Methotrexate-Induced Subacute Combined Degeneration in Acute Lymphoblastic Leukemia with CNS Relapse May Be Reversible

We describe a case of a female patient with acute lymphoblastic leukemia treated with high-dose systemic methotrexate and intrathecal methotrexate for leukemic relapse of the central nervous system. She developed complete bilateral lower-limb paralysis that was not attributable to any other cause. She was treated with folic acid, vitamin B12, methionine, S-adenosylmethionine, leucovorin, and dextromethorphan. After a 3-month period of paraplegia, she began to slowly recover motor function. She can now ambulate with assistance and continues to improve. There is a paucity of literature on methotrexate-induced subacute combined degeneration, which is typically described as irreversible. In addition to reporting our unique case, we review the published literature and call for more awareness and research in this area.