Which statement best describes neuromuscular blockade in myasthenia gravis?

Which statement best describes neuromuscular blockade in myasthenia gravis?

• A. Increased sensitivity to succinylcholine
• B. Resistance to succinylcholine and increased sensitivity to nondepolarizing NMB
• C. Increased resistance to nondepolarizing NMB
• D. No change in response to NMB

Answer: (B)

In myasthenia gravis there are fewer functional nicotinic acetylcholine receptors at the neuromuscular junction because of autoimmune destruction. Nondepolarizing neuromuscular blockers work by competitively blocking those receptors, so with fewer receptors available, a given dose produces a stronger and more prolonged blockade. That makes patients with MG unusually sensitive to nondepolarizing NMBs. On the other hand, depolarizing blockers like succinylcholine rely on enough receptors to generate multiple rounds of depolarization; with fewer receptors, its effect is blunted, leading to resistance to succinylcholine. In practice, this means MG patients typically require smaller doses of nondepolarizing NMBs and may be relatively resistant to succinylcholine, with neuromuscular monitoring guiding dosing.

In myasthenia gravis there are fewer functional nicotinic acetylcholine receptors at the neuromuscular junction because of autoimmune destruction. Nondepolarizing neuromuscular blockers work by competitively blocking those receptors, so with fewer receptors available, a given dose produces a stronger and more prolonged blockade. That makes patients with MG unusually sensitive to nondepolarizing NMBs. On the other hand, depolarizing blockers like succinylcholine rely on enough receptors to generate multiple rounds of depolarization; with fewer receptors, its effect is blunted, leading to resistance to succinylcholine. In practice, this means MG patients typically require smaller doses of nondepolarizing NMBs and may be relatively resistant to succinylcholine, with neuromuscular monitoring guiding dosing.