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PubMed2003

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation.

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

Adolescent↗

PubMed2005

Primary bladder neck dysfunction in children and adolescents I: pelvic floor electromyography lag time--a new noninvasive method to screen for and monitor therapeutic response.

PURPOSE: One of the key findings for making the diagnosis of primary bladder neck dysfunction (PBND) on videourodynamics (VUDS) is prolongation of the time between the start of a voluntary detrusor contraction and the start of urine flow (opening time). Since normally this dynamic event is immediately preceded by pelvic floor relaxation, we determined if the interval between pelvic floor relaxation on pelvic floor electromyography (EMG) and the start of flow (pelvic floor EMG lag time), approximated opening time. MATERIALS AND METHODS: Opening time measured on VUDS and pelvic floor EMG lag time measured on noninvasive uroflowmetry/EMG were compared in 22 consecutive patients with a mean age of 13.8 years diagnosed with PBND and a control group of 17 normal children. In addition, 19 patients with PBND were placed on alpha-blocker therapy, and pretreatment and on treatment uroflowmetry and pelvic floor EMG lag time values were compared. RESULTS: Mean opening time and mean pelvic floor EMG lag time were statistically indistinguishable from each other in the PBND and normal groups (27.4 vs 23.9 and 1.1 vs 1.3 seconds, respectively, p >0.550), but they differed significantly between the normal and PBND groups (p <0.001). On alpha-blocker therapy a decrease in mean pelvic floor EMG lag time from 24.47 to 6.67 seconds (p <0.001) corresponded with improved flow parameters, while no improvement was noted in untreated patients. CONCLUSIONS: Pelvic floor EMG lag time directly correlates with opening time and, when prolonged and associated with abnormal uroflowmetry, it is highly suggestive of PBND, thereby, justifying more invasive evaluation with VUDS or the initiation of empirical drug therapy. Most importantly, it provides an objective means of monitoring treatment response in a disorder that often has lingering symptoms.

Adolescent↗

PubMed2005

Corpus cavernosum electromyography during morning naps in healthy volunteers: further evidence that corpus cavernosum potentials reflect sympathetically mediated activity.

PURPOSE: We assessed the practicability of corpus cavernosum (CC) electromyography (EMG) in volunteers during morning naps in the laboratory and further validated this method. MATERIALS AND METHODS: A total of 11 healthy volunteers with a mean age of 23.8 years (range 19 to 31) were included. CC-EMG was started between 6:30 a.m. and 7 a.m. Two surface electrodes were placed at the base of the penis bilaterally and a reference electrode was placed on 1 kneecap. A strain gauge or Barlow gauge (Behavioral Technology, Salt Lake City, Utah) was used to monitor changes in penile circumference. Subjects were asked to sleep. Recording duration was 2 to 3 hours. Two recordings were performed per subject. RESULTS: Full erection was observed on 17 of the 22 recordings (77%), partial erection was noted on 3 (14%) and no tumescence was observed on the other 2 (9%). CC potentials consistently disappeared during tumescence and erection, while continuous CC potential oscillations reappeared during detumescence. During flaccidity bursts of CC potentials and electrical silence were recorded. Penile shrinkage was observed to accompany CC potentials but not to accompany electrical silence. CONCLUSIONS: CC-EMG during morning naps is a practical and valid method for investigating CC electrophysiology. CC-EMG signal patterns during tumescence, detumescence and flaccidity fit the existing theory that CC potentials reflect cavernous smooth muscle sympathetically mediated activity.

Adult↗

PubMed2005

Surface electromyography of continuous drinking in healthy adults.

OBJECTIVES: To give a description of normal surface electromyography (sEMG) aspects of uninterrupted (continuous) drinking and to establish normal sEMG values for swallowing 100 mL of water. STUDY DESIGN: Prospective observational study of healthy volunteers. SUBJECTS: Four hundred twenty apparently healthy male and female volunteers divided into three age groups (18-40, 41-65, 66+ years). METHODS: The evaluated parameters included the total duration, number of swallows, amount of water per swallow, and voltage of the EMG activity of the orbicularis oris, masseter, and submental-submandibular muscles and the infrahyoid muscle groups covered by the m. platysma. RESULTS: The overall normal mean values for duration, number of swallows, and amplitude of muscle activity during continuous drinking were compiled. The age-related increase in duration of swallows and of total drinking time was significant only in the older group (95% confidence interval, P < .05). There were no significant sex-related differences for any age group (P > or = .05). The mean electric activity (in muV) varied insignificantly among the age groups. The activity of the m. orbicularis oris was the least informative. An unexpectedly significant number of healthy subjects (14.25%, P < .05) performed a dry swallow after drinking. CONCLUSION: The establishment of normal sEMG levels now makes this modality applicable for evaluating the swallowing mechanism among adults for potentially identifying and ruling out abnormalities. Its simplicity, noninvasiveness, and low level of discomfort also make it highly suitable for screening purposes.

