Neuroleptic Malignant Syndrome: Diagnostic Criteria

This post is dedicated to the discussion of diagnostic criteria for neuroleptic malignant syndrome. Here is the summary of an international consensus study of Neuroleptic Malignant Syndrome diagnostic criteria using the Delphi method:

An international multispecialty panel of clinical experts reached a consensus regarding diagnostic criteria for NMS using the Delphi technique; however, until these consensus criteria are validated by future studies, they should be considered only as an aid to clinical diagnosis and not as the sole basis for excluding a diagnosis of NMS.

(1) Exposure to dopamine antagonist, or dopamine agonist withdrawal, within past 72 hours (Priority Score: 20)

(2) Hyperthermia (>100.4°F or >38.0°C on at least 2 occasions, measured orally) (Priority Score: 18)

(3) Rigidity (Priority Score: 17)

(4) Mental status alteration (reduced or fluctuating level of consciousness) (Priority Score: 13)

(5) Creatine kinase elevation (at least 4 times the upper limit of normal) (Priority Score: 10)

(6) Sympathetic nervous system lability, defined as at least 2 of the following: (Priority Score: 10)

  • Blood pressure elevation (systolic or diastolic ≥25% above baseline)
  • Blood pressure fluctuation (≥20 mm Hg diastolic change or ≥25 mm Hg systolic change within 24 hours)
  • Diaphoresis
  • Urinary incontinence

(7) Hypermetabolism (Priority Score: 5), defined as

  • Heart-rate increase (≥25% above baseline) AND
  • Respiratory-rate increase (≥50% above baseline)

(8) Negative work-up for infectious, toxic, metabolic, or neurologic causes (Priority Score: 7)


  • Gurrera RJ, Caroff SN, Cohen A, Carroll BT, DeRoos F, Francis A, Frucht S, Gupta S, Levenson JL, Mahmood A, Mann SC, Policastro MA, Rosebush PI, Rosenberg H, Sachdev PS, Trollor JN, Velamoor VR, Watson CB, Wilkinson JR. An international consensus study of neuroleptic malignant syndrome diagnostic criteria using the Delphi method. J Clin Psychiatry. 2011 Sep;72(9):1222-8. doi: 10.4088/JCP.10m06438. Epub 2011 Jun 28. (PubMed PMID: 21733489).

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