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Electromyography is an useful method for the postoperative follow-up of carpal tunnel syndrome. In patients without sensory and motor signs EMG is able to differentiate those still suffering from subjective symptoms such as pain and paraesthesias.
Voluntary faecal continence after corrective surgery for anorectal malformations was assessed via electromyography (EMG) of the external sphincter muscle in 20 patients with anorectal malformations. Six normal children served as controls. Function of the external sphincter in patients with high type anomaly was disturbed from the points of tonic activity, inflation reflex, and activity during further rectal filling. Patients with a positive inflation reflex, regardless of the type of anorectal malformation, had good Kelly scores. Phasic activity was observed in patients with high-type anomaly, and in normal subjects and patients with other types of anomaly. Therefore, patients with high-type anomaly may acquire compensatory voluntary anal continence through training.
Since 1975 the endorectal pull-through operation for Hirschsprung's disease has been favoured in this department. Out of 16 patients, 12 were examined 8 months to 6 years later by ano-rectal manometry and external sphincter electromyography. The results indicate a normal postoperative rectal capacity and rectal sensibility. There was no internal sphincter relaxation in response to a rectal distention. Resting and reflex activity of the external and sphincter were normal.
BACKGROUND: Laryngeal electromyography (LEMG) is a valuable diagnostic/prognostic test for patients with suspected laryngeal neuromuscular disorders. OBJECTIVE: To report our experience with diagnostic LEMG at the Center for Voice Disorders of Wake Forest University and to evaluate the impact of LEMG on clinical management. METHODS: Retrospective chart review of 415 patients who underwent diagnostic LEMG over a 5-year period (1995-1999). RESULTS: Of 415 studies, 83% (346 of 415) were abnormal, indicating a neuropathic process. LEMG results altered the diagnostic evaluation (eg, the type of radiographic imaging) in 11% (46 of 415) of the patients. Unexpected LEMG findings (eg, contralateral neuropathy) were found in 26% (107 of 415) of the patients, and LEMG results differentiated vocal fold paralysis from fixation in 12% (49 of 415). Finally, LEMG results altered the clinical management (eg, changed the timing and/or type of surgical procedure) in 40% (166 of 415) of the patients. CONCLUSIONS: LEMG is a valuable diagnostic test that aids the clinician in the diagnosis and management of laryngeal neuromuscular disorders.
OBJECTIVE: The objective of this study was to determine whether mechanical force, manually-assisted (MFMA) spinal manipulative therapy (SMT) affects paraspinal muscle strength as assessed through use of surface electromyography (sEMG). DESIGN: Prospective clinical trial comparing sEMG output in 1 active treatment group and 2 control groups. SETTING: Outpatient chiropractic clinic, Phoenix, AZ. SUBJECTS: Forty subjects with low back pain (LBP) participated in the study. Twenty patients with LBP (9 females and 11 males with a mean age of 35 years and 51 years, respectively) and 20 age- and sex-matched sham-SMT/control LBP subjects (10 females and 10 males with a mean age of 40 years and 52 years, respectively) were assessed. METHODS: Twenty consecutive patients with LBP (SMT treatment group) performed maximum voluntary contraction (MVC) isometric trunk extensions while lying prone on a treatment table. Surface, linear-enveloped sEMG was recorded from the erector spinae musculature at L3 and L5 during a trunk extension procedure. Patients were then assessed through use of the Activator Methods Chiropractic Technique protocol, during which time they were treated through use of MFMA SMT. The MFMA SMT treatment was followed by a dynamic stiffness and algometry assessment, after which a second or post-MVC isometric trunk extension and sEMG assessment were performed. Another 20 consecutive subjects with LBP were assigned to one of two other groups, a sham-SMT group and a control group. The sham-SMT group underwent the same experimental protocol with the exception that the subjects received a sham-MFMA SMT and dynamic stiffness assessment. The control group subjects received no SMT treatment, stiffness assessment, or algometry assessment intervention. Within-group analysis of MVC sEMG output (pre-SMT vs post-SMT sEMG output) and across-group analysis of MVC sEMG output ratio (post-SMT sEMG/pre-SMT sEMG output) during MVC was performed through use of a paired observations t test (POTT) and a robust analysis of variance (RANOVA), respectively. MAIN OUTCOME MEASURES: Surface, linear-enveloped EMG recordings during isometric MVC trunk extension were used as the primary outcome measure. RESULTS: Nineteen of the 20 patients in the SMT treatment group showed a positive increase in sEMG output during MVC (range, -9.7% to 66.8%) after the active MFMA SMT treatment and stiffness assessment. The SMT treatment group showed a significant (POTT, P < 0.001) increase in erector spinae muscle sEMG output (21% increase in comparison with pre-SMT levels) during MVC isometric trunk extension trials. There were no significant changes in pre-SMT vs post-SMT MVC sEMG output for the sham-SMT (5.8% increase) and control (3.9% increase) groups. Moreover, the sEMG output ratio of the SMT treatment group was significantly greater (robust analysis of variance, P = 0.05) than either that of the sham-SMT group or that of the control group. CONCLUSIONS: The results of this preliminary clinical trial demonstrated that MFMA SMT results in a significant increase in sEMG erector spinae isometric MVC muscle output. These findings indicate that altered muscle function may be a potential short-term therapeutic effect of MFMA SMT, and they form a basis for a randomized, controlled clinical trial to further investigate acute and long-term changes in low back function.
