Early lexical development in children with focal brain injury.

Early lexical development in 27 children with focal brain injury was studied cross-sectionally and longitudinally. Data were obtained from children between 12 and 35 months of age who acquired their lesion prenatally or within the first 6 months of life. Results for the group as a whole provide clear evidence for delays in lexical comprehension and production, and for a larger number of comprehension/production dissociations than would be expected by chance. In addition, a significant number of children were observed having unusual difficulty mastering predication and/or using an atypically high proportion of closed class words (suggesting reliance on holistic/formulaic speech). Analyses by lesion type revealed no effect of lesion size. Analyses according to side of lesion revealed that children with right-hemisphere damage produced a higher proportion of closed class words, suggesting heavy reliance on well-practiced but under-analyzed speech formulae. Children with left-hemisphere damage were slightly better in comprehension than children with right-hemisphere damage. In addition, left posterior lesions were associated with greater delays in expressive language, and delays were more protracted in children with left posterior damage. No differential effects of left posterior damage were found for lexical comprehension.