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At least 1,351 records · Page 75Linked to original sources
PubMed1992

Somatosensory evoked potentials (cutaneous nerve stimulation) and electromyography in lumbosacral radiculopathy.

In order to evaluate the usefulness of SEP with cutaneous nerve stimulation in lumbosacral radiculopathy, we investigated 19 patients by EMG including H-reflex and SEP. All patients had radiculopathy proven by myelography and/or CT scan and, if indicated, operative treatment. The findings by EMG and SEP were compared with operative and radiological findings. In this preliminary study, SEP was as sensitive as EMG in detecting lumbosacral radiculopathy. Further investigation seems justified.

Adult↗
PubMed1987

Relationships between electromyography and kinematics in human stepping strategies.

Kinematic and electromyographic (EMG) parameters were analyzed on phase plane diagrams of human stepping motions performed over an obstacle of varying height. A videomotion analysis system was used to record the displacement of 5 reflective markers placed on the subject's lower limb joints. Surface bipolar electrodes were placed on the rectus and biceps femoris muscles. Results revealed systematic differences in the EMG patterns of the rectus femoris between initial and subsequent trials in the 3 conditions of obstacle height. In the initial trials there was an episode of EMG activity right before or during the transition from knee flexion to extension. In the subsequent trials this episode was shifted toward maximum knee extension velocity, leaving a period of silence between the initial burst and this episode. On the other hand, the biceps femoris was rarely silent and particularly active during the flexion phase, reflecting its possible role in active knee flexion and postural control during the dynamic phase of stepping. The increase in phase plane size with obstacle height appears related to the amplitude of the initial EMG burst of the rectus femoris. Phase plane diagrams combined with EMG appear to be an appropriate approach to explore the dynamics of human movement strategies. The results suggest that control mechanisms for the flexion and extension phases are different and may be involved in fine tuning the stepping strategy for subsequent trials.

Electromyography↗
PubMed1982

Electromyography of pericranial muscles during treatment of spontaneous common migraine attacks.

In 7 patients given a standard treatment during spontaneous attacks of common migraine, activity in the temporal and sternocleidomastoid muscles was studied for 140 min. Pain and nausea ratings were taken with 20 min intervals. Baseline recordings were obtained from all patients during a period without headache and from 8 dental students without a history of migraine. During the attack of migraine, activity in the anterior temporal muscles significantly exceeded the patient's own baseline recordings and all muscles were activated more strongly than in the control sample. The increase in per cent of maximal muscle activity was insufficient to account for ischemic pain. Following treatment the activity of the temporal and sternocleidomastoid muscles decreased in 5 patients at the same time as the pain and nausea to the level of the controls. It is suggested that the moderate increase of activity on admission was a residual from stronger contractions earlier in the attack. In addition to cessation of the attack, placement in supine position and intake of diazepam may have contributed to the decline of muscle activity.

Adolescent↗
PubMed1992

The use of electromyography and muscle palpation in the diagnosis of tension-type headache with and without pericranial muscle involvement.

The Headache Classification Committee of the International Headache Society recently issued revised diagnostic criteria for headache disorders. According to these criteria, tension-type headache may be subclassified depending upon whether pericranial muscle disorder is found. The presence or absence of pericranial muscle disorder was to be determined by palpating the muscles for tenderness or by measuring electromyographic (EMG) activity. In this study, pericranial muscles were palpated, and EMG activity was measured in 27 episodic tension-type headache patients and 32 headache-free controls. All testing was done while the subjects were in a headache-free state. Muscle tenderness was positively associated with the diagnosis of tension-type headache. Headache subjects exhibited significantly higher levels of temporal EMG activity compared to controls, but EMG data were of little use in assigning individual subjects to diagnostic groups. Measures of muscle tenderness and hyperactivity were only weakly associated. Pericranial muscle tenderness and elevated EMG activity may index different aspects of abnormal muscle function.

Adult↗
PubMed1994

Chronic pain after soft-tissue injury of the cervical spine: trapezius muscle blood flow and electromyography at static loads and fatigue.