Discrete or isolated metastasis to the extraocular muscles without an accompanying intraconal or extraconal mass is rare. Although it is estimated that 5% of orbital metastasis involves extraocular muscles only, to our knowledge there are no reports of discrete extraocular muscle involvement from renal cell carcinoma. With discrete extraocular muscle involvement, accurate localization within the infiltrated region of the muscle is of paramount importance in achieving a safe and positive biopsy. We describe a case with discrete extraocular muscle metastasis from a renal cell carcinoma, where a novel technique of FNAB (fine needle aspiration biopsy) of the medial rectus was undertaken, with EMG (electromyography) control and CT (computerized tomography) scan guidance.
The effects of keyswitch stiffness and key action on typing force, electromyography (EMG), and subjective preference were examined. Each subject's own keyboard (with an audible key click and key activation force of 0.72 N) and three keyboards with no key click that were identical in design but had different key activation forces (0.28 N, 0.56 N, and 0.83 N) were used. Subjects (24 female transcriptionists) typed on each keyboard for 15 min while typing force and left hand surface EMG of the finger flexor and extensor muscles were monitored. Subjects then used one of the keyboards at their workstations for 7 workdays and were monitored again. This procedure was repeated for all four keyboards. Typing force and finger flexor and extensor EMG activity were highest for the 0.83 N keyboard. Lowest EMG values were for the 0.28 N and the 0.72 N audible key click keyboards. Baseline (10th percentile) and median (50th percentile) extensor EMG values were significantly higher than flexor EMG values. Peak (90th percentile) EMG values were comparable for flexors and extensors. Mean subjective discomfort was significantly higher for the 0.83 N keyboard at the fingers (36% higher), lower arm (40% higher), and overall (39% higher). Seventeen of 24 subjects preferred the 0.72 N keyboard, 4 the 0.28 N keyboard, and 3 preferred the 0.56 N keyboard. Results suggest that increasing make force causes typing force and EMG to increase but that the ratio of 90th centile typing force to make force decreases as make force increases. Subjective discomfort was significantly higher for the keyboard with 0.83 N make force. Buckling spring keyboards have better feedback characteristics, which may be responsible for a decrease in the amount of typing force and EMG produced.
The detection of the electrical signal from human and animal muscle dates from long before L. Galvani who took credit for it. J. Swammerdam had already shown the Duke of Tuscany in 1658 the mechanics of muscular contraction. Even if 'electrology or localised electrisation' - the original terminology for electromyography (EMG) - contained the oldest biological scientific detection and measuring techniques, EMG remained a 'supporting' measurement with limited discriminating use, except in conjunction with other methods. All this changed when EMG became a diagnostic tool for studies of muscle weakness, fatigue, pareses, paralysis. and nerve conduction velocities, lesions of the motor unit or for neurogenic and myogenic problems. In addition to the measurement qualities, the electrical signal could be induced as functional electrical stimulation (FES), which developed as a specific rehabilitation tool. Almost in parallel and within the expanding area of EMG, a speciality developed wherein the aim was to use EMG for the study of muscular function and coordination of muscles in different movements and postures. Kinesiological EMG and therewith surface EMG can be applied in studies of normal muscle function during selected movements and postures; muscle activity in complex sports; occupational and rehabilitation movements; isometric contraction with increasing tension up to the maximal voluntary contraction, evaluation of functional anatomical muscle activity (validation of classical anatomical functions); coordination and synchronization studies (kinematic chain); specificity and efficiency of training methods; fatigue; the relationship between EMG and force; the human-machine interaction; the influence of material on muscle activity, occupational loading in relation to lower back pain and joint kinematics. Within these various applications the recording system (e.g. the signal detection, the volume conduction, signal amplification, impedance and frequency responses, the signal characteristics) and the data-processing system (e.g. rectification, linear envelope and normalization methods) go hand in hand with a critical appraisal of choices, limits and possibilities.
