What is the diagnosis for a patient with fever, muscle rigidity, altered mental status, and autonomic dysfunction, currently on risperidone (antipsychotic medication) and recently treated with electroconvulsive therapy (ECT) and metoclopramide (antiemetic medication)?

Diagnosis: Neuroleptic Malignant Syndrome

This patient has neuroleptic malignant syndrome (NMS), characterized by the classic tetrad of hyperthermia (102.5°F), muscle rigidity (symmetric rigidity of extremities), altered mental status (stuporous, responds weakly), and autonomic dysfunction (tachycardia, hypertension, diaphoresis) in the setting of antipsychotic exposure (risperidone). 1, 2

Clinical Reasoning

Why NMS is the Correct Diagnosis

The patient presents with all cardinal features of NMS as defined by the American Academy of Pediatrics and FDA guidelines:

• Hyperthermia: Temperature of 102.5°F meets the diagnostic threshold (>100.4°F) 1, 3
• Muscle rigidity: Symmetric rigidity of upper and lower extremities with decreased reflexes represents the "lead pipe rigidity" characteristic of NMS 1, 2
• Altered mental status: Stuporous state with weak response to verbal stimuli indicates severe mental status changes ranging from delirium to stupor 1, 2
• Autonomic instability: Tachycardia (pulse 120), hypertension (170/105), and diaphoresis demonstrate sympathetic nervous system lability 1, 2
• Antipsychotic exposure: Currently on risperidone, which is strongly associated with NMS and can cause extrapyramidal side effects more than other atypical antipsychotics 4, 3

Additional Supporting Evidence

• Leukocytosis: WBC of 12,700 is consistent with NMS (typical range 15,000-30,000, though can be lower) 1, 2
• Metoclopramide contribution: This dopamine antagonist antiemetic can precipitate or worsen NMS, particularly when combined with other antipsychotics 5
• ECT as risk factor: Recent ECT treatment may have contributed as a physiological stressor 1

Why Other Diagnoses Are Excluded

Meningitis (Option A) - Incorrect

• While fever and altered mental status are present, the symmetric muscle rigidity with decreased reflexes is inconsistent with meningitis, which typically causes meningismus (neck stiffness) rather than generalized lead pipe rigidity 4
• The clinical context of recent antipsychotic and metoclopramide use strongly points away from infection 4

Malignant Hyperthermia (Option B) - Incorrect

• Malignant hyperthermia is triggered by anesthetic agents (succinylcholine, halothane), not antipsychotics 4
• While ECT was performed, there is no mention of triggering anesthetic agents, and the syndrome developed hours after returning to the ward, not immediately during/after anesthesia 4
• The mechanism differs: malignant hyperthermia involves dysregulation of calcium in skeletal muscle from genetic susceptibility to anesthetics, whereas NMS involves central dopamine blockade 4, 2

Serotonin Syndrome (Option D) - Incorrect

• Serotonin syndrome is distinguished by hyperreflexia, clonus, and myoclonus, not the decreased reflexes and lead pipe rigidity seen here 4, 2
• This patient has decreased reflexes, which is characteristic of NMS, not serotonin syndrome 4
• While hydroxyzine has mild serotonergic properties, the clinical picture does not fit: serotonin syndrome typically presents with hyperreflexia and spontaneous or inducible clonus 4

Diagnostic Scoring

Using the American Academy of Pediatrics point-based diagnostic system for NMS (≥76 points indicates probable NMS): 1

• Dopamine antagonist exposure (risperidone + metoclopramide): 20 points
• Hyperthermia (>100.4°F): 18 points
• Rigidity: 17 points
• Mental status alteration: 13 points
• Sympathetic nervous system lability (tachycardia, hypertension, diaphoresis): 10 points
• Leukocytosis present: supports diagnosis
• Total: 78 points = Probable NMS 1

Critical Clinical Pearls

• Metoclopramide is a known precipitant of NMS due to its dopamine antagonist properties, and this case represents the additive effect with risperidone 5
• Risperidone carries higher risk for extrapyramidal side effects and NMS among atypical antipsychotics 4, 3
• The FDA label for risperidone explicitly warns that it "can cause a potentially fatal symptom complex referred to as Neuroleptic Malignant Syndrome" with the exact clinical manifestations present in this patient 3
• Decreased reflexes are a key distinguishing feature from serotonin syndrome, which presents with hyperreflexia 4

Immediate Management Required

All antipsychotic medications and metoclopramide must be discontinued immediately 1, 2, 3

Additional urgent interventions include:

• Aggressive IV hydration for dehydration and potential rhabdomyolysis (elevated potassium suggests muscle breakdown) 1, 2
• Benzodiazepines as first-line for agitation 1, 2
• External cooling measures for hyperthermia 1, 2
• Monitor creatine kinase levels (not provided but likely elevated) 1, 2
• Monitor for renal failure given electrolyte abnormalities 1, 2

Answer: C. Neuroleptic Malignant Syndrome