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At least 469 records · Page 26Linked to original sources
PubMed2003

A preliminary study of modification of gait in real-time using surface electromyography.

Modification of abnormal gait was attempted in real-time using a surface electromyography-based protocol to teach recruitment of the anterior tibialis at the correct time in the gait cycle. Two children diagnosed with cerebral palsy were able to learn volitional control of the anterior tibialis as demonstrated by improved clearance of the toe on the swing phase of the gait and newly learned ability to recruit and relax the anterior tibialis. The children were able to walk with the new gait pattern and reproduce the old one at will. Implications for future research in this area are discussed.

Biofeedback, Psychology↗
PubMed2001

Evaluation of fatigue in Parkinson's disease patients with stimulated single fiber electromyography.

OBJECTIVES: Fatigue is a disabling and dopa-resistant symptom in Parkinson's disease (PD). Pathological studies have shown that both peripheral and central cholinergic systems are involved in PD. Electrophysiological investigation showed decremental muscle responses following repetitive nerve stimulation (RNS). We hypothesized that fatigue in PD patients may be secondary to cholinergic defect at the neuromuscular level. MATERIAL AND METHODS: Twenty PD patients with disabling fatigue symptoms were enrolled. We used stimulated single fiber electromyography (s-SFEMG) to evaluate the neuromuscular junction of these patients. For every patient, at least 15 muscle fibers were tested at the rate of 10 Hz with the method described by Trontelj et al. The individual mean consecutive difference (i-MCD) was obtained from 100 constant consecutive single fiber potentials. The i-MCD values in each patient were averaged to obtain the mean MCD (m-MCD). RESULTS: None of the 20 PD patients with disabling fatigue symptoms had an m-MCD over 29 micros or more than 10% of the i-MCD values over 41 micros. The neuromuscular junction was intact in terms of normal jitter (expressed as MCD) and an absence of blocking. CONCLUSION: Our findings indicate that the cholinergic system at the neuromuscular level is not affected in PD patients with fatigue symptoms.

Aged↗
PubMed2001

Maximal respiratory pressures in myasthenia gravis. Relation to single fiber electromyography.

OBJECTIVES: The respiratory muscle weakness was evaluated in mild forms of myasthenia gravis (MG) and was compared with single fiber electromyography results (SFEMG) in the extensor digitorum communis muscle. MATERIAL AND METHODS: We assessed 61 treated MG patients without clinical respiratory involvement (13 ocular forms, 28 form IIa and 20 form IIb patients) by maximal respiratory pressure (MRP) to ascertain whether they were consistent with SFEMG results. RESULTS: Maximal expiratory pressure (MEP) and maximal inspiratory pressure (MIP) were reduced below the lower limit for healthy subjects in 85% and 77% of ocular patients; in 93% and 89% of form IIa, respectively; and in 95% of form IIb. The highest percentage of MEP and MIP reduction showed a positive correlation with increased jitter (r=0.45, P<0.001; r=0.27; P<0.05 respectively) and impulse blocking (r=0.35, P<0.01; r=0.28, P<0.05 respectively). CONCLUSION: We consider MRP measure useful for assessing respiratory muscle weakness in MG patients with subclinical respiratory involvement.

Adult↗
PubMed2003

Optimum trace count necessary for jitter calculation in single-fiber electromyography.

OBJECTIVE: To clarify the optimum trace count for jitter calculation. MATERIALS AND METHODS: Single-fiber electromyography was performed during voluntary contraction (VC-SFEMG) of extensor digitorum muscle in six healthy and five myasthenic subjects. Twenty single-fiber action potential (SFAP) pairs were recorded from each subject. For each pair, 100 consecutive traces were recorded and stored for off-line analysis. Ten different jitters were calculated in 10 consecutive steps for each SFAP pair by increasing the number of traces included to analysis (from 10 to 100). The jitter calculated in each step was compared with that calculated from 100 traces. RESULTS: Sixty was the optimum number of trace count for both myasthenics and normal controls. Using less than 60 traces for jitter calculation revealed lower values. CONCLUSION: Jitter calculation should be performed from at least 60 traces in VC-SFEMG. Less numbers yield lower jitter and may cause diagnostic error.

