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 antiretroviral 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.
There are no current guidelines to prevent exposure to the JC virus. If you have a suppressed immune system, follow your treatment plan to minimize your risk.
- Reviewer: Rimas Lukas, MD
- Review Date: 05/2016 -
- Update Date: 06/02/2014 -