a) List the disease specific interventions for a severe myasthenic crisis in a patient who is invasively ventilated. (50% marks)
b) List four classes of drugs with the potential to exacerbate a myasthenic crisis. (20% marks)
c) Discuss the challenges for a successful extubation in a patient specifically after a myasthenic crisis. Your answer should include methods to address the challenges. (30% marks)
Most candidates had a superficial understanding of myaesthenia gravis and myaesthenic crisis. Candidates who scored well were familiar with the pathogenesis of the disease and the triggers and treatments. However, even those candidates who referred to specific challenges such as fatiguability, bulbar dysfunction and secretion burden in the management section, often did not give a detailed discussion of how to manage these. Most candidates mentioned pyridostigmine and/or neostigmine, IVIG, plasma exchange, steroids and/or other immunosuppressants, and therefore scored well for part (a) (which was worth 50%).
They said "list" the interventions, a syllabus keyword which conventionally does not invite very much discussion; and for 30% of the marks you'd really only be expected to produce a short point-form list:
The list of drug classes that exacerbate myasthenia gravis include multiple different antibiotic classes, which - presumably- would have all counted individually
There is also a list of miscellaneous classless drugs that can trigger myasthenia exacerbations, and it is not clear what would have happened if the trainees had mentioned these:
An excellent paper on weaning the patient with neuromuscular disease was published by Torres-Castro et al in 2021, and likely served as the origin for this SAQ. Even though they did not find any papers that fit their inclusion criteria, they discuss the options in some detail, and the ideas in that paper were amalgamated into the table above.
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Schroeter, Michael, Günther Thayssen, and Julia Kaiser. "Myasthenia gravis–exacerbation and crisis." Neurology International Open 2.01 (2018): E10-E15.
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Dhawan, Priya S., et al. "IVIG versus PLEX in the treatment of worsening myasthenia gravis: what is the evidence?: a critically appraised topic." The neurologist 19.5 (2015): 145-148.
Farrugia, Maria Elena, and John A. Goodfellow. "A practical approach to managing patients with Myasthenia Gravis—Opinions and a review of the literature." Frontiers in Neurology 11 (2020): 604.
Torres-Castro, Rodrigo, et al. "Weaning from mechanical ventilation in people with neuromuscular disease: a systematic review." BMJ open 11.9 (2021): e047449.
Kim, Sun Mi, et al. "Successful extubation after weaning failure by noninvasive ventilation in patients with neuromuscular disease: case series." Annals of Rehabilitation Medicine 41.3 (2017): 450-455.