Action Potentials↗
PubMed2000

Complete denture wearers: electromyography of mastication and texture perception whilst eating meat.

This study was undertaken to evaluate the sensitivity of denture wearers to different food textures and to follow masticatory pattern adaptation with variation in texture using electromyography (EMG) recordings. Nine patients with complete dentures and 9 dentate control patients without any oro-dental pathology were studied. Six different samples of beef were obtained from the same muscle by altering the state of the muscle fibres and by variation of the cooking temperature. The variations in texture were mechanically controlled. Electromyographic activity was recorded during chewing. The patients' subjective appreciation of texture was reported using a 10-cm non-structured analogue scale. The following parameters were analysed: muscle work, number of masticatory cycles, number of rejected samples, initial tenderness, overall tenderness, juiciness, and duration of chewing for each sample in the mouth. Muscle activity was less for the edentulous group, particularly that of the masseter muscles. The masticatory pattern of complete denture wearers was less adapted to each sample texture than was that of the control group. Both groups perceived differences in texture of the samples. It was concluded that although texture perception is little altered, muscular adaptation to the bolus is reduced in patients with complete dentures.

Adaptation, Physiological↗
PubMed2006

Biomechanical correlates of surface electromyography signals obtained during swallowing by healthy adults.

PURPOSE: The purpose of this study was to describe biomechanical correlates of the surface electromyographic signal obtained during swallowing by healthy adult volunteers. METHOD: Seventeen healthy adults were evaluated with simultaneous videofluoroscopy and surface electromyography (sEMG) while swallowing 5 mL of liquid barium sulfate. Three biomechanical swallowing events were analyzed: hyoid elevation, pharyngeal constriction, and opening-closing of the pharyngoesophageal segment. For each biomechanical event and from the sEMG signal, the authors identified onset, peak, and offset time points. From these points, duration measures were calculated. Means and 95% confidence intervals were calculated for each measure. Subsequently, correlations were evaluated between timing aspects of the sEMG traces and each biomechanical event. RESULTS: Swallow onset in the sEMG signal preceded the onset of all biomechanical events. All biomechanical events demonstrated a strong correspondence to the sEMG signal. The strongest relationship was between hyoid elevation-anterior displacement and the sEMG signal. CONCLUSIONS: These results suggest that the sEMG signal is a useful indicator of major biomechanical events in the swallow. Future studies should address the impact of age and disease processes, as well as bolus characteristics, on the biomechanical correlates of sEMG signals obtained during swallowing.

Adult↗
PubMed1998

Acoustic myography, electromyography and bite force in the masseter muscle.

Acoustic myography (AMG) offers some advantages over electromyography (EMG) in certain circumstances, but the use of AMG on the jaw-closing muscles has not been fully tested. The purpose of this study was to examine the relationship between AMG, EMG and force in the masseter muscles of nine healthy male subjects. The AMG was recorded using a piezoelectric crystal microphone and the EMG was recorded simultaneously with surface electrodes. Force was recorded between the anterior teeth with a strain-gauge transducer. Analysis showed that Pearson's correlation coefficient was 0.913 for force/AMG and 0.973 for force/EMG in all subjects, indicating a linear relationship between force, AMG and EMG at the four different force levels tested (25-75% of maximum). It is apparent that AMG may be used as an accurate monitor of masseter muscle force production, although some care is required in the technique.

Acoustics↗
PubMed2003

Can continuous physical training counteract aging effect on myoelectric fatigue? A surface electromyography study application.

