Neuropsychological sequelae of postradiation somnolence syndrome.

Postirradiation somnolence syndrome in children with acute lymphocytic leukemia treated with cranial irradiation has been identified as a possible precursor of later cognitive dysfunction. To test this, the neuropsychological evaluation of 48 children who developed somnolence syndrome was compared with that of 31 children who did not have the syndrome at approximately 1 1/2 and 3 3/4 years after treatment. No differences in performance between the two groups were found on many measures of neuropsychological functioning with the exception of fine motor speed. Children without somnolence syndrome scored somewhat less than normal on measures of academic achievement. No other differences from normal performance were noted in either group. The results of the study indicated that if children with somnolence are at greater risk for the development of cognitive dysfunction than those not manifesting the syndrome, such risks occur at a time farther from treatment than 3 to 4 years.