Reversible spontaneous EMG activity during myasthenic crisis: Two case reports

Abstract

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.

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

“…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.…”

Myasthenia gravis masquerading as amyotrophic lateral sclerosis: a case report

“…8 In this case report we present a rare manifestation of MG. Spontaneous electromyography activity was also present however traditionally is not expected in neuromuscular junction disorders. 9 Nevertheless, MG was diagnosed, and patient received treatment plan with Pyridostigmine and Prednisolone which initially had a positive impact until symptom reoccurrence. Further examination revealed more uncommon subtype of disease -MuSK-MG which required additional immunotherapy in order to provide adequate symptom control.…”