Paeds Vivas · neurology-neurodisability-and-neuromuscular
Myasthenia gravis and neuromuscular junction disorders: Viva
Branching clinical structured oral on paediatric myasthenia gravis and neuromuscular junction disorders covering the fatigable fluctuating weakness with preserved reflexes and pupils, the acetylcholine receptor and muscle-specific kinase and LRP4 antibody subtypes and the congenital myasthenic syndromes, the complement-mediated postsynaptic injury, the ice pack test and repetitive nerve stimulation and single-fibre neurophysiology, pyridostigmine dosing, the corticosteroid transient worsening with early steroid-sparing, the intravenous immunoglobulin and plasma exchange for crisis, thymectomy after the MGTX trial, eculizumab for refractory disease, the forced vital capacity thresholds for intensive care, the subtype-specific treatment of the congenital myasthenic syndromes, and the maternal antibody syndromes.
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Branch 1: Making the diagnosis
A strong candidate recognises this as autoimmune myasthenia gravis on the clinical picture alone, before the tests return. The diagnosis turns on the fatigability, the fluctuation, and the preservation of the reflexes and the pupils, rather than on a single test. The girl has fluctuating, fatigable weakness of the ocular, bulbar, and proximal muscles that worsens through the day and recovers with rest, the deep tendon reflexes and the pupils are spared, and the ice pack test lifts the ptotic eyelid within two minutes. The antibody panel with the acetylcholine receptor and the muscle-specific kinase antibodies and the repetitive nerve stimulation confirm the diagnosis, but the acetylcholine receptor antibody is negative in around twenty percent of generalised disease, so a negative result never excludes the diagnosis in a typical picture. [1]
References6ShowHide
- [1]Gilhus NE Myasthenia Gravis. N Engl J Med, 2016.PMID 28029925
- [2]Narayanaswami P, Sanders DB, Wolfe G, et al International Consensus Guidance for Management of Myasthenia Gravis: 2020 Update. Neurology, 2021.PMID 33144515
- [4]Wolfe GI, Kaminski HJ, Aban IB, et al Randomized Trial of Thymectomy in Myasthenia Gravis. N Engl J Med, 2016.PMID 27509100
- [5]Gajdos P, Chevret S, Toyka KV Intravenous immunoglobulin for myasthenia gravis. Cochrane Database Syst Rev, 2012.PMID 23235588
- [9]Engel AG, Shen XM, Selcen D, Sine SM Congenital myasthenic syndromes: pathogenesis, diagnosis, and treatment. Lancet Neurol, 2015.PMID 25792100
- [11]Guptill JT, Sanders DB Update on muscle-specific tyrosine kinase antibody positive myasthenia gravis. Curr Opin Neurol, 2010.PMID 20613516