NMS was first characterized during the 1960s, soon after the introduction of the first antipsychotic drugs.
Fortunately, NMS is less common than it used to be.
This article discusses the symptoms and causes of NMS, as well as how it is diagnosed and treated.
Morsa Images/DigialVision/Getty Images
Morsa Images/DigialVision/Getty Images
What Are the Symptoms of Neuroleptic Malignant Syndrome?
The symptoms of NMS may start out gradually and worsen over a few days.
Two of the classic symptoms of NMS are muscular rigidity and high fever.
Not everyone with NMS will have all of these symptoms.
NMS may be more difficult to diagnose in someone without these classic symptoms.
What Causes Neuroleptic Malignant Syndrome?
Dopamine System
The central nervous system contains many neurons that respond to the neurotransmitter dopamine.
Many different medical conditions are characterized by alterations in dopamine systems in the brain.
Conditions such asParkinsons diseasehave other problems with dopamine production and stimulation.
Researchers still arent sure why only a small percentage of people taking these drugs develop NMS.
Most commonly, NMS occurs after a person is given a drug that blocks dopamine receptors.
However, in NMS, something triggers a side effect from the drug.
NMS is more common with older typical antipsychotics like haloperidol.
Other types of drugs that affect dopamine receptors can also cause NMS.
For example, certain drugs to prevent vomiting (such asmetoclopramide) also block certain dopamine receptors.
Sometimes increasing these drugs can lead to NMS.
In other cases, NMS can occur after a drug is stopped or dramatically decreased.
Drugs such as levodopa can be given to helpincreasedopamineproduction.
For example, levodopa can be used to treat someone with Parkinsons disease.
If a person stops, steps down, or switches these types of medications, NMS might occur.
In both cases, a person is receiving less dopamine stimulation than before.
Exactly why this can trigger NMS is still unclear.
It probably involves a complex series of physiological events.
This is what leads to problems such as increased pulse and breathing rate.
Changes in dopamine may also lead to unexpected effects on muscle cells, triggering muscular rigidity.
How Is NMS Diagnosed?
The diagnosis of NMS is sometimes difficult, as it can resemble other conditions.
Other drug-induced syndromes, like serotonin syndrome, also must be eliminated as possibilities.
Serotonin syndrome can cause symptoms quite similar to NMS.
The clinical exam and medical history provide important starting points.
Several laboratory tests can aid with diagnosis, partly by eliminating other diagnostic possibilities.
These tests also may help in monitoring potential complications.
This has reduced long-term effects and death rates from the syndrome.
Affected individuals need close monitoring in an intensive care unit.
The initial step is stopping the dopamine-blocking drug that triggered the problem.
However, sometimes there are permanent problems related to NMS, such as kidney failure.
Genetic factors may play a role, but these are not yet known.
It is important to monitor people who have recently started dopamine-blocking drugs for early symptoms.
This is especially important for people who have started injectable, long-acting medications.
It is also important to monitor people with Parkinsons disease who are stopping medication or changing their treatment regimen.
This careful monitoring can lead to early diagnosis and treatment.
If a person experiences NMS, it is important not to restart a similar drug too soon.
Generally speaking, one needs to wait at least a couple of weeks before resuming treatment.
Then your healthcare provider can slowly reintroduce a drug with careful monitoring.
Dont stop taking medications without first consulting your treatment teamthat might lead to other major problems.
However, you may be able to use another medication with a lower risk of NMS.
For example, you might be able to switch from an older drug to a newer atypical antipsychotic drug.
Be sure to discuss any concerns with your healthcare team.
Summary
Neuroleptic malignant syndrome is a rare but serious syndrome resulting from medicationsparticularly certain psychiatric medications.
Two classic symptoms of NMS are muscular rigidity and high fever, though several other symptoms may also occur.
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