The disorder, which is caused by a common human polyomavirus, JC virus, is characterized by demyelination or destruction of the myelin sheath that covers nerve cells. The myelin sheath is the fatty covering which acts as an insulator on nerve fibers in the brain. In rare cases, seizures may occur. There is no cure for PML, nor is there currently an effective treatment for the disorder.
Treatment is symptomatic and supportive.
The course of PML is relentlessly progressive. Hall, CD, et al. Failure of Cytosine Arabinoside Therapy of HIV-1 Associated Progressive Multifocal Leukoencephalopathy. Koralnik, I, et al. The Pathogenesis and Clinical Course of Progressive Multifocal Leukoencephalopathy.