710 Medication-Induced Movement Disorders
Diagnostic Features
Patients have generally been exposed to a dopamine antagonist within 72 hours prior to
symptom development. Hyperthermia ( 100.4 F or 38.0C on at least two occasions,
measured orally), associated with profuse dia phoresis, is a distinguishing feature of neu-
roleptic malignant syndrome, sett ing it apart from other neurol ogical side effects of anti-
psychotic medications. Extreme elevations in temperature, reflecting a breakdown in
central thermoregulation, are more likely to support the diagnosis of neuroleptic malig-
nant syndrome. Generalized rigidity, described as “lead pipe” in its most severe form and
usually unresponsive to antiparkinsonian agen ts, is a cardinal feature of the disorder and
may be associated with other neurological symptoms (e.g., tremor, sialorrhea, akinesia,
dystonia, trismus, myoclonus,  dysarthria, dysphagia, rhab domyolysis). Creatine kinase
elevation of at least four times the upper limit of normal is commonly seen. Changes in
mental status, characterized by  delirium or altered consciousness ranging from stupor to
coma, are often an early sign. Affected indi viduals may appear alert but dazed and unre-
sponsive, consistent with catatonic stupor. Autonomic activation and instability—mani-
fested by tachycardia (rate 25% above baseline), diaphoresis, blood pressure elevation
(systolic or diastolic 25% above baseline) or fluctuation ( 20 mmHg diastolic change or