OBJECTIVES: To compare the myoelectric onset of muscle fatigue in physically active trained young skiers with respect to elderly skiers and to test whether continuous training can counteract the selective loss of type II muscle fibers usually observed with aging. DESIGN: An observational, cross-sectional study of the myoelectric onset of muscle fatigue in the left tibialis anterior muscles. SETTING: Surface electromyography recorded with portable devices at a downhill ski rescue lodge in the Italian Alps. PARTICIPANTS: Fifty-four physically trained, active skiers (43 men, 11 women; age range, 24-85y). INTERVENTIONS: Questionnaire on physical activity and 2 sustained isometric voluntary contractions at 20% and 2 at 80% of the maximal voluntary contraction level. MAIN OUTCOME MEASURES: Isometric contractions and mean and median spectral frequencies calculated to monitor the myoelectric manifestations of muscle fatigue. RESULTS: Fatigue indices did not differ significantly between younger and older subjects and, thus, did not show a correlation between myoelectric manifestations of muscle fatigue and age in physically active subjects. CONCLUSION: It appears possible that aging skeletal muscles subjected to continuous exercise develop an adaptive response that counteracts the selective loss of type II muscle fibers usually observed in the muscles of elderly sedentary subjects. Our results suggest that physical activity could be considered in the elderly within a broad rehabilitative framework in which appropriate and even tailored physical training could be planned to counteract the physiologic effects of aging on muscle fiber distribution.

Adult↗
PubMed2001

Outcome of surgery for cervical radiculopathy evaluated by determination of trapezius muscle microcirculation and electromyography.

Surgery for cervical radiculopathy was evaluated in 27 patients after anterior Cloward procedure (19 patients) or posterior decompression (eight patients). In addition, we examined 10 conservatively treated patients. Each patient was studied prospectively with regards to the effects on microcirculation in the local trapezius muscle during a fatiguing series of stepwise increased contractions. The right and left muscles were simultaneously examined pre-operatively and postoperatively after 9 months using laser-Doppler flowmetry and simultaneous surface electromyography (EMG). Preoperatively, a reduced microcirculation was found in the most painful side compared with the opposite side. This is in accordance with earlier reports on patients with chronic neurogenic neck pain, who also show reduced muscle tension on EMG. Postoperatively, the muscle blood flow became increased, but only in patients operated on via a posterior approach. A tendency at increased EMG-amplitude and reduced mean power frequency of the EMG was noted. These EMG signs of muscle fatigue suggest increased ability to exhaust the trapezius muscle postoperatively. The observed postoperative changes were consistently more frequent in the less painful side. We conclude from these objective measurements showing only a tendency at increased microcirculation and muscle tension postoperatively, that the effect on the trapezius muscle is limited.

Adult↗
PubMed1999

Restoring hand function in patients with severe polyneuropathy: the role of electromyography before tendon transfer surgery.

Electromyography (EMG) was evaluated as a supplement to clinical examination and biomechanical considerations to optimize forearm donor muscle selection before tendon transfers to 4 functionless hands in 3 patients with slowly progressive polyneuropathies. Two patients had unusually severe Charcot-Marie-Tooth disease; the third patient had idiopathic mononeuropathy multiplex. Standard EMG parameters were used to devise an intuitive muscle grading system, including most importantly interference patterns and motor control, plus motor unit morphology and stability. Given our objective of restoring survivable function despite ongoing polyneuropathy, we found that EMG reveals prognostically important differences among partially denervated candidate muscles that cannot be detected by experienced clinical examiners. Opposition transfer was performed on one hand of each patient. After 39-, 39-, and 51-month follow-up durations, restored opposition was graded as good in these 3 hands. We conclude that EMG provides meaningful guidance in selecting optimal forearm muscles for tendon transfers to hands in the setting of slowly progressive polyneuropathies.

Charcot-Marie-Tooth Disease↗
PubMed2000

Intraoperative electromyography of the superior gluteal nerve during lateral approach to the hip for arthroplasty: a prospective study of 12 patients.