Microcirculation in the upper portion of the right and left trapezius muscles was measured percutaneously by laser-doppler flowmetry (LDF) during two 10-min-long series of alternating 1-min periods of static contraction and rest determined electromyographically (EMG). Twenty-five patients with pain persisting after a soft-tissue injury of the neck were studied. Pain assessments by using visual analogue scales and drawings showed 13 patients with predominantly unilateral and 12 with bilateral neck-shoulder pain, in some cases with arm pain and numbness. Mean age was 41 (23-58) and 39 (22-54) years and a female/male ratio 8:5 and 10:2, respectively. Stepwise increased contraction was induced by keeping straight arms at 30 degrees, 60 degrees, 90 degrees and 135 degrees of elevation, and repeated with a 1 kg (women) or 2 kg (men) hand loads. Signal processing was done on-line by using a 386SX computer. LDF and EMG values were normalized. Spectral shift of EMG mean power frequency (MPF) for fatigue was analyzed. Muscle blood flow on the "normal" side in the unilateral pain group showed an ordinary increase at increased angle of arm elevation, shoulder torque and EMG amplitude. On the painful side, during increased muscle tension and fatigue, the ability to increase blood flow appeared to be impaired, and there was no consistent increase in either side of the bilateral pain group. EMG amplitude showed a significant positive correlation to the angle of arm elevation and shoulder torque. The rms-EMG (root mean squared EMG) increase was lower in the painful side at high force contraction (non-normalized data).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Electromyography of masticatory muscles in three jaw registration positions.

The purpose of this study was to investigate whether anteroposterior changes in mandibular position affect masticatory muscle activity. The electromyographic (EMG) activity of masticatory muscles during full and partial (10%) clenching in three mandibular bite registration positions--retruded contact position (RCP), intercuspal position (IP), and muscular position (MP)--was studied. Three groups of subjects with different ranges of anteroposterior positioning of the condyles were evaluated (normal occlusion, Class II, Division 2 malocclusion, and dual bite malocclusion). A posterior stabilizing splint for each registration position was made. EMG data were obtained from three bilateral muscles (masseter, anterior temporal, and posterior temporal). Clenching in the RCP elicited the lowest masseter muscle activity during full clenching, and the highest anterior temporal and posterior temporal muscle activity during partial clenching. If the relationships of the masticatory muscles are analyzed through a ratio that represents the interaction between biting and positioning muscles (masseter/posterior temporal muscle ratio), the RCP as compared with other positions had the lowest ratio. The RCP required more positioning muscle activity and permitted less biting muscle activity. There was no significant difference in the muscle activity between the IP and MP registrations. Small changes in jaw position (anterior to RCP) are not critical for the masticatory apparatus provided there is good intercuspation. The results of this investigation suggest that intercuspation in RCP is not the optimal position.

Adolescent↗
PubMed1995

Sensitivity and specificity of needle electromyography: a prospective study comparing automated interference pattern analysis with single motor unit potential analysis.

In this prospective study, automated interference pattern analysis (IPA, "Willison analysis", modified by Stålberg et al. 1983) was compared to the quantitative evaluation of mean motor unit potential duration (QMUP) in 239 muscles from consecutive, unselected patients. The sensitivity and specificity of both methods were calculated with respect to the clinically derived final neurological diagnosis, with histology available for 120 examinations. Whereas specificities were not different for the methods, the sensitivity for detection of abnormal vs. normal was 49% for QMUP and 74% for IPA (P < 0.001). The sensitivity for detection of myopathy or neuropathy was 46% or 38% for QMUP and 75% (P < 0.001) or 53% (P < 0.05) for IPA. Thus, in all instances, IPA had superior sensitivity with unchanged specificity as compared to QMUP. The results of a rapid and purely qualitative visual MUP assessment were statistically not different from QMUP. Although widely used, neither of these methods has been evaluated for its reliability in unselected patients with various grades of disease. Our results indicate that in a routine setting, the best diagnostic strategy might be the automated IPA, which can be quickly obtained in several muscles, followed by muscle biopsy in unclear cases.

Adolescent↗
PubMed2005

Electromyography as a measure of peak and cumulative workload in intermediate care and its relationship to musculoskeletal injury: an exploratory ergonomic study.

Injury rates in Intermediate Care (IC) facilities are high and the factors related to these injuries are unclear. The objectives of this exploratory sub-study, which is part of a large multi-faceted study in 8 IC facilities are to: (1) evaluate EMG measured over a full-shift in the back and shoulders of 32 care aides (CAs) as an indicator of peak and cumulative workload (n = 4 x 8 facilities); investigate the relationship between EMG measures and injury indicators; and explore the relationship between EMG measures and other workload measurements. Lumbar EMG was converted to predicted cumulative spinal compression and ranged in CAs from 11.7 to 22.8 MNs with a mean of 16.4 MNs. Average compression was significantly different during different periods of the day (p < 0.001) with highest compression during pre-breakfast when CAs assist most with activities of daily living. Significant differences were found in average compression between low and high injury facilities for 3 of 5 periods of the day (p < 0.010). Peak compressions exceeding 3400 N occurred for very little of the workday (e.g. 11.25s during the 75 min period pre-breakfast). Peak neck/shoulder muscle activity is low (99% APDF ranged from 8.33% to 28% MVC). Peak and cumulative spinal compression were significantly correlated with lost-time and musculoskeletal injury rates as well as with total tasks observed in the CAs (p < 0.01). Perceived exertion was only correlated with peak compressions (p < 0.01). Facilities with low injury rates provided significantly more CAs (p < 0.01) to meet resident needs, and subsequently CAs performed fewer tasks, resulting in less peak and cumulative spinal loading over the day.

