eMedicine Specialties > Pediatrics: Cardiac Disease and Critical Care Medicine > Critical Care

Neuroleptic Malignant Syndrome: Differential Diagnoses & Workup

Author: Mary C Mancini, MD, PhD, Professor, Department of Surgery, Louisiana State University Health Sciences Center
Coauthor(s): Girish G Deshpande, MD, MBBS, FAAP, Assistant Professor, Department of Pediatrics, Division of Critical Care Medicine, Children's Hospital of Illinois at OSF St Francis Medical Center
Contributor Information and Disclosures

Updated: Dec 9, 2008

Differential Diagnoses

Bacteremia
Substance Abuse: Cocaine
Head Trauma
Systemic Lupus Erythematosus
Hyperthyroidism
Tetanus
Meningitis, Aseptic
Thyroid Storm
Meningitis, Bacterial
Toxicity, Monoamine Oxidase Inhibitor
Multiple Endocrine Neoplasia
Toxicity, Selective Serotonin Reuptake Inhibitor
Pheochromocytoma
Schizophrenia and Other Psychoses

Other Problems to Be Considered

Neuroleptic malignant syndrome (NMS) is a diagnosis of exclusion; the following disorders create similar symptomatology:

Primary CNS disorders

Meningoencephalitis
Stroke
Trauma
Tumors
Major psychosis (eg, lethal catatonia)

Systemic disorders

Infections (eg, tetanus)
Metabolic conditions
Endocrinopathies (eg, thyrotoxicosis, pheochromocytoma)
Autoimmune diseases (eg, systemic lupus erythematosus)
Sepsis

Miscellaneous

Heat stroke
Strychnine poisoning
Central anticholinergic syndrome
Sympathomimetic intoxication
Serotonin syndrome
Monoamine oxidase inhibitor (MAOI) overdose
Lithium overdose
Alcohol or sedative-hypnotic withdrawal
Malignant hyperthermia

Workup

Laboratory Studies

No laboratory test result is diagnostic for neuroleptic malignant syndrome (NMS).

  • Evidence of increased muscular activity
    • Elevated creatinine kinase (50-100% of cases)
    • Metabolic acidosis
    • Increased transaminases
    • Myoglobinuria
  • CBC count showing leukocytosis (70-98% of cases)
  • Electrolyte levels that indicate hyperkalemia, metabolic acidosis
  • Renal function tests indicating prerenal (dehydration) and renal (myoglobinuria) failure
  • Coagulation studies, such as platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT), if thromboembolic phenomenon or diffuse intravascular coagulation (DIC) is suspected
  • Cultures from various sites to look for infections
  • Cerebrospinal fluid (CSF) analysis to rule out meningitic or encephalitic process

Imaging Studies

  • Imaging studies (eg, CT scanning, MRI) of the brain may be performed to rule out other conditions such as intracranial hemorrhage (ICH) or trauma. They per se do not yield any diagnostic information for neuroleptic malignant syndrome.
  • Chest radiography is indicated for suspected aspiration pneumonia.

Histologic Findings

  • Neuroleptic malignant syndrome has an associated increase of MM isoenzyme of creatine kinase.
  • Muscle biopsy reveals morphological and histoenzymological abnormalities in muscle fibers. These findings are nonspecific and are not diagnostic of neuroleptic malignant syndrome.

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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  3. Bismuth C, de Rohan-Chabot P, Goulon M, Raphael JC. Dantrolene--a new therapeutic approach to the neuroleptic malignant syndrome. Acta Neurol Scand Suppl. 1984;100:193-8. [Medline].

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  6. Ellenhorn MJ, Schonwald S, Ordog G. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins; 1997:663-4, 1187-1190.

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Further Reading

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Keywords

neuroleptic malignant syndrome, NMS, neuroleptics, antidopaminergic activity, serotonin, schizophrenia, respiratory failure, cardiovascular collapse, renal failure, arrhythmias, thromboembolism, hypoxia, ischemic encephalopathy, urinary incontinence, diaphoresis, sialorrhea, hypertension, respiratory distress, dehydration, hypotension, butyrophenones, haloperidol, phenothiazines, thioxanthenes, long-acting neuroleptics, benzamines, tricyclic antidepressants, monoamine oxidase inhibitors, MAOIs, anticonvulsants, lithium, domatine antagonists

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Contributor Information and Disclosures

Author

Mary C Mancini, MD, PhD, Professor, Department of Surgery, Louisiana State University Health Sciences Center
Mary C Mancini, MD, PhD is a member of the following medical societies: American Heart Association, American Medical Association, American Thoracic Society, Association for Academic Surgery, Association for Surgical Education, International College of Surgeons, International Society for Heart and Lung Transplantation, New York Academy of Sciences, Phi Beta Kappa, and Southern Thoracic Surgical Association
Disclosure: Nothing to disclose.

Coauthor(s)

Girish G Deshpande, MD, MBBS, FAAP, Assistant Professor, Department of Pediatrics, Division of Critical Care Medicine, Children's Hospital of Illinois at OSF St Francis Medical Center
Girish G Deshpande, MD, MBBS, FAAP is a member of the following medical societies: American Academy of Pediatrics
Disclosure: Nothing to disclose.

Medical Editor

G Patricia Cantwell, MD, Associate Clinical Professor, Department of Pediatrics, University of Miami; Director of Pediatric Critical Care Medicine, Miller School of Medicine, Jackson Children's Hospital
G Patricia Cantwell, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Emergency Physicians, American Heart Association, American Trauma Society, National Association of EMS Physicians, Society of Critical Care Medicine, and Wilderness Medical Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from broker recommendation; Avanir Pharma Stock Investment from broker recommendation

Managing Editor

Barry J Evans, MD, Assistant Professor of Pediatrics, Temple University Medical School; Director of Pediatric Critical Care and Pulmonology, Associate Chair for Pediatric Education, Temple University Children's Medical Center
Barry J Evans, MD is a member of the following medical societies: American Academy of Pediatrics, American College of Chest Physicians, American Thoracic Society, and Society of Critical Care Medicine
Disclosure: Nothing to disclose.

CME Editor

Mary E Cataletto, MD, Associate Director, Division of Pediatric Pulmonology, Winthrop University Hospital; Professor of Clinical Pediatrics, State University of New York at Stony Brook; Director of Children's Sleep Services, Winthrop University Hospital
Mary E Cataletto, MD is a member of the following medical societies: American Academy of Pediatrics and American College of Chest Physicians
Disclosure: Shering Plough Pharmaceuticals Honoraria Consulting

Chief Editor

Timothy E Corden, MD, Associate Professor of Pediatrics, Co-Director, Policy Core, Injury Research Center, Medical College of Wisconsin; Associate Director, PICU, Children's Hospital of Wisconsin
Timothy E Corden, MD is a member of the following medical societies: American Academy of Pediatrics, Phi Beta Kappa, Society of Critical Care Medicine, and Wisconsin Medical Society
Disclosure: Nothing to disclose.

 
 
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