The purpose of this study was to evaluate the incidence of intraoperative superior gluteal nerve irritation and to identify specific surgical maneuvers that may harm the nerve. Continuous intraoperative electromyography (EMG) monitoring of the superior gluteal nerve-innervated muscles (gluteus medius and tensor fascia lata muscles) was performed in 12 patients undergoing total hip arthroplasty. A modified lateral approach was used, including a partial anterior osteotomy of the greater trochanter with splitting of the gluteus medius and vastus lateralis muscles. All patients had a clinical follow-up examination 1 year postoperatively to evaluate abductor muscle function. Irritation of the nerve occurred first during splitting of the gluteus medius muscle, then with increased gluteus medius retraction for exposure of the acetabulum, and finally during positioning of the leg for preparation of the femur. The detected EMG alterations were important because they were found in a single patient with persistent abductor muscle weakness.

Aged↗
PubMed2001

[Electromyography of the infrahyoid muscles - part 2: pathological findings].

BACKGROUND: The infrahyoid muscles (IHM) can easily be used as a neurovascular myofascial flap for reconstructive surgery in the oral cavity and pharynx and especially for functional tongue reconstruction following tumor ablation. METHODS: In order to detect neurogenic lesions caused by neck pathologies, in particular lymph node metastasis, we studied ten patients (nine patients suffering from tongue carcinoma and one patient after traumatic tongue ablation) by preoperative electromyography of the IHM. These results were compared to ten healthy controls. RESULTS: We found no pathological spontaneous activity with the EMG at rest in any patient. During light voluntary innervation, the motor unit potentials (MUP) were normal in controls and in patients with normal ultrasound, CT scans and histologic examination after neck surgery. When pathologic lymph nodes were found in the neck, the number of polyphasic MUP in the ipsilateral IHM was increased in some cases (n = 6), and normal in others (n = 5). Traumatic or radiogenic lesions clearly resulted in pathological EMG findings (n = 6). Maximal innervation of the IHM was obtained during head bending and jaw opening. We found no difference in the discharge pattern of both groups. CONCLUSIONS: Due to their extent lymph node metastasis can lead to neurogenic lesions of the cervical ansa of the IHM. Neurogenic damages are most clearly present after traumatic lesions of the neck (prior operations, radiotherapy). EMG at maximal voluntary contraction instead revealed no lesions. The clinical impact of these demonstrated neurogenic lesions need to be studied by measuring the muscle strength of the IHM.

Adult↗
PubMed2001

[Electromyography of the infrahyoid muscles - part 3: findings after transposition as a myofascial flap in tongue reconstruction].

BACKGROUND: Due to the preservation of its nerval supply the neurovascular infrahyoid muscle flap in tongue reconstruction enables to prevent atrophy of the musculature. In this study the integrity of the infrahyoid muscles (IHM) after transposition into the oral cavity was examined by means of electromyography. METHODS: 17 patients after partial or complete reconstruction of the tongue with IHM were studied at varied times after surgery. The IHM in the oral cavity was inserted by a concentric needle electrode and activity at rest as well as the discharge pattern at maximal voluntary innervation was evaluated. During light voluntary activity a motor unit potential (MUP) analysis were performed. RESULTS: 13 of 17 patients (76,5 %) in total revealed electromyographic activity in the transfered IHM flaps. Within the first 6 months after surgery 71,5 % of the patients or 77,8 % of the IHM flaps showed activity. After 6 months in 61,5 % of the patients or 64,7 % of the IHM flaps muscular activity was demonstrated. In 84,6 % of the patients or 88,2 % of the flaps we could detect neurogenic lesions at least once. Maximal voluntary contraction showed a discrete activity pattern in 63 %. In 26 % of all cases we found a discrete to reduced interference pattern and in 10 % a reduced interference pattern. CONCLUSIONS: Functioning muscle tissue could be demonstrated in the most IHM flaps, but almost all of the studied muscles showed neurogenic lesions with a loss of motor units due to the traumatic surgery. Maybe bioelectrical stimulation of the Ansa cervicalis with implantable amplifiers will lead to better flap contractility in the future.

Electromyography↗
PubMed2003

Pearls and pitfalls in the use of electromyography and nerve conduction studies.

This review aims to remind you of some of the fallibility of electromyography (EMG) and nerve conduction studies, as well as their usefulness. Areas covered will include designing the nerve conduction and EMG study, variables that effect the test including aging and temperature, how extensive a study needs to be, the importance of patient cooperation, interpretation of spontaneous discharges, types of electrical interference, and the importance of looking at the waveforms themselves from nerve conduction studies.

