How to Say It: LOO-koh-en-sef-ah-LOP-ah-thee
Progressive Multifocal Leukoencephalopathy (PML) is a rare disease of the white matter of the brain.
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PML is caused by an infection by a specific virus. Many people get this virus as a child, but do not get sick until later. It stays in the body and does not cause problems in most people.
The virus can start to cause problems in people with a weak immune system. It attacks the cells that make the material that insulates nerve cells (neurons).
PML is most common in people who have problems with their immune system. These problems may be from:
PML gets worse over time. Problems may be:
You will be asked about your symptoms and health history. A physical exam will be done.
An MRI scan will be done to look for damage to the brain.
To confirm PML, your doctor may need:
There is no cure. The goal of treatment is to strengthen the immune system to slow harm to the body. Choices are:
The virus that causes PML cannot be prevented. PML may be prevented in people with HIV by taking steps to prevent the immune system from weakening.
AIDS Information, Education, Action
NORD—National Organization for Rare Disorders
Canadian AIDS Society
CORD—Canadian Organization for Rare Disorders
Grebenciucova E, Pruitt A. Infections in patients receiving multiple sclerosis disease-modifying therapies. Curr Neurol Neurosci Rep. 2017;17(11):88.
Progressive multifocal leukoencephalopathy information page. National Institute of Neurological Disorders and Stroke website. Available at https://www.ninds.nih.gov/Disorders/All-Disorders/Progressive-Multifocal-Leukoencephalopathy-Information-Page. Accessed October 2, 2020.
Progressive multifocal leukoencephalopathy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/progressive-multifocal-leukoencephalopathy-pml. Accessed October 2, 2020.
Progressive multifocal leukoencephalopathy (PML). AETC National Resource Center website. Available at:
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Accessed October 2, 2020.
Williamson EML, Berger JR. Diagnosis and Treatment of Progressive Multifocal Leukoencephalopathy Associated with Multiple Sclerosis Therapies. Neurotherapeutics. 2017 Oct;14(4):961-973.
Last reviewed September 2020 by
EBSCO Medical Review Board
Rimas Lukas, MD
Last Updated: 5/25/2021