimposed by spasms during static flexion periods and hyperexcitability during the 7 h recovery was evident. Comparison of the data to previous tests of continuous static flexion for 20 min reveal that the neuromuscular disorder elicited by the series of three 10 min flexion-rest was substantially attenuated when compared to a single 20 min static flexion although the overall work time was 50% larger. CONCLUSIONS: Frequent rest periods are highly beneficial in attenuating the development of a CTD, yet not able to prevent it, as viscoelastic tissues residual creep accumulates and its recovery is of extremely long duration. RELEVANCE: The data provides direct biomechanical and physiological evidence that explain the development of a CTD due to prolonged exposure to static lumbar flexion as well as confirms the epidemiological data correlating such work conditions with substantial increase in symptoms of low back disorders. The benefit of frequent rest periods in attenuating the risk of such a disorder is validated as an effective intervention.

Animals↗
PubMed1998

Aberrant muscle activation in patients after resection of non-primary motor areas: demonstration by surface electromyography.

Two patients presented with a tumor involving mainly the supplementary motor area or the premotor cortex. Shortly after tumor resection, each developed transient impairment of voluntary movements. An electromyogram, with the skin electrodes placed over the muscles of the upper arms and forearms, demonstrated aberrant ipsilateral, contralateral or bilateral muscle activation during unilateral motor tasks in both patients. The bilateral activation was more prominent in the patient who had an intact dominant hemisphere. The present study suggests for the first time the importance of non-primary motor areas of the human brain in activating the proper set of muscles on the proper side of the body.

Adult↗
PubMed1979

Dynamic electromyography and decision-making for surgery in the upper extremity of patients with cerebral palsy.

Seventeen children with cerebral palsy were selected for improvement in upper extremity function. Each had normal or nearly normal intelligence; each hand had good or mildly impaired sensibility; each arm had relatively good placement. Electromyograms with wire electrodes were utilized to study the patterns of activity of the planned tendon transfers. Only muscles with isolated activity in grasp were utilized to transfer in hands with weak grasp. Only muscles with isolated activity in release were utilized to transfer in hands with poor release.

Adolescent↗