What condition is Neuroleptic Malignant Syndrome associated with?

Neuroleptic Malignant Syndrome (NMS) is a serious and potentially life-threatening reaction that can occur in response to antipsychotic medications, particularly the typical neuroleptics. One of the hallmark features of NMS is hyperprexia, which refers to an extreme elevation in body temperature, typically exceeding 38°C (100.4°F) and often reaching dangerous levels.

This hyperthermia results from a dysregulation of the body's thermoregulatory system, often accompanying other signs such as muscle rigidity, altered mental status, and autonomic dysregulation. The development of hyperprexia in NMS is critical as it can lead to severe complications, including multi-organ failure if not promptly identified and treated.

The other conditions listed do not directly relate to the symptoms or pathophysiology of NMS. Severe dehydration can have its complications but is not a defining characteristic of NMS. Severe headache and rapid weight gain are also not typical features of this syndrome. Thus, hyperprexia appropriately identifies a key diagnostic criterion for Neuroleptic Malignant Syndrome.