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Progressive Multifocal Leukoencephalopathy

  • Cynthia M. Johnson, MA
Publication Type:


Progressive Multifocal Leukoencephalopathy



Progressive Multifocal Leukoencephalopathy (PML) is a rare disease of the white matter of the brain.

The Neuron.

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PML is caused by an infection by the John Cunningham 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 cells called oligodendrocytes. These cells make the material that insulates nerve cells, or neurons.

Risk Factors

PML is most common in people who have problems with their immune system. These problems may be from:

  • HIV/AIDS (most common)
  • Organ transplant
  • Leukemia and lymphoma
  • Cancer
  • Long term use of steroid medicines or other medicine that suppresses the immune system, such as some medicines that treat multiple sclerosis (MS)
  • Rare immune system problems that have been passed from parent to child


PML gets worse over time. A person may have:

  • Lack of strength in the arms and legs
  • Problems moving
  • Changes in behavior and thinking
  • Memory problems
  • Problems seeing
  • Speech problems or a loss of language
  • Sensory loss
  • Signs of seizures, such as jerking arm and leg motions


The doctor will ask about 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, the doctor may need:

  • Lumbar puncture to look for the virus in the fluid that surrounds the brain
  • Brain biopsy to look for the virus in brain tissue


The goal of treatment is to make the immune system stronger to slow harm to the body. There is no cure for PML. The doctor may advise:

  • Antiretroviral medicine for people who have HIV
  • Stopping any medicine that weakens the immune system
  • A plasma exchange to quickly remove any medicine that weakens the immune system from the blood


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.





  • Grebenciucova, E. and 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/health-information/disorders/progressive-multifocal-leukoencephalopathy.
  • Progressive multifocal leukoencephalopathy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/progressive-multifocal-leukoencephalopathy-pml.
  • Progressive multifocal leukoencephalopathy (PML). AETC National Coordinating Resource Center website. Available at: https://aidsetc.org/resource/progressive-multifocal-leukoencephalopathy-pml.
  • Williamson, E.M.L. and Berger, J.R. Diagnosis and treatment of progressive multifocal leukoencephalopathy associated with multiple sclerosis therapies. Neurotherapeutics, 2017; 14 (4): 961-973.


  • Rimas Lukas, MD
Last Updated:

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.