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Neuroleptic Malignant Syndrome: Differential Diagnoses & Workup

Author: Theodore I Benzer, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Director of Clinical Operations, Director of Toxicology, Chair of Quality and Safety, Department of Emergency Medicine, Massachusetts General Hospital
Contributor Information and Disclosures

Updated: Aug 18, 2009

Differential Diagnoses

Encephalitis
Toxicity, Cocaine
Herpes Simplex
Toxicity, Cyclic Antidepressants
Herpes Simplex Encephalitis
Toxicity, Lithium
Polymyositis
Toxicity, MDMA
Rabies
Toxicity, Medication-Induced Dystonic Reactions
Renal Failure, Acute
Toxicity, Methamphetamine
Rhabdomyolysis
Toxicity, Monoamine Oxidase Inhibitor
Spider Envenomations, Widow
Toxicity, Neuroleptic Agents
Toxicity, Amphetamine
Toxicity, Selective Serotonin Reuptake Inhibitor
Toxicity, Anticholinergic
Withdrawal Syndromes
Toxicity, Antihistamine

Other Problems to Be Considered

Parkinsonism
Pheochromocytoma
Serotonin syndrome
Strychnine toxicity
Dystonic reactions
Lethal catatonia

Workup

Laboratory Studies

  • Complete blood count (CBC)
  • Blood cultures
  • Liver function tests (LFTs)
  • Blood urea nitrogen (BUN) and creatinine levels
  • Calcium and phosphate levels
  • Creatine kinase level
  • Urine myoglobin level
  • Arterial blood gas (ABG) level
  • Prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR)
  • Serum and urine toxicologic screening (eg, salicylates, cocaine, amphetamines)

Imaging Studies

  • Perform chest radiography, if aspiration pneumonia is a concern.
  • Perform a head CT to evaluate for a structural lesion or before a lumbar puncture (LP). No universal agreement exists on the absolute need for a CT scan before the LP in patients without clinical evidence of a structural lesion; the decision is left to the individual practitioner.

Procedures

  • The LP is indicated to rule out meningitis in patients exhibiting fever and altered mental status.

More on Neuroleptic Malignant Syndrome

Overview: Neuroleptic Malignant Syndrome
Differential Diagnoses & Workup: Neuroleptic Malignant Syndrome
Treatment & Medication: Neuroleptic Malignant Syndrome
Follow-up: Neuroleptic Malignant Syndrome
References
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References

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Further Reading

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Keywords

neuroleptic malignant syndrome, neuroleptic medication, NMS, idiosyncratic reaction, muscular rigidity, autonomic dysfunction, haloperidol, fluphenazine, antipsychotic agents, prochlorperazine, promethazine, clozapine, risperidone, metoclopramide, amoxapine, lithium, dopamine D2-receptor antagonist, withdrawal of anti-Parkinson medication, respiratory failure, cardiovascular collapse, myoglobinuric renal failure, arrhythmias, diffuse intravascular coagulation, DIC, rhabdomyolysis, pneumonia, renal failure, seizures, hyperthermia, profuse diaphoresis, sialorrhea, metabolic acidosis, dopamine receptor blockade, impaired temperature regulation

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Contributor Information and Disclosures

Author

Theodore I Benzer, MD, PhD, Assistant Professor in Medicine, Harvard Medical School; Director of Clinical Operations, Director of Toxicology, Chair of Quality and Safety, Department of Emergency Medicine, Massachusetts General Hospital
Theodore I Benzer, MD, PhD is a member of the following medical societies: Alpha Omega Alpha and American College of Emergency Physicians
Disclosure: Nothing to disclose.

Medical Editor

Mark S Slabinski, MD, FACEP, FAAEM, Vice President, EMP Medical Group
Mark S Slabinski, MD, FACEP, FAAEM is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Emergency Physicians, American Medical Association, and Ohio State Medical Association
Disclosure: Nothing to disclose.

Pharmacy Editor

John T VanDeVoort, PharmD, Regional Director of Pharmacy, Sacred Heart & St. Joseph's Hospitals
John T VanDeVoort, PharmD is a member of the following medical societies: American Society of Health-System Pharmacists
Disclosure: Nothing to disclose.

Managing Editor

Michael J Burns, MD, Instructor, Department of Emergency Medicine, Harvard University Medical School, Beth Israel Deaconess Medical Center
Michael J Burns, MD is a member of the following medical societies: American Academy of Clinical Toxicology, American College of Emergency Physicians, American College of Medical Toxicology, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Asim Tarabar, MD, Assistant Professor, Department of Surgery, Section of Emergency Medicine, Yale University School of Medicine; Consulting Staff, Department of Emergency Medicine, Yale-New Haven Hospital
Disclosure: Nothing to disclose.

 
 
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