Clinical vigilance for progressive multifocal leukoencephalopathy in the context of natalizumab use

Abstract
Natalizumab therapy for patients with multiple sclerosis (MS) has been associated with both improved clinical outcomes and an increased incidence of progressive multifocal leukoencephalopathy (PML). We provide details of the etiology and recent history of PML as associated with immunosuppressive disease states, including MS. Furthermore, it offers clinical guidance on differentiating PML from a MS relapse and a review of the current treatment options for patients suspected of having developed the complication.