Patient education: Neuroleptic malignant syndrome (The Basics)

What is neuroleptic malignant syndrome? — 

Neuroleptic malignant syndrome, or "NMS," is a rare but serious problem that can happen to people who take certain medicines. It is a medical emergency that can lead to death if not treated quickly. But most people recover fully with treatment.

What causes NMS? — 

NMS is usually related to medicines called "neuroleptics," also called "antipsychotics." They are used to treat different disorders, such as schizophrenia, that can cause people to have trouble thinking normally.

In people who get NMS, symptoms often start within 2 weeks of starting the medicine. But in some cases, they happen after just 1 dose, or after taking the medicine for months or even years.

Sometimes, medicines used to treat or prevent vomiting can also cause NMS. But this is less common. The table lists some of the medicines that can cause NMS (table 1).

NMS can also happen in people with Parkinson disease. When this happens, it is typically related to stopping certain medicines too quickly, or lowering the dose.

What are the symptoms of NMS? — 

The main symptoms are:

●Changes in thinking and behavior – The person might act confused or agitated. They might also stop moving or speaking.

●Very stiff or rigid muscles – Some people also have a tremor, which is when parts of the body shake. There can be other problems with muscles, too, like trouble talking or swallowing.

●Fever – This means a temperature above 100.4°F (38°C). In some cases, the fever gets very high, with a temperature of 104°F (40°C) or even higher.

●Changes in some of the body's basic functions – These can include a fast or abnormal heart rate, high blood pressure, fast breathing, and sweating a lot. Normally, the body controls these things automatically. In NMS, things are not controlled as well as they should be.

People with NMS are very ill, and are at risk for other serious problems, too. These can include heart problems, kidney failure, dangerous blood clots, infection, and other issues.

Should I call the doctor or nurse? — 

Yes. If you know someone who takes any of the medicines that can cause NMS, and they develop the symptoms listed above, call for help. If symptoms are severe or the person seems very ill, call for an ambulance (in the US and Canada, call 9-1-1).

How can doctors tell if a person has NMS? — 

There is no test that shows for sure whether a person has NMS. But blood tests can help because most people with NMS have a high level of a substance called "creatine kinase" in their blood.

Doctors make a diagnosis of NMS based on this blood test, the person's symptoms, and knowing they were taking a medicine that can cause NMS. They will also do tests to make sure something else is not causing the person's symptoms. Tests might include:

●Imaging tests, like a CT scan or MRI of the brain – These create pictures of the inside of the body.

●A lumbar puncture (also called "spinal tap") – This is a procedure used to get a sample of fluid from around the spinal cord. The fluid can then be tested for infection or other problems.

●An electroencephalogram, or "EEG" – This measures electrical activity in the brain.

How is NMS treated? — 

The main treatment is to stop the medicine that caused NMS.

People with NMS need to stay in the hospital for monitoring and treatment. This might involve:

●Monitoring their breathing, heart rate, and blood pressure, and treating any problems

●Treatments to lower body temperature, such as cooling blankets, ice, or medicines

●Fluids given through an "IV," which is a thin tube that goes into a vein

●Medicines to prevent blood clots

●Medicines to help keep the person calm

Some doctors also use medicines to treat the symptoms of NMS if they are severe. This might involve medicines to relax muscles (called "muscle relaxants") or medicines that are also used to treat Parkinson disease.

In rare cases, if these treatments do not help, doctors might try something called electroconvulsive therapy, or "ECT." This is a treatment sometimes used for depression. It involves passing a small electric current through the brain in a safe way.

After treatment, most people get better within about 2 weeks, and do not have long-term problems. In severe cases, or if the person does not get treatment quickly enough, NMS can lead to death.

Can NMS be prevented? — 

The best way to avoid NMS is to avoid the medicines that can cause it. But in many cases, a person really needs these medicines to treat their condition. If a person had NMS before, there are things doctors can do to lower their risk of getting it again. They might wait a few weeks before restarting the medicine, switch to a different medicine, or lower the dose. After the person starts taking the medicine again, it's important to watch them closely for symptoms of NMS, so they can get treatment right away if needed. It might also help for the person to drink plenty of fluids to stay hydrated.

More on this topic

Patient education: Delirium (confusion) (The Basics)
Patient education: Schizophrenia (The Basics)
Patient education: Medicines for Parkinson disease (The Basics)

Patient education: Delirium (Beyond the Basics)
Patient education: Parkinson disease treatment options — medications (Beyond the Basics)