Which disease is associated with increased resistance to neuromuscular blockade with succinylcholine?

Which disease is associated with increased resistance to neuromuscular blockade with succinylcholine?

• A. Myasthenia gravis
• B. Myasthenic syndrome
• C. Huntington's chorea
• D. Duchenne muscular dystrophy

Answer: (A)

Succinylcholine produces its block by depolarizing the nicotinic ACh receptors at the neuromuscular junction. In myasthenia gravis, autoimmune destruction reduces the number of functional postsynaptic ACh receptors. With fewer receptors available, the same amount of succinylcholine has fewer targets to activate, so the depolarizing effect is blunted and resistance to the blockade occurs. Clinically, this means MG patients are relatively less responsive to succinylcholine and may require adjustment or alternative strategies, even though they may be more sensitive to nondepolarizing agents due to the same receptor shortage. In contrast, Duchenne muscular dystrophy involves upregulation of extrajunctional receptors, which can cause dangerous hyperkalemia with succinylcholine rather than predictable resistance; the other conditions don’t produce the same loss of postsynaptic receptors that leads to this depolarizing-block resistance.

Succinylcholine produces its block by depolarizing the nicotinic ACh receptors at the neuromuscular junction. In myasthenia gravis, autoimmune destruction reduces the number of functional postsynaptic ACh receptors. With fewer receptors available, the same amount of succinylcholine has fewer targets to activate, so the depolarizing effect is blunted and resistance to the blockade occurs. Clinically, this means MG patients are relatively less responsive to succinylcholine and may require adjustment or alternative strategies, even though they may be more sensitive to nondepolarizing agents due to the same receptor shortage. In contrast, Duchenne muscular dystrophy involves upregulation of extrajunctional receptors, which can cause dangerous hyperkalemia with succinylcholine rather than predictable resistance; the other conditions don’t produce the same loss of postsynaptic receptors that leads to this depolarizing-block resistance.