Adolescent↗

PubMed2006

Diagnosis of unilateral recurrent laryngeal nerve paralysis: laryngeal electromyography, subjective rating scales, acoustic and aerodynamic measures.

OBJECTIVE/HYPOTHESIS: To determine whether specific laryngeal electromyography (LEMG) patterns in patients with unilateral vocal fold paralysis/paresis (UVFP) are related to etiology of injury, time from onset of injury, patient perception of symptom severity, acoustic measures, and laryngeal aerodynamic measures. STUDY DESIGN: This is a retrospective review of 75 patients. METHODS: Each patient received LEMG, acoustic and aerodynamic testing, and a subjective rating scale assessment (the Glottal Closure Index). Statistical analysis by groups were performed using both chi and single-factor analysis of variance testing. RESULTS: An iatrogenic etiology was associated with poor tone on LEMG (P = .05). Those individuals evaluated after 3 months after onset demonstrated more nascent units, a sign of reinnervation, compared with individuals evaluated before 3 months (P < .02). Individuals with fewer normal motor units on LEMG had significantly higher mean translaryngeal air flows (P = .044). Individuals with poor recruitment had significantly shorter maximum phonation times (P = .034) and higher mean flows (P = .044). Individuals with better laryngeal tone as noted on LEMG had significantly lower mean flows (P = .06). CONCLUSIONS: Specific LEMG patterns are related to the etiology of the UVFP and time course since recurrent laryngeal nerve injury. LEMG appears to reflect vocal fold muscle tone as seen on laryngeal function studies. In combination, these studies provide a cohesive assessment of laryngeal function in patients with UVFP.

Adult↗

PubMedDate not supplied

Diagnostic value of electromyography in children and adolescents.

The diagnostic accuracy in pediatric neurology has been considerably improved by new methods such as magnetic resonance imaging and molecular genetic analysis. However, standard diagnostic techniques continue to play an important role. The authors analyzed the diagnostic value of electromyography (EMG) and nerve conduction studies (NCS) in a retrospective study of 498 pediatric patients. The overall consistency between EMG results and the final clinical diagnosis in all children examined was 98%. In myogenic diseases, the concordance between EMG and clinical findings was lower (80%), because some patients with congenital myopathies showed normal EMG findings in this group. Peripheral neurogenic diseases were in all but one of the cases diagnosed correctly (99.5%). No decrease in diagnostic reliability was found in the younger age group. EMG and NCS examinations have to be adapted to the needs of children by an experienced examiner, but continue to be valuable diagnostic methods in pediatric neurology.

Adolescent↗

PubMedDate not supplied

Electromyography of idiopathic toe walking.

Eighteen idiopathic toe walkers were evaluated by gait electromyography to define muscle timing abnormalities. This group was compared with a matched group of normal children walking on their toes and to a group of patients with cerebral palsy and equinus deformities. Although timing in all three groups differed from normal timing, the two patient groups showed some statistically significant differences in phasic timing from the control group. However, no significant differences existed between toe walking and spastic children. Historical data (family history, male predominance, and learning disabilities) suggest that idiopathic toe walking is a true entity, although the gait electromyograms were not diagnostic.

Adolescent↗

PubMed1994

NNERVE: neural network extraction of repetitive vectors for electromyography--Part II: Performance analysis.

We have presented a new method for the decomposition of clinical electromyographic signals, NNERVE, which utilizes a novel "pseudo-unsupervised" neural network approach to signal decomposition. In this paper, we present a detailed performance analysis. We present definitions for quantitative performance criteria. NNERVE is shown to be highly reliable over a wide range of neural network architectures. It is also minimally sensitive to learning parameters. The degradations of performance over a wide range of signals and parameters are shown to be gradual, slight and graceful. These characteristics are shown to translate directly into a high degree of robustness over widely varying signals. Real signals obtained from the entire range of patients encountered in clinical situations are shown to be correctly handled without any modifications or adjustments of any parameters. This neural network method is then directly compared to a prior traditional signal processing method and is shown quantitatively to have consistently superior performance on both simulated and real signals. Clinically acceptable performance over a wide range of signals, recorded using standard clinical methodology, and the lack of a need for user interaction, will facilitate the use of motor unit quantitation in routine clinical electromyography.

Algorithms↗

PubMed2004

Improved maximum frequency estimation with application to instantaneous mean frequency estimation of surface electromyography.

