Activity of Muscles in Non-Myopathic Conditions
A. Bakiya, K. Kamalanand, R. L. J. De Britto in Mechano-Electric Correlations in the Human Physiological System, 2021
Electromyography is the electrodiagnostic technique for recording and analyzing the electrical potentials generated from the neuromuscular system (Ambikapathy & Krishnamurthy, 2018; Ambikapathy et al., 2018; Bakiya & Kamalanand, 2018; Bakiya et al., 2020). The recorded electrical potentials are utilized for the diagnosis of several neuromuscular disorders such as myopathy, multiple sclerosis, peripheral neuropathy and amyotrophic lateral sclerosis (Sadikoglu et al., 2017; Duque et al., 2014), as discussed in the earlier chapters. In general, the EMG recording instruments are designed to record electrical signals in the frequency range of 20 and 450 Hz. However, the frequency range of healthy EMG signals is between 30 and 60 Hz (Duque et al., 2014; Subasi, 2012).
The neurologic approach
Stanley Berent, James W. Albers in Neurobehavioral Toxicology, 2012
‘Electromyography’ refers to nerve conduction studies and the needle electromyography examination. The EMG examination evaluates the physiological function of the peripheral nervous system. The most important application is to patients with suspected disorders of anterior horn cells, nerve roots, peripheral nerves, neuromuscular transmission, or muscle. The EMG examination is well standardized, with established sensitivity, specificity, and reproducibility. Board certification examinations provide standards of threshold levels of competence. EMG has special application for disorders potentially caused by neurotoxicants, particularly those that produce neuropathy. EMG results are used to classify the neuropathies into broad categories, narrowing the differential diagnosis. Because of their precision, EMG studies are increasingly important to clinical pharmaceutical studies, including their role in identifying potential neurotoxicity. The methodology employed in EMG evaluations is discussed in more detail in Chapter 9 of Volume II.
Answers
Samar Razaq in Difficult Cases in Primary Care, 2021
DMD is the commonest of the muscular dystrophies and is inherited in X-linked recessive fashion. The term ‘muscular dystrophy’ refers to a group of muscle disorders that are degenerative and inevitably progressive. The genetic defect in DMD affects the production of dystrophin, a protein that forms part of the cytoskeleton of muscle cells. DMD occurs almost exclusively in males, as it can occur in females with Turner’s syndrome (XO) where the protective effect of the second X chromosome is missing, allowing expression of the recessive allele on the affected sex chromosome (Ferrier, et al., 1965). The young child is usually slow to walk and has a tendency to fall often. Gower’s sign describes the child getting up in a particular way, climbing up his or her legs because of weakness. However, this is not specific to DMD and can occur in any cause of muscle weakness. Most children will be in a wheelchair by their twelfth birthday because of the devastating progression of the illness. Up to a third of children may have concomitant learning difficulties, which may be accounted for by the presence of dystrophin in neuronal cells also. CPK levels are hugely elevated early in disease. As the disease progresses and normal muscle is replaced by redundant tissue, the CPK levels will gradually drop and may not be too far off normal. Electromyography may be useful but diagnosis is by muscle biopsy. Management revolves around maintaining independence for as long as is possible and meeting the child’s social and psychological needs. Cardiorespiratory complications increase with time, and death usually occurs by the second decade of life.
Blue-blocking filters do not alleviate signs and symptoms of digital eye strain
Published in Clinical and Experimental Optometry, 2023
Jesús Vera, Beatriz Redondo, Alba Ortega-Sanchez, Alejandro Molina-Molina, Rubén Molina, Mark Rosenfield, Raimundo Jiménez
Electromyography is a reliable technique to study muscle function through analysis of the electrical signals originated during voluntary or involuntary muscle contractions.15 Previous studies have proved that electromyography is a useful non-invasive tool for the assessment of muscle activation and fatigue.16,17 More specifically, the activity of the orbicularis oculi (OO) is sensitive to visual discomfort and asthenopia in stressful visual conditions, and it has been proposed as an objective measure of DES.18–23 This parameter has been demonstrated to be sensitive to the manipulation of viewing distance, visual stress, prolonged near work, and display type (e.g., 2D versus 3D displays) as the electromyography activity from the OO increases during visually stressful conditions.18,19,22,24 However, Gowrisankaran and colleagues found that while the OO muscle response varied with refractive error, as well as changes in glare, contrast and font size, it was insensitive to accommodative and convergence stress while reading.19
Toward bio-kinematic for secure use of rehabilitation exoskeleton
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
J. Charafeddine, D. Pradon, S. Alfayad, S. Chevallier, M. Khalil
Gait Laboratory (Raymond Poincaré Hospital, Garches, France). A bio-kinematics study was conducted in a large room; where the patients walked a straight line for 10 meters. The acquisition system includes:Video equipment to record the front and the profile of the patient.An optoelectronic system to measure the segment kinematics and the joint angles of the knee and the hip steps with respect to each foot (left and right).Ground force platforms to record dynamics (recording of ground reaction forces and the moments).An electromyographic system to record muscle activity. Electrodes were placed at the level of two biarticular muscle groups (quadriceps and hamstrings) for the knee and the hip on each leg (left and right). Everything was synchronized and connected to a computer for data acquisition. Kinematic measurements and electromyographic data were taken and recorded for three rhythms velocities (fast, normal and slow) and for 11 walking cycles at each velocity.
Short-term effects of postural control by standing on a tilting board in patients with Parkinson’s disease
Published in Physiotherapy Theory and Practice, 2021
Naoya Hasegawa, Keita Ishikawa, Yuki Sato, Yasuhide Nakayama, Tadayoshi Asaka
Foremost is the small sample size, which may have limited the identification between-group differences. Second, the tilted support group experienced a single long-duration trial, while the voluntary forward lean group experienced multiple, short repeated trials. This difference may play a role in the between-group differences as the interpretation hinges upon sensory re-weighting and adaptation. Third, the BBS was used for assessing clinical balance function in this study. Leddy, Crowner, and Earhart (2011) showed a ceiling effect for people with PD and there are no items to assess reactive postural control in BBS. Therefore, the other clinical tests such as the Fullerton Advanced Balance Scale or Mini Balance Evaluation System Test could be more appropriate. The learning effects of this intervention should be further investigated with a retention test. Furthermore, muscle activities should be investigated using electromyography to understand the mechanism of the effects of this intervention.
Related Knowledge Centers
- Biomechanics
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- Electrodiagnostic Medicine
- Prosthesis
- Neuromuscular Disease
- Skeletal Muscle
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