An Adult Case of Methotrexate-related Stroke-like Encephalopathy Responsive to Dextrometorphan
Michele Persico1, Christy Soares1, Tyler Kristoff2, Nikolaos Papadantonakis2, Sara Radmard1
1Department of Neurology, 2Department of Hematology and Medical Oncology, Emory University
Objective:
- To report that MTX-induced stroke-like encephalopathy can respond to the N-methyl-D-aspartate receptor agonist dextromethorphan at a dose range of 1.4-2.3 mg/kg/day for 4-14 doses in adults.
Background:
Methotrexate (MTX)-induced stroke-like encephalopathy is a rare neurological complication after administration of the chemotherapeutic agent MTX via intravenous or intrathecal route and can be responsive to high-dose leucovorin or off-label dextromethorphan. Limited data are available on the dosage and efficacy of dextromethorphan administration in MTX-induced stroke-like encephalopathy in adults compared to children.
Results:
We present a case of a 39-year-old Hispanic woman with B-cell acute lymphoblastic leukemia who presented with one day of sudden-onset left leg and arm weakness and generalized fatigue occurring 18 and 10 days after receiving 15 mg of intratechal MTX. Neurological exam on presentation was significant for 4+/5 in the left upper and 4/5 in the left lower extremities. MRI of the brain revealed focal restricted diffusion of the right centrum semiovale extending to the vertex without corresponding T2/fluid-attenuated inversion recovery (FLAIR) sequence signal abnormality. She was diagnosed with MTX-induced stroke-like encephalopathy. Leucovorin 8 mg administered every twelve hours was started without symptom improvement. On hospital day two, her symptoms worsened, and she was started on dextromethorphan 1.9 mg/kg/day divided into three doses per day for five days. After five days, she was able to ambulate again and the neurological exam revealed 5/5 strength in all muscle groups of the left upper and lower extremity, except for 4/5 in the left digit flexors. She was full strength at her two-month post-discharge outpatient neurology visit.
Conclusions:
MTX-induced stroke-like encephalopathy can respond to dextromethorphan treatment in adults with complete resolution of symptoms. While a dose range of 1.4-2.3 mg/kg/day for 4-14 doses has been reported in one case series, further reports and larger studies are needed to refine the dextromethorphan administration parameters.
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