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Progressive Multifocal Leukoencephalopathy

Progressive Multifocal Leukoencephalopathy (PML) is an irregular disorder of the nervous system that mainly affects individuals with suppressed immune systems (including, allograft recipients such as kidney transplant patients; patients with cancers such as leukemia or lymphoma; and approximately 10% of patients with acquired immune deficiency syndrome (AIDS).

The disorder, which is caused by a frequent 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.

Some prescription medications that treat Multiple Sclerosis have been found to cause Progressive Multifocal Leukoencephalopathy (PML). There have been reports of people suffering PML (Progressive Multifocal Leukoencephalopathy), while taking Avonex and Tysabri.

In many circumstances both Avonex and Tysabri are taken together by those who suffer from multiple sclerosis. Tysabri was withdrawn from the market after 2 recent reports of serious side effects among patients who used it along with Avonex. In one instance, the person died, while in another, the person developed a suspected case of progressive multifocal leukoencephalopathy, a rare and frequently fatal disease of the central nervous system.

PML often results in irreversible neurological deterioration and death. Both patients had taken Avonex for more than two years in combination with Tysabri, the two drugs manufacturers said. Other symptoms of PML consist of mental deterioration, vision loss, paralysis, speech disturbances, ataxia (inability to coordinate movements), and comas. In rare cases, seizures can happen. The worst side effect includes death, which occurs for the most part between 1 and 4 months after onset. But, in some circumstances, survival lasts months to years. 

Progressive in PML means that it continues to get worse and often leads to serious brain damage. Multifocal means that the JC virus causes disease in several different parts of the brain. Leukoencephalopathy indicates that the disease affects the white matter of the brain. More specifically, the JC virus infects cells in the brain called oligodentrocytes. These cells are responsible for producing myelin, a fatty substance that helps protect nerves in the brain. When too much myelin is lost and not replaced by oligodentrocytes, the nerves become damaged and over time stop working properly.

If you or a loved one has taken prescription medications that treat Multiple Sclerosis and were diagnosed with Progressive Multifocal Leukoencephalopathy (PML), please fill out the form at the right for a free case evaluation by a qualified defective drug attorney.