The effects of cranial irradiation on neuropsychological test performance, 9 months after diagnosis of acute lymphoblastic leukemia (ALL), were evaluated in 74 children aged 3 to 6 years included in the Children’s Cancer Group cooperative treatment trials. Children who received cranial irradiation (18 Gy divided in 10 fractions) plus intrathecal methotrexate had significantly lower scores on the McCarthy Motor Scale and the Token Test of receptive language and auditory comprehension, when compared to children receiving intrathecal methotrexate alone. Performance of tests of general cognition, visual motor integration, and receptive language requiring verbal recognition and visual recognition (Peabody Picture Vocabulary Test-R) showed no differences among the treatment groups. 
COMMENT. In the past nine months issues of PNB have included two previous reports of the adverse effects of cranial irradiation in children treated for ALL. In a study from the Institute of Child Health, University of London, children who received a second course of cranial radiotherapy for relapsing LL suffered from neurologic deficits, growth impairment, ventricular enlargement on MRI, and impairments of tests of verbal comprehension, attention, and memory. Girls were affected more than boys. (Ped Neur Briefs June 1994;8:47). Hypoplasia of the cerebellar vermis and cognitive deficits involving visual-spatial-motor coordination and memory were reported at 9 year follow-up in 13 children who received 24 Gy cranial radiation and intrathecal methotrexate at the University of New Mexico and centers in Canada. (Ped Neur Briefs Nov 1994;8:82). The late morbidity associated with cranial radiotherapy has been recognized for some time. The Children’s Cancer Group study demonstrates that cognitive deficits may become evident as early as 9 months after treatment, even with more moderate levels of irradiation. Whole-brain radiotherapy for brain tumors may also result in significant IQ deficits in children treated before age 7. (Progress in Pediatric Neurology II, 1994, pl99).