Post-irradiation somnolence syndrome in an adult patient following allogeneic bone marrow transplantation

Neurologic disturbances are common following the intensive chemotherapy and radiotherapy of bone marrow transplantation (BMT) conditioning regimens. The somnolence syndrome, which occurs in most children treated for leukemia with prophylactic cranial irradiation, has previously not been reported following BMT. This syndrome consists of transient lethargy, irritability, headaches, low grade fevers, gastrointestinal disturbances and depression. We report the case of a 38-year-old female with acute non-lymphocytic leukemia who developed symptoms typical of the somnolence syndrome 8 weeks following 1320 cGy total body irradiation and cyclophosphamide conditioning. Encephalographic findings were consistent with the syndrome, and no additional infectious or metabolic disorders could be identified. As predicted by the pediatric experience, the symptoms were transient, resolving following steroid and anti-depressant therapy. Among patients undergoing radiation based conditioning regimens, especially those not receiving concurrent steroid therapy, the appearance of post-transplantation somnolence may be an expression of this syndrome.