What is the likely diagnosis for a patient receiving haloperidol who develops fever, muscle rigidity, and elevated creatine kinase levels?

• A. Catatonia
• B. Dystonia
• C. Malignant hyperthermia
• D. Neuroleptic malignant syndrome

Answer: (D)

The presentation of fever, muscle rigidity, and elevated creatine kinase levels in a patient receiving haloperidol is highly indicative of neuroleptic malignant syndrome (NMS). This condition is a serious and potentially life-threatening reaction to antipsychotic medications, particularly the typical antipsychotics like haloperidol.

NMS is characterized by a combination of autonomic instability, altered mental status, muscle rigidity, and hyperthermia. The muscle rigidity observed in NMS is often described as "lead-pipe" rigidity, and the elevated creatine kinase levels reflect muscle breakdown (rhabdomyolysis) due to the extreme rigidity and increased muscle activity. The high fever is a result of dysregulation of the hypothalamic thermoregulation associated with the syndrome.

Understanding the specific clinical features and the context in which they occur is key to diagnosing NMS. Other conditions mentioned, such as catatonia, dystonia, and malignant hyperthermia, do not present with the exact combination of symptoms seen in this case or are associated with different clinical contexts.

Thus, with a patient on haloperidol experiencing these symptoms, neuroleptic malignant syndrome is a likely diagnosis that requires immediate medical attention and intervention.