What are the key clinical features to recognize Neuroleptic Malignant Syndrome (NMS) in a patient on antipsychotic medication?

Key clinical features to recognize Neuroleptic Malignant Syndrome (NMS) in a patient receiving antipsychotic medication include:

• Hyperthermia: A high fever is a hallmark feature, often exceeding 38°C, reflecting the systemic inflammatory response ².
• Muscle rigidity: Severe, generalized 'lead-pipe' rigidity is characteristic and differentiates NMS from other conditions ¹.
• Autonomic dysfunction: Manifested by labile or elevated blood pressure, tachycardia, diaphoresis, and tachypnoea ².
• Altered mental status: Ranging from agitation and confusion to stupor and coma, indicating central nervous system involvement ¹.
• Elevated creatine kinase (CK): Marked elevation due to muscle breakdown supports the diagnosis, although this is a laboratory rather than clinical feature (Mooney and Hasan, 1990).
• Other features: May include leukocytosis and metabolic acidosis ¹.

Recognition requires a high index of suspicion in any patient on antipsychotics presenting with this constellation of symptoms, as early diagnosis and management are critical ². While atypical antipsychotics may present with a somewhat atypical or less severe syndrome, the core features remain consistent (Odagaki, 2009).