A nurse is assessing a client who recently began taking fluphenazine. Which of the following findings should the nurse identify as a neurologic manifestation of neuroleptic malignant syndrome?

Introduction: Neuroleptic malignant syndrome (NMS) is a rare, life-threatening idiosyncratic reaction to antipsychotic medications, characterized by dopamine blockade in the hypothalamus and basal ganglia, leading to autonomic instability and neuromuscular dysfunction. A. Muscle rigidity, often described as "lead-pipe" rigidity, is a hallmark neurologic manifestation of NMS. It results from profound dopamine depletion in the nigrostriatal pathway. This intense muscular contraction contributes to secondary complications such as rhabdomyolysis, elevated creatine kinase levels, and potential acute renal failure if not treated emergently. B. Hyperbilirubinemia is not a diagnostic finding or a neurologic manifestation associated with neuroleptic malignant syndrome. While NMS can affect multiple organ systems due to physiological stress, primary hepatic dysfunction or elevated bilirubin levels are not clinical markers used to identify this specific adverse reaction to neuroleptic agents. C. Decreased temperature is the opposite of what occurs in NMS. Clients typically experience profound hyperpyrexia, with temperatures often exceeding 38°C or even 40°C. This extreme fever is caused by hypothalamic thermoregulatory disruption and excessive heat production from continuous, severe muscle rigidity throughout the body. D. Bradycardia is inconsistent with the autonomic instability seen in NMS. Instead, clients typically exhibit significant tachycardia and labile blood pressure. The autonomic nervous system becomes severely dysregulated, leading to a hypermetabolic state characterized by rapid heart rates, tachypnea, and profuse diaphoresis as the body attempts to compensate.