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:
- Mental status changes including alteration of the level of the
consciousness. Often these symptoms may be underestimated if the
patient has a concomitant psychiatric condition. (5)
- Muscular rigidity often characterized by ”lead-pipe rigidity” and
cogwheel phenomenon. (6)
- Hyperthermia with not unusual spikes over 38°C. However, lower
temperatures are more often associated with second-generation
antipsychotics (7)
- Autonomic instability usually presenting with tachycardia, labile
blood pressure and tachypnoea. (6)
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)