What symptom indicates Neuroleptic Malignant Syndrome (NMS)?

Neuroleptic Malignant Syndrome (NMS) is a serious and potentially life-threatening reaction that can occur in individuals taking antipsychotic medications, also known as neuroleptics. One of the hallmark symptoms of NMS is severe muscle rigidity. This rigidity is often described as "lead-pipe" in nature and can be accompanied by other symptoms such as hyperthermia, autonomic instability, and altered mental status.

The presence of muscle rigidity distinguishes NMS from other conditions that might involve similar symptoms, thereby enabling accurate diagnosis and prompt treatment. Recognizing this symptom is crucial for healthcare professionals since NMS can develop rapidly and requires immediate medical intervention.

Other symptoms mentioned in the choices, such as severe headache, anxiety, and dry mouth, do not specifically indicate NMS and can occur in a variety of other medical conditions or situations. Therefore, muscle rigidity is the most indicative symptom of Neuroleptic Malignant Syndrome and is key to identifying this critical syndrome in patients on antipsychotic therapy.