Emergency Medicine · Year 3 · from Emergency Medicine

Case 1: Neuroleptic Malignant Syndrome

Patient Demographics

  • Age: 34 years
  • Sex: Male
  • Occupation: Unemployed

Chief Complaint

"He's burning up and can't move his body right."

History of Present Illness

The patient is brought to the emergency department by his group home staff with 2 days of progressive symptoms. He was noted to have a fever yesterday morning and appeared increasingly confused and less responsive. Today he has become rigid and is minimally verbal. His temperature at the group home was measured at 104 degrees F. He has a history of schizophrenia and was started on haloperidol 10 mg twice daily approximately 10 days ago after a recent hospitalization for acute psychosis. He had been on risperidone previously but it was discontinued due to inadequate symptom control. His other medications include benztropine 1 mg twice daily.

Vital Signs

  • Temperature: 104.8 degrees F (40.4 degrees C)
  • Blood pressure: 168/102 mmHg
  • Heart rate: 124 bpm
  • Respiratory rate: 24/min
  • Oxygen saturation: 94% on room air

Physical Examination

General: Diaphoretic male, minimally responsive, eyes open but not tracking HEENT: Pupils 4 mm bilaterally, reactive; mucous membranes dry Cardiovascular: Tachycardic, regular rhythm, no murmurs Pulmonary: Tachypneic, clear to auscultation Abdomen: Decreased bowel sounds, soft, non-tender Neurological:

  • Mental status: Obtunded, does not follow commands, incomprehensible sounds only
  • Cranial nerves: Pupils reactive, corneal reflex present
  • Motor: Severe generalized rigidity throughout all extremities (lead-pipe rigidity)
  • No tremor, no clonus
  • Reflexes: Diminished throughout (2+ symmetric)
  • No focal deficits identified

Skin: Diaphoretic, no rash

Laboratory Findings

  • WBC: 16,800/microL
  • Hemoglobin: 15.8 g/dL (hemoconcentration)
  • Creatinine: 2.4 mg/dL (baseline unknown)
  • BUN: 38 mg/dL
  • Creatine Kinase: 18,450 U/L (markedly elevated)
  • AST: 286 U/L
  • ALT: 142 U/L
  • Sodium: 148 mEq/L
  • Potassium: 5.2 mEq/L
  • Lactate: 3.8 mmol/L
  • Urinalysis: Brown urine, positive for blood on dipstick, no RBCs on microscopy (consistent with myoglobinuria)

Additional Studies

  • CT Head without contrast: No acute intracranial abnormality
  • Lumbar puncture: Normal cell count, protein, glucose (ruling out meningitis)
  • Urine drug screen: Negative
  • Thyroid function tests: Normal

Diagnosis

Neuroleptic Malignant Syndrome (NMS) secondary to haloperidol

  • Rhabdomyolysis with acute kidney injury
  • Dehydration

Management

Immediate Actions:

  1. Discontinue haloperidol immediately
  2. Aggressive IV fluid resuscitation with normal saline (goal urine output >1 mL/kg/hr)
  3. Active cooling measures: ice packs to groin and axillae, cooling blanket
  4. Foley catheter for urine output monitoring
  5. Continuous cardiac monitoring
  6. ICU admission

Specific Pharmacotherapy:

  1. Dantrolene sodium 2 mg/kg IV bolus, then 1 mg/kg IV every 6 hours (direct skeletal muscle relaxant)
  2. Bromocriptine 2.5 mg via NG tube every 8 hours (dopamine agonist to restore dopaminergic tone)
  3. Lorazepam 2 mg IV every 6 hours PRN for agitation and to reduce rigidity

Supportive Care:

  1. DVT prophylaxis with sequential compression devices (avoid pharmacologic anticoagulation given rhabdomyolysis)
  2. Stress ulcer prophylaxis
  3. Serial CK monitoring every 6 hours
  4. Renal function monitoring
  5. Urine alkalinization if myoglobinuria persists

Hospital Course

  • Temperature normalized by day 3
  • CK peaked at 32,000 U/L on day 2, then declined
  • Rigidity gradually resolved over 5 days
  • Creatinine peaked at 3.1, improved to 1.4 by day 7
  • Mental status returned to baseline by day 6
  • Dantrolene and bromocriptine tapered over 10 days
  • Discharged on day 12 with outpatient psychiatry follow-up
  • Antipsychotic rechallenge deferred; if needed in future, will use low-potency atypical agent at lowest dose with close monitoring

Clinical Pearl

Neuroleptic malignant syndrome is an idiosyncratic reaction to dopamine-blocking agents, most commonly antipsychotics, but also antiemetics like metoclopramide. The four cardinal features are hyperthermia, lead-pipe rigidity, autonomic instability, and altered mental status. Unlike serotonin syndrome (which has rapid onset within hours and is characterized by clonus and hyperreflexia), NMS develops over days and features lead-pipe rigidity with diminished reflexes. The massively elevated CK from sustained muscle rigidity can cause acute kidney injury from myoglobin deposition. Treatment requires immediate discontinuation of the offending agent plus dantrolene (a direct muscle relaxant) and bromocriptine (a dopamine agonist).

Clinical Image

Image Description: ECG demonstrating sinus tachycardia, a common finding in neuroleptic malignant syndrome reflecting the autonomic instability characteristic of this condition.

Attribution: Image from Wikimedia Commons, Category: ECG graphs. Licensed under CC BY-SA 3.0. Source: https://commons.wikimedia.org/wiki/Category:ECG_graphs

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