PML is a rare progressive disease of the nervous system. PML is caused by a viral infection of the cells that produce myelin.
PML is caused by a specific papovavirus, known as John Cunningham (JC) virus. Many people get this infection in childhood. It produces no illness and generally does not infect the nervous system. It reactivates later in life in people who have suppressed immune systems. The virus damages oligodendrocytes, the cells in the central nervous system (CNS) which produce myelin, the material that wraps around nerves. Less myelin around the nerves impairs nerve function.
PML is most common in people with suppressed immune systems. Suppressed immune systems may be the result of:
Symptoms progress over weeks and may include:
Your doctor will ask about your symptoms and medical history. A physical exam will be done. Tests may include:
Treatment focuses on strategies to improve the immune system. If you have HIV, your doctor will most likely prescribe medications to treat this condition. If PML has resulted from the drug natalizumab, your doctor will have you stop taking this drug and may recommend a plasma exchange to remove the drug from your blood system.
AIDS Information, Education, Action, Awareness
NORD—National Organization for Rare Disorders
Canadian AIDS Society
CORD—Canadian Organization for Rare Disorders
NINDS progressive multifocal leukoencephalopathy information page. National Institute of Neurological Disorders and Stroke website. Available at http://www.ninds.nih.gov/disorders/pml/pml.htm. Updated February 14, 2014. Accessed June 2, 2014.
Progressive multifocal leukoencephalopathy. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116949/Progressive-multifocal-leukoencephalopathy-PML. Updated January 8, 2016. Accessed September 26, 2016.
Progressive multifocal leukoencephalopathy (PML). AETC National Resource Center website. Available at: http://aidsetc.org/resource/progressive-multifocal-leukoencephalopathy-pml. Updated May 1, 2013. Accessed June 2, 2014.
Warnke C, Menge T, Hartung HP, et al. Natalizumab and progressive multifocal leukoencephalopathy: what are the causal factors and can it be avoided? Arch Neurol. 2010;67(8):923-930.
Last reviewed January 2018 by Rimas Lukas, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.