[Chronic progressive radiation myelopathy after bone marrow transplantation]

Two patients after bone marrow transplantation (BMT) developed chronic progressive radiation myelopathy (CPRM). The factors contributing to development of CPRM at the low dose, which radiation doses given for enlarged regional lymph nodes prior to BMT ordinarily would be too low to induce CPRM, were discussed, and clinicoradiologic correlations in CPRM from onset through the stabilized state examined. The clinicoradiologic findings of two patients, who are a 26-year-old man with malignant lymphoma (autologous BMT) performed radiotherapy totaling 20 Gy for enlarged regional lymph nodes before BMT, and a 40-year old woman with chronic myeloid leukemia (allogenic BMT) done 18.9 Gy, were examined. The involved spinal cord segments were irradiated for lymph node enlargement prior to BMT, and all the clinicoradiologic findings were consistent with CPRM. We considered possible synergistic toxicity with high-dose busulfan accompanying BMT. Unlike the second case, the first patient had continued severe progression of CPRM, possibly because a higher dose of additional radiotherapy (30 Gy) was given for presumed spinal cord tumor involvement in that case than in the other (< 20 Gy). These cases demonstrate that BMT protocols carry a risk of potentiating the spinal cord toxicity of low-dose radiotherapy.