Neuroleptic Malignant Syndrome (NMS)
Neuroleptic Malignant Syndrome
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 who get NMS recover fully with treatment.
What causes NMS? — NMS is usually related to medicines called "neuroleptics." These medicines are 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 usually start within 2 weeks of starting the medicine. But in some cases, they happen after just 1 dose, or after taking the medicine for years.
Sometimes medicines used to treat or prevent vomiting can also cause NMS. But this is less common. The table has a list of the different 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 the 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, breathing faster than normal, 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 above symptoms, call for help. If symptoms are severe or the person seems very ill, call for an ambulance (in the US and Canada, dial 9-1-1).
How can doctors tell if a person has NMS? — They can usually figure this out based on the medicines a person takes and the symptoms they are having. There is no 1 test that can show for sure whether or not a person has NMS. But blood tests can show whether it is likely. That's because people with NMS usually have a high level of something called "creatine kinase" in their blood.
The doctor will order other tests, too. This can help them figure out if something else might be causing the person's symptoms. Tests might include:
Imaging tests – Imaging tests create pictures of the inside of the body. They might include a CT scan or MRI of the brain.
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 (also called "EEG") – This test measures electrical activity in the brain.
How is NMS treated? — The main treatment is to stop the medicine that has caused NMS.
People with NMS will need to stay in the hospital for monitoring and treatment. This might involve:
Monitoring of breathing, heart rate, and blood pressure, and treating any problems in these areas
Treatments to lower body temperature, such as cooling blankets, ice, or medicines
IV fluids (through a thin needle that goes into a vein)
Medicines to prevent blood clots
Medicines to help keep the person calm
Some doctors try to treat NMS directly with medicines. This might involve medicines that relax the muscles (called "muscle relaxants") or medicines that are also used to treat Parkinson disease. This sometimes seems to help, although there is not a lot of good evidence that any of these medicines work.
If other 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 has had NMS before, there are things doctors can do to lower the 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 in order to avoid getting dehydrated.
All topics are updated as new evidence becomes available and our peer review process is complete.
This topic retrieved from UpToDate on: Mar 30, 2020.
Topic 121211 Version 1.0
Release: 28.2.2 - C28.105
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