Late effects of unilateral brain lesions sustained before and after age one.

Forty-eight children with unilateral cerebral lesions, incurred before or after the first year of life, were given the Wechsler Intelligence Scale for Children, with an average delays of 4 and 8 1/2 yr for the late and early injuries, respectively. Thirty-one of their siblings were chosen as controls. Results are as follows: early and late right-hemisphere lesions significantly lower only Performance IQ. Early left lesions impair equally Verbal and Performance IQ, while late left-hemisphere lesions do not significantly affect Verbal or Performance IQ relative to controls.