Neuroleptic malignant syndrome develops in a very small number of people who are given certain types of drugs.
Symptoms include a dangerously high body temperature, muscle rigidity, and agitation.
Doctors base the diagnosis on the person's symptoms and on what they find during a physical examination.
Treatment involves stopping the drug, reducing body temperature, and providing support in an intensive care unit.
(See also Overview of Heat Disorders Overview of Heat Disorders Humans, who are warm-blooded animals, maintain their body temperature within 1 or 2 degrees of 98.6° F (37° C) as measured by mouth and 100.4° F (38° C) as measured rectally, despite large fluctuations... read more .)
Neuroleptic malignant syndrome develops in a small number of people who are treated with antipsychotic or antiemetic drugs (see table Drugs That Can Cause Neuroleptic Malignant Syndrome Drugs That Can Cause Neuroleptic Malignant Syndrome Neuroleptic malignant syndrome is confusion or unresponsiveness, muscle rigidity, high body temperature, and other symptoms that occur when certain antipsychotic (neuroleptic) drugs or anti-vomiting... read more ), usually within the first few weeks of treatment. The risk of developing the syndrome varies between 0.02% and 3% depending on many factors. The syndrome is most common among men who, because they are agitated, are given rapidly increased doses of antipsychotics or high doses initially. Doctors are not sure why the syndrome develops.
Symptoms usually develop over a few days and include
Damaged muscles release the protein myoglobin, which is excreted in the urine and turns the urine brown. This condition (myoglobinuria) can cause acute kidney injury Acute Kidney Injury Acute kidney injury is a rapid (days to weeks) decline in the kidneys’ ability to filter metabolic waste products from the blood. Causes include conditions that decrease blood flow to the kidneys... read more or even kidney failure Overview of Kidney Failure This chapter includes a new section on COVID-19 and acute kidney injury (AKI). Kidney failure is the inability of the kidneys to adequately filter metabolic waste products from the blood. Kidney... read more . About 10 to 20% of people die, even with rapid treatment.
Doctors suspect neuroleptic malignant syndrome when people taking a drug known to cause neuroleptic malignant syndrome develop characteristic symptoms and physical examination findings, particularly severe muscle rigidity. There are no tests that confirm the diagnosis. However, because other disorders (for example, meningitis Introduction to Meningitis Meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space). Meningitis can be... read more and sepsis Sepsis and Septic Shock Sepsis is a serious bodywide response to bacteremia or another infection plus malfunction or failure of an essential system in the body. Septic shock is life-threatening low blood pressure ... read more ) can cause similar symptoms, doctors often do tests for those disorders. Doctors also do blood and urine tests to look for muscle protein breakdown and kidney injury.
People with neuroleptic malignant syndrome are usually treated in an intensive care unit. The drug that caused neuroleptic malignant syndrome is stopped and fever is controlled, usually by wetting (misting) and blowing air over the skin or by using special cooling blankets. People who are very agitated are given sedatives by vein. Other treatments of possible but unproven benefit are often used because of the severity of this condition. These include dantrolene (a muscle relaxant, to reduce fever and muscle damage) and bromocriptine (to improve nerve function).