Estimates of spinal forces are quite sensitive to model assumptions, especially regarding antagonistic co-contraction. Optimization based models predict co-contraction to be absent, while electromyography (EMG) based models take co-contraction into account, but usually assume equal activation of deep and superficial parts of a muscle. The aim of the present study was to compare EMG based and optimization based estimates of spinal forces in a wide range of work tasks. Data obtained from ten subjects performing a total of 28 tasks were analysed with an EMG driven model and three optimization models, which were specifically designed to test the effects of the above assumptions. Estimates of peak spinal forces obtained using the different modelling approaches were similar for total muscle force and its compression component (on average EMG based predictions were 5% higher) and were closely related (R > 0.92), while differences in predictions of the peak shear component of muscle force were more substantial (with up to 39% lower estimates in optimization based models, R > 0.79). The results show that neither neglecting antagonistic co-contraction, nor assuming equal activation of deep and superficial muscles, has a major effect on estimates of spinal forces. The disparity between shear force predictions was due to an overestimation of activity of the lateral part of the internal oblique muscle by the optimization models, which is explained by the cost function preferentially recruiting larger muscles. This suggests that a penalty for active muscle mass should be included in the cost function used for predicting trunk muscle recruitment.
In this study, two methods were presented in order to evaluate objectively the comfort of head rests in cars using surface electromyography (SEMG). First, the Amplitude Probability Density Function (APDF) was computed. Extremely low level intensity activities were measured. No significant differences were observed on SEMG global activity between experiments with and without a head rest. Second, instead of computing one APDF, several APDF were calculated over time. Analyses focused on the rate of evolution of APDF parameters. This was a time varying APDF (TAPDF). This last method allowed a better diagnosis than the first one. For drivers, significant decreases in SEMG activity were observed when using a head rest. For passengers, a contradictory increase in SEMG activity was observed during experiments with a head rest. This observation was explained by the seat back angle chosen by passengers.
This study examines muscle tension and subjective muscle tension awareness while using a computer mouse positioned to the right of a standard computer keyboard and a centrally positioned trackball. Seventeen volunteer subjects experienced in mouse and trackball use were seated at an ergonomically adjusted workstation. Surface electromyography (sEMG) and subjective muscle tension levels were recorded from four muscle groups (left sternocleidomastoid/scalene, right upper trapezius, right posterior deltoid, and right lower trapezius/rhomboids) during 1-min trials with subjects resting with hands in their lap, while using a trackball below the centre of the keyboard, and while using a mouse immediately to the right of a 101-key keyboard. All subjects showed significantly higher mean sEMG activity recorded from the right upper trapezius, right posterior deltoid, and right lower trapezius/rhomboids during mouse use to the right of a standard keyboard (arm abducted) compared to using a trackball positioned centrally, (p < 0.001). sEMG levels remained elevated during the entire trial period of right side mouse use without evidence of microbreaks (< 1 s epochs of low sEMG activity). sEMG activity from the left sternocleidomastoid/scalene muscles showed no significant change from baseline in any condition. Subjective reports of muscle tension did not correlate with sEMG activity. The authors predict that there will be an overall increase in reports of upper extremity musculoskeletal disorders (UEMSD) and computer related disorders (CRD) when people abduct their arms in order to reach a mouse positioned to the side of standard width, or wider keyboards. Discussed are the applications of sEMG for evaluation of computer keyboard and pointing device use, appropriate ergonomic equipment design, and a methodology for improving muscle awareness, strengthening, relaxation, and workstyle practices to promote healthier computing.
OBJECTIVES: Urethral dysfunction may lead to a deterioration of kidney function and be life-threatening. A thorough diagnosis of the pathophysiology is consequently vital to ensure the correct treatment is given. MATERIAL AND METHODS: In this study, 34 adult patients suspected of a urethral etiology giving rise to urinary retention, urgency or chronic lower urinary tract infections were investigated by uroflowmetry with simultaneous electromyography and voiding video cystourethrography. CONCLUSIONS: Both methods proved to be essential for an accurate assessment of the pathological state.
In veterinary practice electromyography is a useful diagnostic technique for differentiating neuropathies, junctionopathies, and myopathies. The electromyogram gives information on the state of activity of motor neurons at rest, in reflex contraction, and in voluntary contraction. As a research tool, the electromyogram can be used to understand the complexity of the neuromuscular system. It has applications in horses for assessing muscle activation patterns and for providing a more complete understanding of the pathology of the muscles and nerves.
