A "cortico-basal degeneration"-like syndrome as first sign of progressive multifocal leukoencephalopathy.

We report an unusual case of probable progressive multifocal leukoencephalopathy (PML), who initially presented with a right-sided movement disorder, including upper limb dystonia, tremor, and dyspraxia, reminiscent of corticobasal degeneration. In the further course, the patient developed disorientation, confusion, and bradyphrenia. The appearance of white matter MRI lesions as well as a positive PCR test result for JC-virus in the cerebrospinal fluid finally led to the correct diagnosis.