To determine the relationship between malformations of cortical development and intellectual functioning (IQ), 54 children and adolescents with intractable epilepsy who later underwent cortical resection were studied at the Miami Children’s Hospital, FL. Cortical lesions were classified as circumscribed or diffuse. Circumscribed lesions had less adverse effect on nonverbal IQ than diffuse cortical dysplasias. The same was true for verbal measures, but only with right-sided lesions. Left-sided lesions were associated with poor performance on verbal IQ tests, when compared to right-sided lesions. Younger age at onset and diffuse lesions were risk factors for greater impairment of cognitive functioning. 
COMMENT. In children with intractable epilepsy, cortical diffuse dysplasias acquired in utero and early left hemisphere lesions affect cognitive functioning more adversely than circumscribed lesions or right hemisphere developmental lesions.