scholarly journals Pseudomyopathic Changes in Needle Electromyography in Lambert-Eaton Myasthenic Syndrome

2013 ◽  
Vol 2013 ◽  
pp. 1-2 ◽  
Author(s):  
Teppei Komatsu ◽  
Kota Bokuda ◽  
Toshio Shimizu ◽  
Tetsuo Komori ◽  
Reiji Koide
Keyword(s):  
Nerve Stimulation ◽  
Compound Muscle Action Potential ◽  
The Other ◽  
Motor Unit Potential ◽  
Muscle Action ◽  
Repetitive Nerve Stimulation ◽  
Needle Electromyography ◽  
Muscle Action Potential ◽  
Myasthenic Syndrome ◽  
Myopathic Changes

Lambert-Eaton myasthenic syndrome (LEMS) is a rare presynaptic disorder of the neuromuscular junction in association with cancer and subsequently in cases in which no neoplasm has been detected (O’Neill et al., 1988). The diagnosis of LEMS is based on the combination of fluctuating muscle weakness, diminished or absent reflexes, and a more than 60% increment of compound muscle action potential (CMAP) amplitude after brief exercise or 50 Hz stimulation for 1 s in a repetitive nerve stimulation (RNS) test (Oh et al., 2005). On the other hand, needle electromyography (EMG) findings related to LEMS have not been well described. Here, we report a case of LEMS, which showed apparent myopathic changes in needle EMG findings. Furthermore, we retrospectively examined the needle EMG findings in 8 patients with LEMS. In six of the 8 patients, the EMG findings showed myopathy-like findings. Although the findings of needle EMG indicated myopathic changes at a glance, the motor unit potential (MUP) returned to normal after a sustained strong muscle contraction. We propose the name “pseudomyopathic changes” for this phenomenon.

Congenital Myasthenic Syndrome: Presentation, Electrodiagnosis, and Muscle Biopsy

2004 ◽  
Vol 19 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Christina A. Gurnett ◽  
Judy A. Bodnar ◽  
Jeffrey Neil ◽  
Anne M. Connolly
Keyword(s):  
Action Potential ◽  
Nerve Stimulation ◽  
Compound Muscle Action Potential ◽  
Muscle Action ◽  
Repetitive Nerve Stimulation ◽  
Poor Growth ◽  
Congenital Myasthenic Syndromes ◽  
Feeding Difficulties ◽  
Muscle Action Potential ◽  
Myasthenic Syndromes

We report 10 children with congenital myasthenic syndromes diagnosed by clinical features, electrodiagnostic studies, and response to acetylcholinesterase inhibitors. Age at diagnosis (mean = 4.4 years; range 0.2–10 years) correlated with age fatigue was recognized. Symptoms at presentation included mild gross motor development delay (7/10), speech articulation difficulty (5/10), and respiratory and feeding difficulties resulting in poor growth in 7 of 10 children. None of the five children with possible presynaptic abnormalities had decremental compound muscle action potential responses to 2 Hz repetitive nerve stimulation. Instead, electrodiagnostic studies showed a more than 100% increment of compound muscle action potential amplitude during 50 Hz repetitive nerve stimulation in two children and sustained compound muscle action potential decrement to 2 Hz repetitive nerve stimulation after depletion (10 Hz stimulation for 10 min) in four children. Muscle biopsies ( n = 7) showed mild to severe variation in fiber size. Our experience suggests that many children with congenital myasthenic syndromes might be undiagnosed because of atypical presentation and because additional electrophysiologic studies are required.

Congenital Myasthenic Syndrome: Presentation, Electrodiagnosis, and Muscle Biopsy

2004 ◽  
Vol 19 (3) ◽  
pp. 175-182
Author(s):  
Christina A. Gurnett ◽  
Judy A. Bodnar ◽  
Jeffrey Neil ◽  
Anne M. Connolly
Keyword(s):  
Action Potential ◽  
Nerve Stimulation ◽  
Compound Muscle Action Potential ◽  
Muscle Action ◽  
Repetitive Nerve Stimulation ◽  
Poor Growth ◽  
Congenital Myasthenic Syndromes ◽  
Feeding Difficulties ◽  
Muscle Action Potential ◽  
Myasthenic Syndromes

