ABSTRACT
Methotrexate is the most widely used intrathecal antineoplastic agent and is potentially neurotoxic. Accidental intrathecal overdose of methotrexate can produce severe and life-threatening toxicities. A 17-year-old girl with acute lymphocytic leukemia, in complete remission, inadvertently received a 10-fold overdose of intrathecal methotrexate instead of intended dose (100mg vs 10mg). Exchange of lumbar cerebrospinal fluid with normal saline via intrathecal indwelling catheter was started 2 hours later. Leucovorin and dexamethasone were given intravenously. After exchange of cerebrospinal fluid, the total amount of methotrexate removed was about 37mg. Cerebrospinal fluid and plasma methotrexate levels at 18 hours were about 3- to 5- fold higher than those previously reported in patients following standard dose of intrathecal methotrexate who did not develop neurotoxicity. But no methotrexate induced neurologic sequelae were observed in this patient. CSF exchange is a simple and effective method for the treatment of acute intrathecal methotrexate overdose.