Progressive Multifocal Leukoencephalopathy in Multiple Sclerosis

Progressive multifocal leukoencephalopathy (PML) is a rare and debilitating disease caused by the JC virus and results in demyelination of oligodendrocytes and glial cell lysis. The virus is able to cross the blood brain barrier, leading to plaque development on the brain and neurological problems. (Gorelik et al., 2011). PML develops in individuals who have an immune disorder and who have been treated with immunomodulatory medications, including patients with Multiple Sclerosis (MS). There is no cure for PML and 30-50% of patients who develop the disease die within the first few months of diagnosis. The JC virus is thought to affect 66-92% of the general population and is acquired in childhood (White & Khalili, 2011). Despite the prevalence of JC antibodies after exposure, the actual occurrence of PML is low leading to the conclusion that the virus is re-activated, after a period of latency, in immunosuppressed individuals (White & Khalili, 2011). The pathophysiology of the disease is significant in that many patients diagnosed with MS, who are undergoing immunosuppression therapy, may also have JC virus antibodies which increases their risk of reactivating the infection and results in PML. Therefore, screening and close observation is warranted in the patient with MS