Abnormal spontaneous activity on needle electromyography in myasthenia gravis

Kannaditharayil, Deepa; Napier, Fabreena; Granit, Volkan; Bieri, Phyllis; Herskovitz, Steven

doi:10.1002/mus.25615

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…These studies are in line with previously published data describing findings compatible with neuromuscular junction involvement in up to 50% rate of the cases [7,13]. Remarkably, all the patients with generalized myasthenia in our series displayed a myopathic pattern with mild spontaneous activity in proximal muscles, which is a finding also described in classic MG [31,32]. These findings can be difficult to differentiate from myositis, and for this reason we have not relied solely on EDX findings to diagnose an immune-mediated myopathy.…”

Section: Discussionsupporting

confidence: 93%

Myasthenia Gravis Induced by Immune Checkpoint Inhibitors: An Emerging Neurotoxicity in Neuro-Oncology Practice: Case Series

Marco

Simó

Alemany

et al. 2022

JCM

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Immunotherapy with immune checkpoint inhibitors (ICIs) have been reported to induce de novo or exacerbate pre-existing Myasthenia Gravis (MG). We present a single center case series of patients who developed an immune-related myasthenia gravis (irMG) related with ICIs. We performed a retrospective chart review of the electronic medical records between 1 September 2017 and 2022. We report the clinical features, presentation forms, diagnostic workflows, general management and outcomes of six patients who received ICIs for different solid organ malignancies and developed an irMG frequently overlapping with immune-related myocarditis and/or myositis. The aim of the article is to describe the clinical features, treatment and outcomes of this challenging and potentially life-threating syndrome, comparing our data with those described in the literature. Differences between irMG and classic MG are highlighted.

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Section: Discussionsupporting

confidence: 93%

Myasthenia Gravis Induced by Immune Checkpoint Inhibitors: An Emerging Neurotoxicity in Neuro-Oncology Practice: Case Series

Marco

Simó

Alemany

et al. 2022

JCM

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“…Spontaneous EMG activity is traditionally considered inconsistent with pure NMJ disorders. However there are few reports that disproved that notion on clinical [ [22] , [23] , [24] , [25] ] and experimental grounds [ 26 ]. Besides spontaneous EMG activity is a well-appreciated potential finding in cases of botulism [ 27 , 28 ].…”

Section: Introductionmentioning

confidence: 99%

Reversible spontaneous EMG activity during myasthenic crisis: Two case reports

Tsironis

Catania

2019

eNeurologicalSci

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BackgroundMyasthenia Gravis (MG) is an antibody-mediated autoimmune neuromuscular disorder, clinically presenting with fatigable variable muscle weakness. Typical electrodiagnostic findings are a decremental response to repetitive nerve stimulation with post-exercise facilitation, and motor unit instability expressed as increased jitter on single fibre-EMG. Presence of spontaneous activity on standard EMG is traditionally considered inconsistent with a diagnosis of MG and would direct the differential diagnosis towards a primary denervating or usually inflammatory myopathic process.Case reportWe herein present two patients with progressive severe bulbar symptomatology, whose needle-EMG examinations showed spontaneous activity and led to erroneous initial diagnoses of inflammatory myopathy and anterior horn cell disease respectively. Follow-up neurophysiological investigations, positive anti-AchR titres and good response to IVIg and steroids eventually established the diagnosis of Myasthenia Gravis.ConclusionsClinically severe Myasthenia Gravis can potentially present with spontaneous activity on EMG, mimicking acute myopathic or neurogenic processes. This can prove particularly perplexing and cause significant delays in the diagnosis and treatment of a myasthenia relapse.

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“…Functional denervation secondary to severe neuromuscular junction transmission defect can also cause spontaneous activity. 21,22 Myotonic discharges in paraspinal muscles might be the only electrodiagnostic abnormality in Pompe disease necessitating the needling of multiple paraspinal segments. 23 Often, an integration of all the electrophysiological parameters rather than a single test in isolation is required for reaching an accurate diagnosis.…”

Section: Considerations While Formulating An Electrodiagnostic Protocolmentioning

confidence: 99%

“De Novo” Hypercapnic Respiratory Failure Unmasking Neuromuscular Disorders: Experiences From a Tertiary Care Center and Review of Literature

Nair,

Kandagaddala,

Sivadasan

et al. 2024

Journal of Clinical Neuromuscular Disease

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Objectives: Neuromuscular disorders could have respiratory involvement early or late into illness. Rarely, patients may present with a hypercapnic respiratory failure (with minimal motor signs) unmasking an underlying disease. There are hardly any studies which have addressed the spectrum and challenges involved in management of this subset, especially in the real-world scenario. Methods: A retrospective study comprising consecutive patients hospitalized with hypercapnic respiratory failure as the sole/dominant manifestation. The clinical–electrophysiological spectrum, phrenic conductions, diaphragm thickness, and outcomes were analyzed. Results: Twenty-seven patients were included, the mean age was 47.29 (SD 15.22) years, and the median duration of respiratory symptoms was 2 months (interquartile range [IQR] 1–4). Orthopnea was present in 23 patients (85.2%) and encephalopathy in 8 patients (29.6%). Phrenic nerve latencies and amplitudes were abnormal in 83.3% and 95.6%, respectively. Abnormal diaphragm thickness was noted in 78.5%. Based on a comprehensive electrophysiological strategy and paraclinical tests, an etiology was established in all. Reversible etiologies were identified in 17 patients (62.9%). These included myasthenia gravis (anti-AChR and MuSK), inflammatory myopathy, riboflavin transporter deficiency neuronopathy, Pompe disease, bilateral phrenic neuritis, and thyrotoxicosis. Respiratory onset motor neuron disease was diagnosed in 8 patients (29.6%). Despite diaphragmatic involvement, a functional respiratory recovery was noted at discharge (45%) and last follow-up (60%). Predictors for good outcomes included female sex, normal nerve conductions, and recent-onset respiratory symptoms. Discussion: A good functional recovery was noted in most of the patients including respiratory onset motor neuron disease. A systematic algorithmic approach helps in proper triaging, early diagnosis, and treatment. Clinical and electrodiagnostic challenges and observations from a tertiary care referral center are discussed.

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Abnormal spontaneous activity on needle electromyography in myasthenia gravis

Cited by 7 publications

References 20 publications

Myasthenia Gravis Induced by Immune Checkpoint Inhibitors: An Emerging Neurotoxicity in Neuro-Oncology Practice: Case Series

Myasthenia Gravis Induced by Immune Checkpoint Inhibitors: An Emerging Neurotoxicity in Neuro-Oncology Practice: Case Series

Reversible spontaneous EMG activity during myasthenic crisis: Two case reports

“De Novo” Hypercapnic Respiratory Failure Unmasking Neuromuscular Disorders: Experiences From a Tertiary Care Center and Review of Literature

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