The patient was a 76-year-old woman who developed involuntary movements in both hands and gait disorder. Weakness in both lower limbs gradually worsened, and she was referred to our hospital. Neurological findings included spastic paraplegia, deep sensory disturbance, sensory ataxia, and bladder and bowel dysfunction. Approximately 4 months after the onset, she became unable to walk independently and had to use a walker. MRI showed a long spinal cord lesion extending from the cervical to thoracic spinal cord. Blood and spinal fluid samples tested positive for anti-human T-cell leukemia virus type 1 (HTLV-1) antibodies. Given these findings and subacute course, she was diagnosed with rapidly progressive HTLV-1 associated myelopathy (HAM). High levels of neopterin and CXCL10 in the cerebrospinal fluid suggested high disease activity；thus, she underwent steroid pulse therapy followed by treatment with maintenance oral prednisolone in our convalescent rehabilitation ward. After approximately 3 months of muscle strength training, mainly for the trunk muscle and the proximal muscle of the lower limbs, and balance exercise, she was able to walk independently and her activities of daily living (ADL) and instrumental ADL (IADL) improved；however, dysuria persisted. The use of clean intermittent self-catheterization instead of indwelling urethral catheter improved her quality of life (QOL). Although rapidly progressive HAM is generally associated with poor prognosis, steroid therapy combined with comprehensive rehabilitation treatment was effective in the present case.

The patient was a 76-year-old woman who developed involuntary movements in both hands and gait disorder. Weakness in both lower limbs gradually worsened, and she was referred to our hospital. Neurological findings included spastic paraplegia, deep sensory disturbance, sensory ataxia, and bladder and bowel dysfunction. Approximately 4 months after the onset, she became unable to walk independently and had to use a walker. MRI showed a long spinal cord lesion extending from the cervical to thoracic spinal cord. Blood and spinal fluid samples tested positive for anti-human T-cell leukemia virus type 1 (HTLV-1) antibodies. Given these findings and subacute course, she was diagnosed with rapidly progressive HTLV-1 associated myelopathy (HAM). High levels of neopterin and CXCL10 in the cerebrospinal fluid suggested high disease activity；thus, she underwent steroid pulse therapy followed by treatment with maintenance oral prednisolone in our convalescent rehabilitation ward. After approximately 3 months of muscle strength training, mainly for the trunk muscle and the proximal muscle of the lower limbs, and balance exercise, she was able to walk independently and her activities of daily living (ADL) and instrumental ADL (IADL) improved；however, dysuria persisted. The use of clean intermittent self-catheterization instead of indwelling urethral catheter improved her quality of life (QOL). Although rapidly progressive HAM is generally associated with poor prognosis, steroid therapy combined with comprehensive rehabilitation treatment was effective in the present case.