Introduction
Neuroleptic Malignant Syndrome (NMS) is a rare but potentially fatal adverse side effect more often associated with the use of first-generation antipsychotic medications. (1) However, NMS is also associated with the use of second-generation antipsychotic and antiemetic drugs. (2-3)
Cases of NMS have been reported in patients treated for Parkinsonism after dopamine agonist therapy withdrawal or dose reduction (4)
Typical clinical manifestations include:
Relevant laboratory findings include raised serum creatine kinase (CK)The more the muscular rigidity is marked, the more creatine kinase is elevated.CK levels higher than 1000 international units/L are more specific for NMS and they are linked with a more severe presentation and prognosis. (6)
Leucocytosis and electrolytes abnormalities are common but nonspecific (6-8)
The incidence of NMS is relatively infrequent, ranging between 0.2% and 3%(4-6).NMS is a life-threatening condition and its mortality is estimated between 5 and 20% according to older literature. Mortality is increased in patients with rhabdomyolysis, myoglobinuria and renal failure. (9) A case report of a patient taking Olanzapine 10mg developed NMS and subsequent rhabdomy­olysis-induced acute renal failure that was successfully treated with haemodialysis. (10)
Initial management includes stopping any potential possible causative medicationssuch as antipsychotics, or restart anti-Parkinsonian agents.
Benzodiazepines (especially Lorazepam and Diazepam) are used for the treatment ofmental state disturbances such as agitation. Lorazepam can be given also as first line to reduce rigidity. Dantrolene can be used for the same purpose as well. (11)
Fundamental is the supportive treatment with oxygen and measures to reduce temperature and IV fluids. IV sodium bicarbonate is given to prevent renal failure secondary to rhabdomyolysis. (12-13-14)