Vancouver IM LMR

Reference slides for myasthenia gravis

Resource: AAN Continuum Article on Diagnosis and Management of Myasthenia Gravis

Key points from today’s teaching:

1. Thoroughly question and characterize unclear presenting complaints eg “weakness” “inability to ambulate” (also – “altered” “dizzy”)
2. If you’re asking yourself “should I do a neuro exam”, do a neuro exam
3. Key physical findings in MG include ocular findings (ptosis/diplopia esp with sustained upgaze/other EOM movement, curtain sign, Cogan eyelid twitch, ice pack test), bulbar findings (one breath count, neck flexors), fatigable proximal muscle weakness
4. Myasthenia gravis crisis/impending crisis is a medical emergency, and requires quantification of respiratory strength with a view to possible definitive airway management (FVC 60cc/kg normal, <30 cc/kg ICU monitoring, <15 cc/kg intubate) + up front PLEX/IVIG (PLEX ~faster onset to action if you have a choice. Pyridostigmine and corticosteroids are NOT STARTED in crisis (pyridostigmine = cholinergic, worse resp secretions; steroids = transient worsening of weakness in first 5-7 days)
5. Remember meds to avoid in MG (IV magnesium, immune checkpoint inhibitors, mod risk with some antibiotic classes)