The purpose of this study was to improve the maximum-frequency estimation. Three methods to estimate the maximum frequency of a bandlimited signal with additive white noise were compared. Two existing methods, the threshold-crossing method (TCM) and the hybrid method, were modified for time-frequency representations. A novel approach, the running-block threshold method (RBTM), was introduced. Based on calculation of detection probability (sensitivity) the RBTM improved the maximum-frequency estimate as compared with the TCM. The maximum-frequency estimation methods were also used to determine the integration interval for instantaneous mean-frequency (IMNF) estimation from synthesized surface electromyography containing white noise. Results showed that the IMNF estimate was improved by using any of the three methods and that the RBTM gave the best IMNF estimate.

Action Potentials↗

PubMed2003

Wavelet analysis of surface electromyography to determine muscle fatigue.

Muscle fatigue is often a result of unhealthy work practice. It has been known for some time that there is a significant change in the spectrum of the electromyography (EMG) of the muscle when it is fatigued. Due to the very complex nature of this signal however, it has been difficult to use this information to reliably automate the process of fatigue onset determination. If such a process implementation were feasible, it could be used as an indicator to reduce the chances of work-place injury. This research report on the effectiveness of the wavelet transform applied to the EMG signal as a means of identifying muscle fatigue. We report that with the appropriate choice of wavelet functions and scaling factors, it is possible to achieve reliable discrimination of the fatigue phenomenon, appropriate to an automated fatigue identification system.

Algorithms↗

PubMed1989

Real-time signal acquisition and analysis for clinical dental electromyography using a microcomputer-based system.

The Electromyographic (EMG) Signal Acquisition and Analysis System is an integrated hardware and software system that digitizes multichannels of amplified EMG signals and stores them in user defined disc files before analysis. The software runs on all IBM PC and its compatibles with the appropriate analogue-to-digital (A/D) conversion board. Both time and frequency domain analyses can be computed on-line. This system provides a low cost method of digitizing and analysing EMG signals on real-time for clinical dental electromyography.

Adult↗

PubMed1991

Influence of an occlusal splint on integrated electromyography of the masseter muscles.

In order to examine the effect of an occlusal splint on the integrated electromyography (EMG) of the masticatory muscles, EMG of bilateral masseter muscles of 23 patients with temporomandibular joint disturbance syndrome (TMJDS), with and without an occlusal splint, was measured and integrated on line during maximum clenching. It was found that the integrated myoelectrical value of the masseter muscle on the involved and non-involved side was reduced with the occlusal splint. The absolute difference between integrated myoelectrical values in the left and right masseter muscles was reduced with an occlusal splint, but the relative difference remained virtually unchanged. These results indicate that the occlusal splint can decrease masseter muscle activity and thus exert a therapeutic effect.

Adult↗

PubMed1996

Evaluation of masticatory muscles of edentulous patients by computed tomography and electromyography.

On account of its tissue resolution capacity, computed tomography (CT) is an excellent method for the examination and quantitative analysis of the masticatory muscles. The aim of the present study was to evaluate the influence of the long edentulous period by CT on the structure of the main masticatory muscles in 10 edentulous patients and to study their functioning by electromyography (EMG) in connection with the renewal of the dentures. CT scanning was performed before prosthodontic treatment and EMG recordings of the masseter and temporal muscles before treatment and 4 weeks and 6 months after insertion of the new dentures. The results suggest, however, that a long edentulous period is visible not only in the functioning of the masticatory muscles, in terms of decreased EMG activity, but also as decreased density of the muscles which implies muscle atrophy, as seen by CT in the masseter and medial pterygoid muscles.

Adult↗

PubMed2004

The effect of an interocclusal appliance on bite force and masseter electromyography in asymptomatic subjects and patients with temporomandibular pain and dysfunction.

The aims of this study were to assess the effect of clenching with or without the presence of an interocclusal appliance (IOA) on bite force (BF) and masseter electromyography (EMG) in patients with temporomandibular pain dysfunction disorders (TMPD) and to compare these results with an asymptomatic age- and gender-matched control group. Ten patients with TMPD (mean age 26.9 years) were compared with eight healthy controls (mean age 25.3 years). Bilateral masseter EMG activity was recorded at rest, while clenching on the BF meter, while clenching on an IOA and while clenching on an IOA together with the BF meter. Significant left to right EMG activity asymmetry was found in the patient group at rest and during multiple clenching tasks in the control group. The patient group had significantly greater EMG activity at rest than controls. For all other tasks, the control group EMG activity was greater than the patient group. Use of an IOA significantly decreased EMG activity in both patient and control groups. BF was significantly greater in the control group on the right side for the different clenching tasks. Insertion of the IOA significantly increased BF in the control group. The results of this study indicate differences in EMG activity and BF during different clenching tasks and between patients with TMPD and asymptomatic subjects.

Adult↗

PubMed2005

The external anal sphincter and the role of surface electromyography.

