Diagnostic Criteria for NMS:
(1) treatment with neuroleptic agent prior to onset
(1a) within 7 days for oral agents
(1b) within 2-4 weeks for depot forms
(2) hyperthermia >= 38°C (may be delayed in onset)
(3) muscle rigidity
(4) 5 or more of the following:
(4a) change in mental status
(4b) tachycardia
(4c) hypertension or hypotension
(4d) tachypnea or hypoxia
(4e) diaphoresis (excessive sweating) or sialorrhea (excessive flow of saliva)
(4f) tremor
(4g) incontinence
(4h) creatine phosphokinase (CK) elevation or myoglobinuria
(4i) leukocytosis
(4j) metabolic acidosis
(5) exclusion of other drug-induced, systemic or neuropsychiatric illnesses
Differential diagnosis:
(1) serotonin syndrome – This does not show muscle rigidity.
(2) anticholinergic syndrome
Limitations:
• This definition requires use of a neuroleptic agent. Other authors include non-neuroleptic agents, but this introduces the problems of differentiation from the other conditions with overlapping symptomatology.
