[Natalizumab can induce progressive multifocal leucoencephalopathy].

A 41-year-old woman with relapsing-remitting multiple sclerosis came to the outpatient-clinic, prior to a scheduled infusion with natalizumab. She had been treated with natalizumab for four years. Prior to treatment she did not wish to have her John Cunningham virus status tested. At the consultation she appeared disoriented and answered questions inadequately. An MRI was consistent with progressive multifocal leucoencephalopathy, and treatment with plasmapheresis was startet immediatly. The patient deceased four months later.