China
Africa
Explore chapters and articles related to this topic
An Approach to Oculomotor Anomalies in a Child
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Myasthenia gravis less frequently affects children than adults but should be considered in any child with acquired strabismus or external ophthalmoplegia. It is characterized by fatigability and fluctuating muscular weakness. In most cases of pediatric myasthenia gravis, ptosis is present, and strabismus may take any form. In juvenile myasthenia gravis, findings on the examination may include variable and fatigable ptosis, variable strabismus, diminished extraocular movements, a Cogan lid twitch, and improvement with rest or ice. In isolated ocular myasthenia gravis, ancillary testing with acetyl choline receptor antibodies is positive in only 50% of patients.36 Therefore, the diagnosis in children is often based on clinical symptoms and improvement with rest or ice. Tensilon testing and single-fiber electromyography is very difficult in young children and is therefore not often used. In a patient in whom ocular myasthenia gravis is considered, a thorough review or systems and neurological evaluation should be performed to rule out systemic generalization. Treatment in conjunction with a neuromuscular specialist should be considered given the systemic risks of the disease.
Complications of hemodialysis access
Published in Sachinder Singh Hans, Mark F. Conrad, Vascular and Endovascular Complications, 2021
Mia Miller, Prakash Jayanthi, William Oppat
Diagnosis of IMN involves good clinical suspicion with a thorough physical exam. Clinically, sensory findings are more prominent, and these patients often present with a continuous deep, burning discomfort in the distal extremity. There can also be sensory impairment distally, with numbness, paresthesias, and pain in the radicular distribution of all three forearm nerves. Motor compromise includes weakness of muscles innervated by the forearm nerves; with a result of claw-hand deformity, significant loss of function, and severe neurogenic pain.35 Electromyography (EMG) can confirm the diagnosis, especially in the presence of other confounding etiologies. EMG typically shows axonal loss, and low-amplitude or absent responses to sensory and motor nerve stimulation with relatively preserved conduction velocities.57 Treatment includes surgical intervention urgently upon diagnosis, with immediate arterial reconstruction or ligation as previously mentioned. Additional nonsurgical measures include medications for neuropathic pain with aggressive physical therapy to aid in recovery.
Quantitative E.M.G. of E.O.M in patients with congenital fibrosis of the extraocular muscles (CFEOM1)
Published in Jan-Tjeerd de Faber, 28th European Strabismological Association Meeting, 2020
C. Schiavi, C. Bellusci, E.C. Campos
Electromyography with quantitative analysis was performed on EOM of the two adult patients and in the unaffected member. Superior rectus muscle as well medial and lateral rectus muscles were studied. Quantitative electromyography (QEMG) is a general term referring to the technique and conditions used to study the microphysiology of the motor unit (5). It permits the recording of a single muscle fiber action potential. Signal is recorded by using a single concentric needle electrode and the motor unit potential (MUP) is the compound action potential that reflects the electrical activity of the muscle fibers belonging to a single motor unit. During slight voluntary muscle contraction, this compound action potential is characterized by its consistent appearance with regard to shape and amplitude. The relevant parameters may be one or more of the following: amplitude, duration, area, phases and turns. Typically at least 20 MUPs are recorded from each muscle tested (5).
Neuromuscular disorders in women and men with spinal cord injury are associated with changes in muscle and tendon architecture
Published in The Journal of Spinal Cord Medicine, 2023
Larissa Santana, Emerson Fachin-Martins, David Lobato Borges, Jonathan Galvão Tenório Cavalcante, Nicolas Babault, Frederico Ribeiro Neto, João Luiz Quagliotti Durigan, Rita de Cássia Marqueti
Invasive electromyography has identified neuromuscular electrophysiological disorders (NED) in individuals with complete and incomplete SCI.16–19 The most significant effect on nerve waveform amplitude suggests a predominant axonal involvement. However, there are no definitive findings on neuromuscular function changes observed in individuals with chronic SCI.17,18 Among the modalities used to evaluate peripheral nerve lesions, the Stimulus Electrodiagnosis Test (SET) is a non-invasive examination that quantifies nerve and muscle evoked responses using specific parameters of neuromuscular electrical stimulation (NMES) to measure the rheobase, chronaxie, accommodation, and accommodation index.20–22 Invasive electromyography has been indicated as a relevant test to determine peripheral nerve injury level and severity.23 However, the feasibility of this test may be limited due to its considerable cost, need for a skilled physician, and the inherent risk of an invasive test.24 NED can also be diagnosed by SET, which presents sensitivity ranging from 88% to 100% compared to needle electromyography.21 The chronaxie needs to be considered in the proposal of NMES protocols for experimental and rehabilitation purposes.21,24,25 In addition, a possible mechanism for non-responsivity to NMES parameters has not yet been elucidated after SCI.
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
Compensatory Strategies Due to Knee Flexion Constraint during Gait of Non-Disabled Adults
Published in Journal of Motor Behavior, 2022
Odair Bacca, Melissa Leandro Celestino, José Angelo Barela, Sergiy Yakovenko, Ana Júlia Silva de Lima, Ana Maria Forti Barela
The motion of lower limbs was tracked using reflective markers placed bilaterally on the anterior and posterior superior iliac crest, lateral and medial femoral epicondyle, tibialis tuberosity, lateral and medial malleolus, inter malleolus, calcaneus, and first and fifth metatarsal head. Additionally, rigid clusters with non-collinear reflective markers were placed on the sacrum, thighs, and shanks. Passive disposable dual Ag/AgCl electrodes, each with circular conductive area having a 1-cm diameter and a 2-cm center-to-center distance, were placed bilaterally on the belly of the following muscles: rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), tibialis anterior (TA), semitendinosus (ST), biceps femoris long head (BF), gastrocnemius medialis (GM), and gastrocnemius lateralis (GL) and connected to double-differential preamplifiers (dual electrode, Noraxon, Inc.). The placement of electrodes followed the guidelines of the Surface Electromyographic for Noninvasive Assessment of Muscles (SENIAM) (Hermens et al., 2000). Electrode and wire leads were secured with elastic bands to diminish the motion artifacts.