Cranial irradiation and platelet monoamine oxidase in ALL.

Prophylactic cranial irradiation in acute lymphoblastic leukemia (ALL) has been held responsible for long-term neuropsychological sequelae. This study evaluates the activity of monoamine oxidase (MAO) in children with ALL in first complete remission both before and after cranial irradiation, given to prevent central nervous system involvement. There was a significant decrease (p less than 0.025) in platelet MAO activity shortly after cranial irradiation. MAO activity values were in the normal range in patients investigated 3 months or more after the radiation treatment was completed. The pathogenesis and clinical relevance of this decrease are discussed.