Which feature is more characteristic of serotonin syndrome than NMS?

Which feature is more characteristic of serotonin syndrome than NMS?

• A. Hyperreflexia
• B. Muscle rigidity
• C. Slow onset
• D. Normal reflexes

Answer: (A)

Hyperreflexia is more characteristic of serotonin syndrome than NMS because excess serotonin causes neuromuscular hyperreactivity, often with clonus and rapidly increasing reflex responses after exposure to serotonergic medications. Neuroleptic malignant syndrome, on the other hand, is driven by dopamine blockade and presents with severe muscle rigidity and usually normal or reduced reflexes, developing more slowly over days. So the presence of increased reflexes (hyperreflexia) points to serotonin syndrome, while muscle rigidity and a slower onset fit NMS.