Progressive Multifocal Leukoencephalopathy (PML) Symptoms

Progressive Multifocal Leukoencephalopathy (PML) is a disease caused by a virus that destroys the myelin in the brain. Myelin, the substance that gives the brain's white matter its color, is a fatty material that covers and protects the nerve fibers. It helps speed the signals that the brain sends through the nerves to the rest of the body. Without this protection, the nerves are unable to send the signals, thus causing the symptoms of this often lethal disease.

The disease progresses slowly at first, then more rapidly, destroying the myelin over time, in different areas of the brain. Symptoms develop as the destruction grows and reflect which areas of the brain are being destroyed.

The symptoms of PML at first are common to those of other diseases, making it difficult to diagnose the illness at first. Early symptoms usually begin gradually and then increase more rapidly over time. In the beginning, they may resemble symptoms of multiple sclerosis (MS).

In fact, persons with MS who are in remission often believe their disease is relapsing when they actually have PML. In addition, MS patients take a drug for their condition, Tysabri (natalizumab), which weakens the immune system and makes them susceptible to the virus causing PML.

The symptoms of PML may include:

  • Difficulty walking
  • Clumsiness
  • Progressive weakness of the arms and legs
  • Other movement problems
  • Decline in mental abilities
  • Problems seeing
  • Difficulty speaking

Cause of PML

PML is caused by the JC virus (John Cunningham virus), which exists in most people in a latent state. Eighty-six percent of adults have antibodies to the virus, meaning they have been exposed to it, but it remains harmless. When the immune system becomes compromised, for example in AIDs patients, or in patients taking immunosuppressive drugs, the virus is activated. It then travels to the brain where it begins its destructive activity.

In February 2010, the U.S. Food and Drug Administration (FDA) issued a safety alert for patients and health care providers about finding an increased occurrence of PML among patients taking Tysabri. The drug was approved in November 2004 to treat relapsing forms of MS and also is approved for treating certain cases of Crohn's disease. The safety alert warned that the risk of developing PML increased with the number of infusions of the drug. The FDA called for revisions to the drug label and the patient Medication Guide based on the findings.

Legal Help for PML Patients

If you or a loved one is diagnosed with this serious disease after taking Tysabri®, Rituxan™, Raptiva®, or another type of medication, you might be eligible for compensation. Our PML lawyers can help you get the compensation you need and deserve. Call today and schedule a free evaluation of your case.

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