Abstract
Mefloquine, an antimalarial medication with efficacy against JC virus, was used to treat progressive multifocal leukoencephalopathy. A 54-year-old woman with sarcoidosis presented with a progressive cerebellar syndrome. MRI showed lesions affecting the right cerebellum that progressed over time to the brainstem. JC virus was found in the cerebrospinal fluid (CSF), and brain biopsy confirmed the diagnosis of progressive multifocal leukoencephalopathy. Mefloquine 1000 mg/week was initiated 6 months after symptom onset. Clinical progression stopped immediately, and JC virus became undetectable in the CSF. No clinical or imaging evidence of disease progression has occurred over 20 months of follow-up. This is the first report of successful treatment of progressive multifocal leukoencephalopathy with mefloquine.