Age Factors↗
PubMed1987

[Single-fiber electromyography, examination technic and findings].

Single-fibre electromyography has become much easier because of the advantages offered by modern computerised EMG equipment. Fibre density, jitter and the frequency of blockings can thus be examined with relative reliability. The technique allows a sensitive diagnosis of disturbances of neuromuscular stimulus transmission. Furthermore, different pathological results obtained in patients suffering from neuropathies or myopathies (12 controls, 65 patients) proved the diagnostic value of single-fibre EMG. The method is a valuable addition to conventional EMG. The examination technique is described and illustrated by various examples.

Electromyography↗
PubMed1990

Influences of sex and level of performance on freestyle stroke: an electromyography and kinematic study.

Surface Electromyography (EMG) of the upper arm was performed on 50 subjects (30 males and 20 females). The following six muscles were studied: M. flexor carpi ulnaris, M. brachioradialis, M. biceps brachii, M. triceps brachii and two parts of the M. deltoidus (anterior and medialis). A cinematographical analysis was synchronized with the EMG's recorded during swims at maximal speed. The kinematics data were: hip displacement, stroke rate and five stroke phases measured from the arm-trunk angles. EMG measurements were normalized for each subject and analysed using the statistical method of principal component analysis. The best swimmers, at the same relative effort, had a greater hip displacement, lower electrical muscular activity and more selective recruitment, indicating greater efficiency. The role of each muscle during the different phases was in agreement with previous investigations (2, 11, 13, 14, 19). The swimmer's technique, particularly the position of the upper arm during the push phase, influenced these results. Time parameters of the stroke were not significantly different for the various swimmer's levels. The conclusions were similar, for the females, however, with a worse displacement of the hip.

Adolescent↗
PubMed1991

[Complex movement analysis: dynamic study of the effect of a tape bandage on pronation in high-jumping with three-dimensional movement analysis and electromyography].

Overuse syndromes in the lower extremity are a frequent problem in athletics, especially in jumping events. Athletes notice a comfortable support by using ankle taping without restriction of their performance. Up to now no objective data is available about efficiency of taping against overpronation which is frequent in high jumping. In high jumping without boots little difference of pronation between taped and untaped take off leg was found. In contrast in jumping with spikes boots a marked pronation during take off was found, which was reduced by ankle taping with a reduction of maximum medial malleolar medialisation by 77%, reduction of pronation time by 33% and time of maximum pronation by 8.2% in the take off leg. Surface electromyography showed an increased activity of M. peroneus longus by 30.7% as a plantarflector and pronator muscle with ankle taping. Activity of other jump supporting muscles of the lower extremity was little influenced.

Adolescent↗
PubMed1995

Electromyography with acrylic plug surface electrodes after delivery.

Pelvic floor neuromuscular function was evaluated with surface electromyography using acrylic plug electrodes and interactions between neuromuscular function and factors pertinent to the delivery process were explored. Fifty-two women who were primiparas participated in this prospective cohort study. Circumvaginal and circumrectal muscles were assessed. Corrected vaginal-rectal flicks and holds were calculated. The results were compared by delivery route, birthweight, race, lactational status, and delivery anesthetic and to a group of nulliparous subjects. The mean interval from delivery was 46.3 days. Birthweight, race, lactational status, and anesthetic technique were not associated with statistically significant changes in electrical activity, although our ability to detect such differences was low due to the small number of subjects. Women who delivered vaginally had lower vaginal flick voltage than those delivering abdominally. Women who delivered vaginally had lower vaginal flick and hold voltages and rectal flick voltage when compared with nulliparous women studied earlier. Abdominally delivered women had values similar to the nulliparous group. Women delivering vaginally had less surface electromyographic activity in the circumvaginal muscles, implying that vaginal delivery impairs the neuromuscular function of the pelvic floor.

Adolescent↗