Back↗
PubMed2005

Surface electromyography of the paravertebral muscles in patients with chronic low back pain.

OBJECTIVE: To investigate the differences in the electromyographic signals of patients with chronic low back pain (CLBP) and healthy subjects. DESIGN: Cross-sectional study with a matched-pair design. SETTING: University hospital. PARTICIPANTS: Thirty-one patients with CLBP and 31 healthy, matched-pair controls. INTERVENTIONS: The mean rectified surface electromyographic amplitude and muscle strength were measured during maximal voluntary contraction (MVC). During an endurance test at 60% of MVC, the electromyographic parameters of the 2 groups were compared.Main outcome measure Electromyographic measuring of local fatigue, which can be described with changes in the median frequency or by a different parameter of the power spectrum called frequency banding. RESULTS: The strength measurement revealed a deficiency of 40% in the patients and a deficit in the electromyographic amplitude of approximately 60%, compared with the control group. By pairwise comparison, the decrease in the median frequency during the endurance test was greater in the control group. In the frequency banding of the power spectrum, local fatigue was less pronounced in the CLBP patients in pairwise comparison. CONCLUSIONS: The back muscles of CLBP patients appear to be less fatigable than those of controls. The results can be explained by morphologic changes, but influences such as pain, avoidance of pain, and deconditioning, need to be considered when the results are assessed.

Action Potentials↗
PubMed2004

Cane-assisted gait biomechanics and electromyography after total hip arthroplasty.

OBJECTIVE: To quantify the effects of cane use during walking on hip joint kinematics, kinetics, and muscle activity patterns after unilateral total hip arthroplasty (THA). DESIGN: Nonrandomized experimental design. SETTING: Urban inpatient hospital. PARTICIPANTS: Adults (n=9 men, 2 women) with no history of orthopedic or neuromuscular disease who underwent elective unilateral THA. INTERVENTION: Gait was assessed preoperatively and 4 and 8 months postoperatively. MAIN OUTCOME MEASURES: Three-dimensional hip joint motion and moments and electromyographic patterns of gluteus medius, tensor fascia latae, lateral hamstring, and vastus lateralis were measured during level walking, with and without use of a straight cane. RESULTS: When a cane was held in the contralateral hand, the abduction moment of the affected hip decreased by 26%, whereas that of the contralateral hip increased by 28%. Use of a cane in THA rehabilitation is important because it reduces the load on the operative hip so that bone and soft tissues can heal. Our results suggest that load reduction was successful on the operative side, but the loads on the contralateral side were increased. CONCLUSIONS: After unilateral arthroplasty, subjects using a cane had increased hip abduction moments on the nonoperative hip and decreased hip abduction moments on the operative hip. Clinicians should be mindful of the effects of cane use on the contralateral hip.

Arthroplasty, Replacement, Hip↗
PubMed2004

Evaluation of the complexity of motor unit potentials in anal sphincter electromyography.

OBJECTIVE: Motor unit potential (MUP) morphology can be quantified using parameters describing electrophysiological size and shape (complexity). Traditionally, MUP complexity has been estimated using parameters number of phases and turns. Recently, 'irregularity coefficient' (IR), measuring the length of the MUP curve normalized with its amplitude, has been introduced. The aim of this study was to evaluate IR in the external anal sphincter muscle. METHODS: Sensitivity was examined in 61 patients with chronic cauda equina lesions, and specificity in 75 controls using a standard concentric EMG needle and EMG system with multi-MUP analysis. RESULTS: When evaluated separately the sensitivity of IR was 16% lower, and specificity 5% higher compared to number of turns, with both differences decreasing to only 2 and 1%, respectively, when each of these parameters was added to MUP area and duration. CONCLUSIONS: Our present results suggest that IR provides a similar diagnostic usefulness, but a more appropriate description of MUP complexity compared to traditional MUP parameters. SIGNIFICANCE: IR seems to be suitable to complement one of MUP parameters measuring electrophysiological MUP size in the future quantitative EMG.

Action Potentials↗
PubMed2005

Clinical evaluation of mastication: validation of video versus electromyography.

