Progressive multifocal leukoencephalopathy

Alternate names

Leukoencephalopathy, progressive multifocal; PML

Definition

Progressive multifocal leukoencephalopathy (PML) is a neurological disorder that damages the myelin that covers and protects nerves in the white matter of the brain.

Cause

The John Cunningham virus, or JC virus (JCV) causes PML. JC virus is also known as human polyomavirus 2. By age 10, most people have been infected with this virus though it hardly ever causes symptoms.

Risk factors

But people with a weakened immune system are at risk of developing PML. Causes of a weakened immune system include:

• HIV/AIDS (less common cause of PML now because of better management of HIV/AIDS).
• Certain medicines that suppress the immune system called monoclonal antibodies. Such medicines may be used to prevent organ transplant rejection or to treat multiple sclerosis, rheumatoid arthritis and other autoimmune disorders, and related conditions.
• Cancers, such as leukemia and Hodgkin lymphoma.

Signs and symptoms

Symptoms may include any of the following:

• Loss of coordination, clumsiness
• Loss of language ability (aphasia)
• Memory loss
• Vision problems
• Weakness of the legs and arms that gets worse
• Personality changes

Diagnosis

Tests may include:

• Brain biopsy (in rare cases)
• Cerebrospinal fluid test for the JCV
• CT scan of the brain
• Electroencephalogram (EEG)
• MRI of the brain

Treatment

• Currently, the best available therapy is reversal of the immune-deficient state, since there are no effective drugs that block virus infection without toxicity.
• Reversal may be achieved by using plasma exchange to accelerate the removal of the therapeutic agents that put patients at risk for PML.
• In the case of HIV-associated PML, immediately beginning anti-retroviral therapy will benefit most individuals.
• Several new drugs that laboratory tests found effective against infection are being used in PML patients with special permission of the U.S. Food and Drug Administration.
• Hexadecyloxypropyl-Cidofovir (CMX001) is currently being studied as a treatment option for JVC because of its ability to suppress JVC by inhibiting viral DNA replication.

Prognosis

• In general, PML has a mortality rate of 30-50 percent in the first few months following diagnosis but depends on the severity of the underlying disease and treatment received.
• Those who survive PML can be left with severe neurological disabilities.

NIH genetic and rare disease info

• NIH info on Progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy is a rare disease.

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