Which of the following presents with hyperthermia and lead-pipe rigidity as a hallmark feature?

• A. Neuroleptic malignant syndrome
• B. Extrapyramidal symptoms
• C. Serotonin syndrome
• D. Parkinson's disease

Answer: (A)

Hyperthermia with lead-pipe rigidity is the hallmark of neuroleptic malignant syndrome, a rare, life-threatening reaction to dopamine D2 antagonists (typical antipsychotics) or to withdrawal of dopaminergic therapy. The rigidity is described as uniform and very hard to move (lead-pipe), and it accompanies high fever and autonomic instability, often with altered mental status. Lab clues like a markedly elevated creatine kinase reflect muscle breakdown.

This combination helps distinguish it from other options. Extrapyramidal symptoms are movement disorders from antipsychotics but typically lack the severe hyperthermia and autonomic crisis. Serotonin syndrome can also involve high fever but usually shows neuromuscular hyperactivity such as clonus and hyperreflexia rather than predominant lead-pipe rigidity. Parkinson's disease is a chronic neurodegenerative condition with tremor and bradykinesia, not an acute hyperthermic crisis.