The aim of this study was to investigate to what extent women with superficial dyspareunia can be diagnosed for both partial vaginismus (PaV) and vulvar vestibulitis (VVS) and to discover to what extent surface electromyography (sEMG) of the pelvic floor muscles (PFM) can distinguish between women with PaV solely, PaV+ VVS, and asymptomatic women. A total of 224 consecutive women with superficial dyspareunia were examined clinically for both PaV and VVS diagnoses. We examined 47 women with PaV+/-VVS and 27 asymptomatic women with sEMG of the PFM. The results showed that 102/224 women with superficial dyspareunia and 33/47 women with PaV in the sEMG part of the study had both PaV and VVS. All women with VVS had vaginismus, while 42/224 had PaV but not VVS. sEMG measurements revealed no significant differences between the three groups of women (PaV solely, PaV + VVS, and asymptomatic). Almost half of the women with superficial dyspareunia referred to our clinic have both the diagnosis PaV and VVS. sEMG was not a method of any value to distinguish between women with PaV solely, PaV + VVS, or asymptomatic women. The increased tone found clinically in the PFM of women with PaV+/-VVS may be of other origin than electrogenic contractions.
The aim of this study was to characterize forearm muscle fatigue identified by the decrease in electromyogram median frequency and/or fingertip force during intermittent exercise. Nine elite climbers (international competitive level, USA 5.14a on sight) and ten non-climbers were instructed to maintain a fingertip force of 80% of their maximal voluntary contraction force on a dynamometer mimicking a rock climbing grip during a 5 s effort/5 s rest cycle for 36 repetitions (i.e. 6 min of exercise). Elite climbers lasted twice as long as non-climbers (climbers: 3 min; non-climbers: 1 min 30 s) before the force could no longer be maintained (i.e. the failure point). After this moment, fingertip force decreased and stabilized until the end of the exercise around 50% maximum voluntary contraction force in non-climbers and 63% in elite climbers. Electromyogram median frequency showed a greater decrease in non-climbers than in elite climbers before the failure point. No change in median frequency was observed after the failure point in elite climbers or in non-climbers. These results confirm that elite climbers are better adapted than non-climbers for performing the intermittent fingertip effort before the failure point. After this point, the better fingertip force of elite climbers suggests different forearm muscle properties, while the electromyography results do not provide any indication about the fatigue process.
This study was aimed at evaluating the effects of a novel physiotherapy machine called MAGMA (AntiGravitary Modification of the Myotensions of Asset) on postural and masticatory muscles of subjects with myogenic cranio-cervical-mandibular dysfunction (CMD), by using surface electromyography (sEMG). Fifteen subjects, nine males and six females (mean age 27.6 years), with CMD were included in the study. The bilaterally monitored muscles were: masseter, anterior and posterior temporalis, digastric, posterior cervical, sternocleidomastoid, and upper and lower trapezius. All muscles were monitored at rest, with a second record of maximal voluntary clenching (MVC) for both the masseter and anterior temporalis. Patients were subjected to MAGMA therapy for one session/week of 30 min over ten weeks. The surface EMG activity was recorded twice, at the baseline and at the end of the therapy. After MAGMA therapy, the sEMG activity at rest of the monitored muscles was significantly better when compared to the baseline; the only exception was the anterior and posterior temporalis muscles which did not improve. On the contrary, with the MVC, all the monitored muscles (masseter and anterior temporalis) significantly improved their sEMG activity. Although more investigations are needed, these results indicate that the use of such antigravitary therapy can provide a tool for resolving myogenic CMD.
The purpose of this study was to determine if the advantages and disadvantages of a new automotive seating concept, known as the micro-adjuster control system, could be reliably evaluated using both a physiological assessment technique (i.e., electromyography [EMG]) and a subjective questionnaire. The results indicate that psychophysical measures of discomfort and the root mean squared (RMS) activity of the EMG are statistically related, r (8) = -.788, p =.020. More specifically, subjective perceptions of comfort were found to improve with decreasing levels of muscle activity. This implies that seat comfort can be evaluated on the basis of physiological as well as subjective responses to prolonged driving. This finding should drastically improve automobile seat design efforts.
Electromyography (EMG) plays a key role in the diagnostic evaluation of ALS. This paper deals with the contribution of conventional needle EMG and electroneurography to the neurophysiological assessment of ALS. In addition, special EMG techniques such as single fibre EMG and macro EMG are discussed as they mirror the decline of the number of motor units during the disease process and the remodelling capacity of the surviving motor units.