Somnolence syndrome in a child following 1200-cGy total body irradiation in an unrelated bone marrow transplantation.

Neurological complications may occur following intensive chemotherapy and hematopoietic cell transplantation. Postirradiation somnolence syndrome has been observed in children with acute lymphoblastic leukemia who received central nervous system preventive therapy with 1800-2400 cGy cranial irradiation. The authors report a 16-year-old boy with chronic myelogenous leukemia in chronic phase, who developed symptoms compatible with the somnolence syndrome (SS) 6 weeks following HLA-matched unrelated bone marrow transplantation (BMT). The preparative regimen consisted of 1200 cGy total body irradiation (TBI), cytosine arabinoside and cyclophosphamide. The patient developed lethargy and low-grade fever, with intermittent rhythmical delta activity in electroencephalograph. He recovered spontaneously without specific therapy 3 weeks after developing symptoms. This is the first report describing that as low as 1200 cGy TBI can induce SS in a child. After allogeneic BMT, some patients develop neurological symptoms. The authors suggest that somnolence syndrome should be included in differential diagnosis in these patients.