Beginning in January 1998, the study was extended for an additional four years through December 2001 to compare the effects of the two intraoperative methods with respect to developmental and neurologic status at eight years of age. Developmental status was assessed by the Wechsler Individual Achievement Test (primary outcome) and by the presence of learning disabilities and performance in specific neuropsychologic domains (secondary outcomes). Neurologic status was determined by neurologic exam (primary outcome) and by specific types of dysfunction such as motor problems. The study also compared the academic and intellectual performance of the cohort at age eight years to population norms and used the data to identify correlates of the children's eight year outcomes, as well as their development between ages one and eight.