We report 10 children with congenital myasthenic syndromes diagnosed by clinical features, electrodiagnostic studies, and response to acetylcholinesterase inhibitors. Age at diagnosis (mean = 4.4 years; range 0.2–10 years) correlated with age fatigue was recognized. Symptoms at presentation included mild gross motor development delay (7/10), speech articulation difficulty (5/10), and respiratory and feeding difficulties resulting in poor growth in 7 of 10 children. None of the five children with possible presynaptic abnormalities had decremental compound muscle action potential responses to 2 Hz repetitive nerve stimulation. Instead, electrodiagnostic studies showed a more than 100% increment of compound muscle action potential amplitude during 50 Hz repetitive nerve stimulation in two children and sustained compound muscle action potential decrement to 2 Hz repetitive nerve stimulation after depletion (10 Hz stimulation for 10 min) in four children. Muscle biopsies ( n = 7) showed mild to severe variation in fiber size. Our experience suggests that many children with congenital myasthenic syndromes might be undiagnosed because of atypical presentation and because additional electrophysiologic studies are required.

Pathophysiological associations in paediatric neuromuscular junction disorders

2017 ◽  
Author(s):  
Matthew Pitt
Keyword(s):  
Neuromuscular Junction ◽  
Nerve Stimulation ◽  
High Frequency ◽  
Compound Muscle Action Potential ◽  
Paediatric Population ◽  
Neuromuscular Blocking ◽  
Repetitive Nerve Stimulation ◽  
Long Duration ◽  
Muscle Action Potential ◽  
Autoimmune Conditions

Myasthenia can be caused by acquired or autoimmune conditions and other conditions resulting from genetic abnormalities of the proteins in the neuromuscular junction. The clinical clues to diagnosis in the paediatric population are highlighted in this chapter. Among these are sudden death, episodic apnoea, stridor, association with myopathy, and limb-girdle weakness presentation. Acquired disorders of the neuromuscular junction occur, such as infantile botulism, tick paralysis, and persistence of neuromuscular blocking agents. Some patterns of abnormality are seen in the neurophysiological findings, the most notable of which is a repetitive compound muscle action potential at low rates of stimulation. Decrement only seen after long-duration, high-frequency repetitive nerve stimulation is described in choline acetyltransferase (CHAT) abnormalities. DOK7 myasthenia may demonstrate patchy abnormalities of jitter and this is described along with the profound increment of the high-frequency repetitive nerve stimulation in Lambert–Eaton syndrome.

scholarly journals Estimation of Median Nerve Axonal Degeneration without Needle Electromyography

2021 ◽  
Vol 7 (1) ◽  
pp. 23-30
Author(s):  
Mozaffar Hosseininezhad ◽  
◽  
Amir Reza Ghayeghran ◽  
Paria Nasiri ◽  
Sajjad Saadat ◽  
...  
Keyword(s):  
Median Nerve ◽  
Nerve Stimulation ◽  
Compound Muscle Action Potential ◽  
Axonal Loss ◽  
Abductor Pollicis Brevis ◽  
Needle Electromyography ◽  
Median Nerve Stimulation ◽  
Muscle Action Potential ◽  
Stimulation Tests ◽  
Tunnel Syndrome

Background and Aim: The present study aimed to use the median nerve Compound Muscle Action Potential (CMAP) amplitude by stimulation at the palm instead of Abductor Pollicis Brevis (APB) needle Electromyography (EMG) for determining axonal loss in patients with Carpal Tunnel Syndrome (CTS). Methods and Materials/Patients: This study was performed on 180 patients with CTS referred to the Electrodiagnostic (EDX) Center, Poursina Hospital, Guilan Province, Iran, in 2018-19. In this study, the APB needle EMG diagnostic test was used as the gold standard, and median nerve CMAP amplitude with stimulation at the palm and wrist were used to compare the two nerve stimulation tests. Results: All of the cases with abnormal amplitude loss detected by median nerve stimulation at the palm also had an axonal loss in the needle EMG of APB. So this test could be a good indicator of axonal loss if there is an abnormality (sensitivity: 73%, specificity: 100%). The results with wrist stimulation were not as accurate as of the palm stimulation, and some cases with decreased CMAP amplitude of median nerve had normal needle EMG of APB muscle (sensitivity: 86.6%, specificity: 94.9%). Conclusion: In cases with CTS, the abnormally decreased amplitude of the median nerve detected by stimulation at the palm could be a good indicator of axonal loss.

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