Progressive multifocal leukoencephalopathy presenting with an isolated focal movement disorder

Progressive multifocal leukoencephalopathy (PML) is a rare but fatal papova virus infection of the central nervous system predominantly affecting immun ocompromised patients. Although the basal ganglia circuitry may be involved in the pathology of PML, movement disorders are exceedingly rare as presen ting symptoms and have not been described as isolated features in such pati ents. We report a previously healthy, immunocompetent 24-year-old woman wit h histologically proven PML who presented with a focal movement disorder of the left ann as an isolated symptom for many months before diagnosis.