Progressive Multifocal Leukoencephalopathy

What is Progressive Multifocal Leukoencephalopathy?

Progressive multifocal leukoencephalopathy (PML) is an infrequent disorder of the nervous system that primarily affects individuals with suppressed immune systems (including, allograft recipients such as kidney transplant patients; patients with cancers such as leukemia or lymphoma; and nearly 10% of patients with acquired immune deficiency syndrome — AIDS. The disorder, which is caused by a common human polyomavirus, JC virus, is characterised 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. Symptoms of PML include mental deterioration, vision loss, speech disturbances, ataxia (inability to coordinate movements), paralysis, and, ultimately, coma reflecting the multifocal distribution of brain lesions. In rare cases, seizures may occur.

Is there any treatment?

There is no cure for PML, nor is there currently an effective treatment for the disorder. Treatment is symptomatic and supportive.

What is the prognosis?

The course of PML is relentlessly progressive. Death usually occurs between 1 and 4 months after onset, but there have been a number of reported cases with survival for months to years.