Disparity of Verbal and Performance IQ Following Early Bilateral Brain Damage

Abstract

To examine the effects of early bilateral brain damage on Full Scale IQ (FSIQ), Verbal IQ (VIQ) and Performance IQ (PIQ). Early unilateral brain damage typically results in relatively spared intellectual function, with IQ in the normal range and no significant differences between VIQ and PIQ, regardless of the side of the lesion. However, little is known about intellectual function in children after bilateral damage. FSIQ, VIQ, and PIQ scores of 10 children, ages 6-12 years, with early-onset bilateral focal lesions (BFL), were compared with those of age- and sex-matched controls. FSIQ was in the average range for BFL and control children. A bimodal distribution of VIQ was identified, resulting in 2 distinct groups, one performing above the average range and the other below. The unimpaired group displayed a significant discrepancy between VIQ and PIQ, with VIQ in the superior range and PIQ in the low average range. The impaired group did not demonstrate disparate VIQ and PIQ: both were in the borderline range. The 2 groups were differentiated by greater degree of cortical brain damage in the impaired than in the unimpaired group. The striking difference between the outcome of the unimpaired and impaired groups may reflect different processes of reorganization that are associated with the extent of cortical involvement.