Progressive Multifocal Leukoencephalopathy
(PML)
Pronounced: LOO-koh-en-sef-ah-LOP-ah-thee
Definition
PML is a rare, slowly progressive disease of the nervous system. It is caused by a viral infection of oligodendrocytes. These are cells that produce myelin.
The Neuron
Causes
PML is caused by a papovavirus, known as JC virus. Most people get this infection in childhood, and it produces no illness. It reactivates later in life in people who have a suppressed immune system (eg, HIV/AIDS ).
Risk Factors
The most common risk factor is having HIV/AIDS. PML has rarely been associated with:
- Leukemia and lymphoma
- Tuberculosis
- Sarcoidosis
- Prolonged immunosuppression (organ transplant or cancer patients)
- Chronic steroid therapy
- Rare inherited immunodeficiencies
- Natalizumab (medication used to treat multiple sclerosis )—the risk may only occur when also taking other immunosuppressants
Symptoms
If you experience any of these symptoms do not assume it is due to PML. These symptoms may be caused by other conditions. Symptoms progress over weeks and include:
Diagnosis
Your doctor will ask about your symptoms and medical history. She will also do a physical exam. Tests may include:
- MRI scan —a test that uses magnetic waves to make pictures of structures inside the brain (key in the diagnosis)
- Spinal tap —removal of a small amount of cerebrospinal fluid to check for evidence of the JC virus in the brain
- Blood and urine tests
- Brain biopsy
RESOURCES:
AIDS.org
http://www.aids.org/
National Organization for Rare Disorders
http://www.rarediseases.org/
CANADIAN RESOURCES:
Canadian AIDS Society
http://www.cdnaids.ca/
Canadian Organization for Rare Disorders
http://www.cord.ca/
References:
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 . Accessed September 30, 2005.
Progressive multifocal leukoencephalopathy. EBSCO DynaMed website. Available from DynaMed: http://www.ebscohost.com/dynamed . Updated January 10, 2008. Accessed February 23, 2008.
Progressive multifocal leukoencephalopathy. Medline Plus Medical Encyclopedia website. Available at: http://www.nlm.nih.gov/medlineplus/ency/article/000674.htm . Accessed September 30, 2005.
Last reviewed January 2009 by Rimas Lukas, MD
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