PCP overdose can mimic which syndrome due to elevated CPK and autonomic instability?

• A. Serotonin syndrome
• B. Neuroleptic malignant syndrome
• C. Malignant hyperthermia
• D. Parkinsonism

Answer: (B)

Overdose with PCP can imitate neuroleptic malignant syndrome because both conditions can produce severe autonomic instability and a high CPK from rhabdomyolysis, along with Hyperthermia and dramatic mental status changes. Neuroleptic malignant syndrome arises mainly from dopamine D2 blockade by antipsychotics, leading to marked muscle rigidity (often described as lead-pipe rigidity), profound autonomic disruption, and high fever, with CPK elevation reflecting muscle breakdown. PCP, a dissociative agent, can trigger intense motor activity and hyperadrenergic responses that mimic this same pattern, including the muscle stress that drives CPK up.

Distinguishing features help: serotonin syndrome, while it can also cause fever and autonomic instability, typically shows clonus and hyperreflexia rather than the prominent rigidity of NMS. Malignant hyperthermia occurs in the context of anesthesia with a rapid, life-threatening hypermetabolic crisis. Parkinsonism is a chronic movement disorder with resting tremor and rigidity that does not present acutely with autonomic instability or dramatic CPK elevation.