A 65-year-old woman with known Myasthenia Gravis (MG) presents to the ICU with respiratory failure. She was started on ciprofloxacin 3 days ago for a UTI. She is intubated. Which aspect of her management is MOST critical?
- A Identify and stop the precipitating drug (ciprofloxacin); initiate plasma exchange or IVIg ✓
- B Start pyridostigmine at high doses immediately
- C Administer edrophonium test to distinguish myasthenic from cholinergic crisis
- D Begin corticosteroids immediately at high dose
Explanation
In myasthenic crisis, precipitating drugs must be identified and stopped. Fluoroquinolones (ciprofloxacin, levofloxacin) can precipitate MG exacerbation. Plasma exchange (PLEX) and IVIg are the treatments of choice in crisis, with comparable efficacy; PLEX acts faster (benefit within 3–5 days). Pyridostigmine is withheld in crisis because it increases secretions and may worsen respiratory failure. The edrophonium (Tensilon) test for crisis differentiation is no longer standard practice. High-dose corticosteroids can initially worsen MG and are not the acute crisis treatment.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.