Cognitive functioning in long-term survivors of childhood leukemia: a prospective analysis

Treatment-related cognitive impairments have been reported for survivors of childhood leukemia following prophylactic central nervous system (CNS) treatment with 2400 cGy craniospinal irradiation and intrathecal chemotherapy. The present study was designed to prospectively evaluate cognitive functioning of 24 children prior to CNS prophylaxis of 1800 cGy of craniospinal irradiation and intrathecal drugs, and at intervals of 1 and 4-5 years. At diagnosis, prior to CNS treatment, all 24 subjects performed in the average range of intelligence, as measured by the Wechsler Intelligence Scales. Subjects continued to perform in the average range with no significant declines at the 1-year follow-up. Significant declines in cognitive functioning, however, were found at the 4- to 5-year follow-up period, with five subjects (21%) performing in the low average or borderline levels of intelligence. Of the 19 subjects performing in the average range, five showed significant discrepancies between Verbal and Performance IQ scores. Nine subjects exhibited poor performance on a subtest cluster assessing perceptual and attentional processes. With regard to school experiences, 50% of the subjects had received some type of special education services. The findings indicate the need for annual evaluations of cognitive functioning in long-term survivors of childhood leukemia who received 1800 cGy craniospinal irradiation, to identify potential cognitive late effects of treatment requiring appropriate special education services.