[Refractory multiple myeloma with impaired consciousness accompanied by hyperammonemia and leukoencephalopathy-like findings].

A 81-year-old female was diagnosed with symptomatic multiple myeloma (MM; IgG κ type, D&S: IIB, ISS: 2) in August 2017. Although treatment with lenalidomide and dexamethasone was started, she developed deep venous thrombosis in the lower extremities as a complication; therefore, the treatment was changed to DBd. In February 2018, she required hospitalization due to general weakness and altered consciousness.