Which agent can cause fasciculations?

• A. Vecuronium
• B. Rocuronium
• C. Cisatracurium
• D. Succinylcholine

Answer: (D)

Fasciculations come from the depolarizing action at the neuromuscular junction. Succinylcholine binds to nicotinic acetylcholine receptors and keeps them open, causing an initial burst of repeated muscle fiber contractions before the endplate becomes desensitized and paralysis sets in. This early, brief twitching is the fasciculation. The other agents listed are nondepolarizing blockers; they simply prevent acetylcholine from activating the receptor without causing the initial depolarization, so they do not produce fasciculations. Thus, succinylcholine is the one that can cause fasciculations.