Assessment of the neuronal control of the external anal sphincter (EAS) has long been restricted to investigating patients with defecation disorders by invasive tools such as needle electromyography (EMG), while less invasive techniques have been regarded as non-suitable for diagnostic purposes. Multichannel surface EMG by means of electrode arrays applied to anal sphincter muscle records and identifies individual motor unit action potentials, their place of origin along the circumference, their repetitive firing frequency, and their progression along the muscle fibres at different levels within the anal canal. These data shed doubts on conventional knowledge about the anatomy of the EAS muscle, and confirms new concepts of anatomical differences between gender. This may eventually be transferred to a new understanding of the role of symmetry and asymmetry of pelvic floor innervation and its role in the pathogenesis of fecal incontinence.

Adult↗

PubMed1997

Feasibility of urodynamic study (combined cystometry and electromyography of the external urethral sphincter) under general anesthesia in children.

BACKGROUND: To assess the feasibility of urodynamic study under general anesthesia (GA) we performed electromyography of the external urethral sphincter (EUS-EMG) on 73 children and cystometry (CM) alone on 10 children. METHODS: Subjects were divided into 3 groups. Those in groups I and II were suspected of having voiding dysfunction with (group I) or without (group II) overt neurospinal defects, while those in group III were thought to be functionally normal. EUS-EMG was performed under light anesthesia following cystourethroscopy to examine structural abnormalities. Atropine sulfate premedication was not used for the anesthetic procedure; muscle relaxants were used only for tracheal intubation. RESULTS: Voiding was observed in 83% of the patients. Among patients who voided, detrusor-external sphincter dyssynergia (DSD) was noted in 7 (38%) group I patients and 6 (19%) group II patients; in group III, voiding was synergic in all patients. In 10 cases, CM alone was carried out both under anesthesia and in the waking state; anesthesia suppressed detrusor hyperreflexia (DH) in all 9 patients but produced no change in bladder compliance. CONCLUSIONS: In children with urinary disorders, urodynamic study under GA following cystourethroscopy is a feasible method for assessing EUS function and documenting DSD; DH is not evaluable, however. Stratifying urinary management on the basis of these examinations resulted in satisfactory clinical outcomes.

Adolescent↗

PubMed2004

Clinical significance of functional constipation categorized by colonic transit time and pelvic floor electromyography.

OBJECTIVE: Functional constipation (FC) is a common gastrointestinal disorder, the incidence of which is increasing each year with the changes in life style and diet, and the age of patients is becoming younger. Correct categorization will guide the treatment of FC and in the present study colonic transit time (CTT) and pelvic floor electromyography (PFE) were evaluated for their clinical significance in categorizing FC. METHODS: Thirty-two cases of FC diagnosed by Rome II criteria with a duration of 6 months to 30 years were enrolled. Radio-opaque markers were used to detect CTT, the transit index (TI) and colonic evacuation rate; PFE was used to observe whether there was any paradoxical movement between the pelvic floor and abdominal muscles. RESULTS: Colonic transit time was recorded in 32 patients: 20 had outlet obstruction constipation and 12 had slow transit type. In the outlet obstruction type, PFE showed varying degrees of paradoxical movement between the muscles, whereas in the slow transit type, only 4 cases showed it. CONCLUSION: Functional constipation can be categorized by CTT and PFE, which are simple, painless and feasible to perform.

Adult↗

PubMed2004

Role of uterine artery velocimetry using color-flow Doppler and electromyography of uterus in prediction of preterm labor.

AIM: To evaluate the role of Doppler waveforms of uterine vessels and electromyography (EMG) of the uterus in predicting preterm labor. METHODS: One hundred ante-natal women at >or=24 weeks of gestation who fulfilled the selection criteria were included in the study. A single Doppler recording for bilateral uterine vessels was taken at >or=26 weeks gestation using the transvaginal route. Transabdominal EMG of the uterus was recorded serially at 4-week intervals from 24 weeks until delivery or until 37 weeks were completed. RESULTS: Women with a sensation of heaviness in the lower abdomen during pregnancy had a significant association with preterm delivery. Of the three Doppler indices, the systolic/diastolic ratio and the resistivity index of uterine vessels were found to have a sensitivity as high as 83-95% for the prediction of preterm labor. The electrical activity of uterine musculature, as recorded using EMG, showed that there was a statistically significant difference between the electrical activity recorded for the two groups at 31 weeks and later, while the duration of burst activity was significantly longer in the preterm group at 26 weeks and later. CONCLUSIONS: Patients with a dull aching sensation in the lower abdomen should not be neglected. Doppler of the uterine vessels and EMG of the uterus could prove to be a good predictor of preterm labor.

Adolescent↗