BACKGROUNDS AND AIMS: The ability to evaluate masticatory function in people with neurological disabilities is important as this function is often compromised in these groups. However, current standard techniques are often impossible in such groups due to cognitive difficulties. This study is a validation of several variables read from standardised video recordings of mastication as indicators of masticatory function. METHODS: Fifteen healthy, fully dentate male subjects were recorded using EMG and by video simultaneously. An evaluation was undertaken of the video parameters (i) to compare their validity against the electromyographic parameters, (ii) to test intra-rater and inter-rater reliability and (iii) to test the ability to discriminate between four model foods differing in hardness. RESULTS: Masticatory time and the number of masticatory cycles counted on video were found to be valid and reliable indicators. In addition, the number of active chewing cycles performed with an open mouth and identification of the chewing side, were found to have reasonable validity and reliability. The former may allow discrimination between food types. CONCLUSION: As an alternative to the complex evaluation of masticatory function, observation of certain parameters from video recording could be an alternative for use in uncooperative patients.

Adult↗
PubMed2005

The contribution of electromyography to the diagnostics of some rare palatal anomalies.

The paper presents the electromyographic (EMG) findings of the soft palate in three patients: a patient with Mohr syndrome and cleft palate, a patient with palatal asymmetry and rhinolalia and a patient with vertical oro-ocular facial cleft with marked asymmetry of the cleft palate. In the first patient, electrical silence was registered in one half of the palate. In the second patient, moderate loss of active motor units was registered in the hypoplastic part of the palate. In the third patient, in spite of asymmetry, the EMG finding was normal on both sides of the palate.

Child, Preschool↗
PubMed2004

Maximal bite forces in healthy young adults as predicted by surface electromyography.

OBJECTIVES: To assess the repeatability of maximal bite force estimates as obtained by submaximal electromyographic-force relationships performed simultaneously and symmetrically in both sides of the mouth. The protocol could be used in a clinical context to obtain indicative values for the occlusal loads to be resisted by the prosthetic reconstructions. METHODS: Ten young healthy subjects performed; (1) a maximum voluntary clench (MVC) directly on their occlusal surfaces; (2) four simultaneous recording of submaximal bite forces (98, 196, 304 and 392 N on two transducers positioned on the left and right first mandibular molars) and surface EMG potentials of the masseter and temporalis anterior muscles. The actual force peak value was recorded. For each subject, a linear regression was run between the simultaneous bite force and EMG submaximal values recorded in the four tests. Using the EMG potentials obtained during the MVC tests, the best fitting line was used to estimate a maximum bite force. Two independent recordings were made by each subject (2 week interval) and analyzed by correlation analysis, paired Student's t-test, and Dahlberg statistic. RESULTS: Significant linear relationships were found between bite force and EMG potentials (p<0.01). The two series of indirect estimates of maximal bite force were correlated (r=0.626) without systematic differences (Student's t, p>0.01). Dahlberg statistic was 115.37 N (approximately 36% of the total variance of the group). CONCLUSIONS: Simultaneously recorded submaximal bite forces and surface EMG potentials of mandibular elevator muscles had a linear relationship. The estimates of maximum bite force were repeatable on a short-term basis (2 weeks). The method limited the disadvantages of bite force recordings, and it could be used to obtain indicative values for the occlusal loads to be resisted by the prosthetic reconstructions.

Adult↗
PubMed2004

Electromechanical delay estimated by using electromyography during cycling at different pedaling frequencies.

The purpose of this study was to propose a new method that can be used to calculate electromechanical delay (EMD) without the measurement of forces. A secondary purpose, as an example of the importance of measuring EMD, was to predict muscle force development events based on the EMG activity of selected muscles during cycling at different pedaling frequencies. EMD was estimated using newly derived equations based on activation dynamics hypothesis. Tibialis anterior (TA) and soleus (SL) muscles of 16 male participants were studied while subjects pedaled at targeted cadences of 60, 80, and 100 revolutions per minute. The estimated EMDs of TA and SL were significantly different from each other with means of 68.1 and 88.7 ms, respectively. The average crank angle for the initiation and time to peak TA contraction was estimated at 75 +/- 35 degrees and 26 +/- 15 degrees before the crank reached top-dead-center (TDC), while the contraction ended at 31 +/- 19 degrees after the TDC on average. The projected starting, peak and end angles of SL contraction activity were 45 +/- 18 degrees , 123 +/- 13 degrees, and 218 +/- 35 degrees after the TDC, respectively. There was no difference among different pedaling cadences observed for these mechanical events. The proposed method was proven to be effective in studying EMD and estimate muscle contraction patterns during cycling.

Adult↗