Progressive Multifocal Leukoencephalopathy

What is Progressive Multifocal Leukoencephalopathy?

Progressive multifocal leukoencephalopathy is a rare form of infection that affects the brain. It is caused by the JC virus and it usually results in death within just 9 months of infection.

What causes progressive multifocal leukoencephalopathy?

This is a rare and very serious brain infection caused by the JC virus. In most cases, this virus is acquired during childhood, but causes symptoms in very few adults. Normally, the virus lies dormant, but sometimes, triggers can cause it to start multiplying and this produces symptoms. Infection is most common in people who have a compromised immune system, including those with leukaemia, HIV, AIDS and lymphoma and those who take drugs to suppress the immune system (this may be the case following an organ transplant or when an individual has an autoimmune condition, for example).

What are the symptoms?

The JC virus rarely causes symptoms until it is activated. Once this happens, symptoms can come on gradually and tend to get worse as time goes by. The nature of symptoms depends on the area of the brain that is infected. In around two thirds of cases, cognitive function is affected and people experience symptoms similar to dementia. Mobility may also be affected and vision can be impaired. In rare cases, individuals might suffer from headaches and seizures.

What is the prognosis?

Most people die within 1-9 months of infection. However, there have been cases where people have survived longer, sometimes up to 2 years.  

How is progressive multifocal leukoencephalopathy diagnosed?

Doctors use a combination of assessing symptoms and MRI scanning to reach a diagnosis. A lumbar puncture is also often carried out to analyse the cerebral fluid. A technique known as PCR (polymerase chain reaction) is used to identify the presence of the JC virus.

Is there a treatment?

So far, no treatments have proven effective, however treating the underlying cause of weakened immunity can prolong life expectancy. For example, using antiretroviral therapy to treat HIV and stopping taking immunosuppressant medications. It is possible to develop IRIS (immune reconstitution inflammatory syndrome) if you are undergoing treatment or stop taking immunosuppressants. This occurs when the body’s immune system tries to fight the JC virus and can usually be treated with steroids.

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