A patient on an inpatient psychiatric unit presents with a sudden high fever. The nurse suspects neuroleptic malignant syndrome because the patient also has the following symptoms:

Choice A reason: Elevated liver enzymes may occur with certain psychotropic medications but are not diagnostic of neuroleptic malignant syndrome (NMS). They are nonspecific and not part of the classic NMS presentation. Choice B reason: Lead pipe rigidity and autonomic instability (e.g., fluctuating blood pressure, tachycardia, diaphoresis) are hallmark signs of NMS. Combined with hyperthermia, these symptoms indicate a life-threatening reaction to antipsychotic medications. Choice C reason: Headache and increased intracranial pressure are neurological symptoms unrelated to NMS. They may suggest other conditions such as meningitis or intracranial hemorrhage. Choice D reason: Agranulocytosis is a serious adverse effect of clozapine, not typical of NMS. It involves neutropenia and infection risk, not muscular rigidity or autonomic dysfunction.