What Is Progressive Multifocal Leukoencephalopathy?
Progressive multifocal leukoencephalopathy (PML) is a rare and serious infection that attacks part of your brain. You can get it when your body can't fight off disease the way it should.
It damages your brain's white matter, cells that make a substance called myelin. Myelin protects your nerves, and losing it can make it harder for you to move, think, and feel sensations. PML is often life-threatening, but prompt treatment can often slow down its progression.
PML is caused by a virus called the JC virus (JCV). Up to 85% of all adults carry this virus, and it usually doesn't cause any health problems. But it can if you have a seriously weakened immune system, which means your body's natural defenses against illness aren't working well.
Progressive Multifocal Leukoencephalopathy Symptoms
What are the first signs of PML?
The first symptoms of PML differ from person to person, depending on which nerves are damaged first. But they often include:
- Clumsiness or loss of coordination
- Trouble walking
- Facial drooping
- Personality changes
- Trouble speaking
- Weak muscles
What are the later signs of PML?
Progressive multifocal leukoencephalopathy usually gets worse over time. As it progresses, you may have:
- Dementia
- Loss of speech
- Vision loss
Sometimes, PML can also cause headaches or seizures.
Progressive Multifocal Leukoencephalopathy Risk Factors
About 1 in every 200,000 people will get PML. That works out to a total of about 4,000 people a year in the U.S. and Europe combined.
It happens most often to people who have HIV or AIDS, which attacks the immune system. But people who have some types of cancer, such as leukemia and lymphoma, also are at a higher risk. So are those who take drugs that keep their bodies from rejecting transplanted organs.
People who take medications that suppress or modify the immune system are also at risk. That includes some drugs for multiple sclerosis, which attacks the central nervous system, and other immune system problems, such as Crohn's disease, rheumatoid arthritis, and lupus.
A study presented at a meeting of the American Neurology Association showed that people with certain gene variations are at a higher risk of getting PML when they take one of these drugs. Some experts recommend taking a genetic test to see if you have these variants before starting the medications.
Progressive Multifocal Leukoencephalopathy Diagnosis
If your doctor thinks you might have PML, they'll likely scan your brain with an MRI machine. It uses powerful magnets and radio waves to make a detailed picture of your brain. They'll look for lesions — spots of damaged tissue — that show the disease is there.
They could also do other imaging tests such as a CT scan or electroencephalogram (EEG).
If these tests don't give a clear picture, they might do a brain biopsy. They'll take a small sample of tissue from your brain to look at under a microscope for signs of the disease.
Your doctor may also order a lumbar puncture (spinal tap) to take a sample of the fluid around your brain and spinal cord for testing.
Progressive Multifocal Leukoencephalopathy Treatment
The best way to treat PML is to fight whatever has made your immune system weak. You might take drugs that attack the virus that causes AIDS (HIV) or avoid drugs that affect your immune system. You might also need to avoid treatments such as chemotherapy, which can increase your risk of infections.
If your immune system is weak due to immunosuppressing drugs, your doctor might do a plasma exchange. This treatment removes some of the drugs from your bloodstream. This helps boost your immune system so it can fight off the JC virus.
Researchers are trying to find other drugs to fight the JC virus, but none have been approved for widespread use.
White matter killed by the virus doesn't grow back, so your symptoms may be permanent. Many people who have had PML live with the effects of nerve damage. These can be similar to the issues caused by a stroke and may include paralysis and memory loss.
Takeaways
Progressive multifocal leukoencephalopathy is a rare and serious brain infection that affects people who have very weak immune systems. It can be fatal or cause permanent brain and nerve damage. But prompt treatment can often slow down its progression.
Progressive Multifocal Leukoencephalopathy FAQs
What is the life expectancy of someone with progressive multifocal leukoencephalopathy?
That depends on how serious your PML is, what caused it, and how well treatment works for you. Some 30% to 50% of those who get PML will die in the first few months after their diagnosis.
Does PML ever go away?
Some people do survive progressive multifocal leukoencephalopathy. But any nerve damage it has caused doesn't go away.
What drugs cause multifocal leukoencephalopathy?
PML has been linked to nearly 100 drugs that suppress your immune system (called immunosuppressants) or change it (immunomodulators). They include medications used to treat cancer, Crohn's disease, lupus, multiple sclerosis, and rheumatoid arthritis. They include:
- Natalizumab (Tysabri), used to treat MS
- Rituximab, also used for MS
- Brentuximab vedotin (Adcetris), which treats Hodgkin's lymphoma
What are the side effects of multifocal leukoencephalopathy?
Nerve damage from PML may leave you with serious disabilities such as problems with your vision, movement, and thinking.
