Early cognitive and communication development in children with focal brain lesions.

Early cognitive and language development of children with congenital focal brain lesions, documented by magnetic resonance imaging, was studied in 18 cases, 9 with left-hemisphere damage and 9 with right-hemisphere damage, at about 2 (Time 1) and 4 years of age (Time 2). All of the children showed normal cognitive development, but their global Griffiths Developmental Scales scores were lower at Time 2, and developmental profiles across individual subscales revealed side-specific effects, resembling the adult left/right cerebral hemisphere lesion model. Expressive lexicon and grammar were delayed, more often in left-hemisphere-damaged than in right-hemisphere-damaged children, at Time 1 and Time 2. Functional findings were not related to the size and location of the brain lesion, whereas the presence of epilepsy was a highly significant predictor of cognitive and language outcome, irrespective of the side of the lesion. The stable disadvantage in the verbal domain shown by left-hemisphere-damaged children within the age range of this study might suggest that the left hemisphere has some initial bias for language learning. The effects of right-hemisphere damage were more variable and emerged at a later stage of language development.