A 42-year-old woman with myasthenia gravis on pyridostigmine requires thymectomy. Which neuromuscular blocking pattern is expected?

• A Increased sensitivity to both depolarising and non-depolarising blockers
• B Resistance to succinylcholine requiring higher doses, and exaggerated sensitivity to rocuronium requiring lower doses ✓
• C Normal response to all relaxants because pyridostigmine restores receptor density
• D Resistance to rocuronium and sensitivity to succinylcholine

Explanation

Autoimmune loss of nicotinic receptors leaves fewer receptors for succinylcholine to occupy, so patients show resistance and may need up to twice the usual dose for intubation. Conversely, the reduced receptor reserve makes them markedly sensitive to non-depolarising agents such as rocuronium and vecuronium, whose doses are typically reduced by half or more with careful monitoring. Pyridostigmine also prolongs the action of ester-based relaxants. Option D reverses the true pattern.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.