Ketamine as an Adjunct for Treatment of Methotrexate-induced Neurotoxicity

Methotrexate (MTX) is used in the treatment of several childhood cancers and is a main component of the treatment regimen for osteosarcoma. MTX has been linked with side effects of varying severity; headaches, nausea, emesis, lethargy, blurred vision, aphasia, hemiparesis, paresis, convulsions, leukoencephalopathy, and arachnoiditis are symptoms of MTX toxicity. MTX-induced neurotoxicity can occur in up to 15% of patients receiving high-dose MTX. The effects may be transient but can have life-threatening implications, sometimes requiring intubation for respiratory support and airway protection. Elevated homocysteine levels in the cerebrospinal fluid are documented in cases of MTX-induced neurotoxicity; dextromethorphan is used as an initial treatment for MTX-induced neurotoxicity as it works as a noncompetitive antagonist for the N-methyl D-aspartate receptors and suppresses homocysteine activity. In severe cases requiring intubation, medications for sedation are utilized. Ketamine is also an N-methyl D-aspartate receptor antagonist, and as such, may be considered as an optimal treatment choice when sedation is required. We describe the use of ketamine in a pediatric patient with MTX-induced neurotoxicity. The use of ketamine in the treatment of MTX-induced neurotoxicity has not been described in the literature.