Progressive multifocal leukoencephalopathy (PML) is a disease of the white matter of the brain, caused by a virus infection that targets cells that make myelin--the material that insulates nerve cells (neurons).
No treatment for PML has proved to be effective. However, treating the disorder that has weakened the immune system helps people survive longer. For example, if the cause of PML is AIDS, highly active antiretroviral therapy is employed.
One third up to one half of people with PML die in the first few months (within 9 months to 2 years) following diagnosis, depending on the severity of their underlying disease. Survivors can be left with variable degrees of neurological disabilities.
If people taking immunosuppressants stop taking the drugs, it may cause progressive multifocal leukoencephalopathy to subside. Those who survive PML can be left with severe neurological disabilities.
Immune reconstitution inflammatory syndrome (IRIS) may affect people treated with antiretroviral therapy or who stop taking immunosuppressants. In this disorder, the recovering immune system launches an intense attack against the JC virus, thus worsening symptoms. Corticosteroids may help relieve symptoms.
In the pre-HAART era, the outlook in patients with PML in HIV was depressing, and in most cases, death occurred in approximately 95% of patients within 4-6 months after diagnosis. Approximately 8% of patients experienced unprompted recovery.
With the widespread acceptance of highly active antiretroviral therapy (HAART), the incidence of PML diminished considerably. In addition, several case series have shown sustained survival for patients receiving HAART.
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