Neuroleptic malignant syndrome (NMS)
NMS is a life-threatening psychiatric emergency associated with the use of antipsychotic (neuroleptic) agents. This is a , idiosyncratic reaction to the exposure of antipsychotics. It is characterized by a distinctive clinical syndrome of mental status change, rigidity, fever, and autonomic instability.
Neuroleptic malignant syndrome , which occurs in approximately 0.2% of patients receiving neuroleptics
Symptoms of neuroleptic malignant syndrome usually include very high fever (102 to 104 degrees F), irregular pulse, accelerated heartbeat (tachycardia), increased rate of respiration (tachypnea), muscle rigidity, altered mental status, autonomic nervous system dysfunction resulting in high or low blood pressure, profuse perspiration, and excessive sweating.
Other symptoms may include liver or kidney failure, abnormally high potassium levels (hyperkalemia), major destruction of skeletal muscle tissue (rhabdo-myolysis) or blood clots in veins and arteries.
The cause of NMS is unknown. Current theories are limited in their ability to explain all clinical manifestations and in supporting data. The dopamine receptor blockade is central to most theories of its pathogenesis. Central dopamine receptor blockade in the hypothalamus may cause hyperthermia and other signs of dysautonomia. Interference with nigrostriatal dopamine pathways may lead to parkinsonian-type symptoms such as rigidity and tremor.. Other neurotransmitter systems (gamma aminobutyric acid, epinephrine, serotonin, and acetylcholine) also appear to be involved, either directly or indirectly.
A genetic basis for the disorder is suspected but not proven. It does appear to be clear that a defect in the receptors to dopamine (dopamine D2 receptor antagonism) is an important contributor to the cause of neuroleptic malignant syndrome.
Diagnosis:
The diagnosis of neuroleptic malignant syndrome is based on the presence of characteristics that include treatment with neuroleptic drugs within the past 1-4 weeks. high body temperature (greater than 38 degrees centigrade); muscle rigidity; and at least five of the following:
Change in mental status
Rapid heart beat (tachycardia)
Low or high blood pressure (hypo- or hypertension)
Excessive sweating (diaphoresis)
Excessive saliva production (sialorrhea)
Tremor
Incontinence
Increased creatine phosphokinase, or increased urinary myoglobin
Increased number of white blood cells (leukocytosis)
Increased concentrations of metabolic acids in blood and urine
Exclusion of other drug-induced psychiatric or systemic illness.
Treatment
Treatment of neuroleptic malignant syndrome consists of withdrawal of
neuroleptic medications under a doctor's supervision, immediate measures to restore appropriate water and nutrient levels, and steps to lower the individual's body temperature. Medications prescribed as treatment may include skeletal muscle relaxants, such as dantrolene; stimulators of dopamine production and activity, such as bromocriptine; and/or continuous perfusion of central nervous system depressants, such as diazepam.
Complications that may result from neuroleptic malignant syndrome, such as kidney (renal) insufficiency, deficiency of oxygen reaching the tissues (hypoxia), and/or decreased alkalinity of the blood and tissues (acidosis) can be extremely serious and must be treated immediately. Once patients have recovered from neuroleptic malignant syndrome, about 87% will be able to tolerate an antipsychotic at some point in the future. Physicians usually switch to a different antipsychotic class and to an atypical antipsychotic. Such patients must be carefully monitored since recurrences of neuroleptic malignant syndrome are not infrequent.
Electroconvulsive treatments have been prescribed for patients with neuroleptic malignant syndrome with varied results.