Reversible dementia temporally associated with intraventricular therapy with methotrexate in a child with acute myelogenous leukemia.

During maintenance therapy with intraventricular methotrexate, progressive dementia developed in a child with meningeal leukemia. Cerebrospinal fluid levels of MTX were in the nontoxic range and neurologic evaluation failed to demonstrate anatomic obstruction, infection, or folate depletion. The patient's symptoms gradually resolved when the methotrexate was discontinued, suggesting that methotrexate neurotoxicity may occur in the absence of an elevated CSF concentration of MTX.