Leukoencephalopathy induced by low-dose methotrexate in a patient with rheumatoid arthritis.

We report a patient with rheumatoid arthritis (RA) who developed leukoencephalopathy while being treated with low-dose methotrexate (MTX). She suddenly developed loss of recent memory and left homonymous hemianopsia ascribable to the bilateral but right-predominant occipitotemporal lesions. Intravenous administration of dexamethasone and cessation of MTX quickly relieved her clinical symptoms. Low-dose MTX-induced leukoencephalopathy is a rare complication in RA, but is important with regard to the possibility of serious neurological sequellae.