[Neuropsychological development in children with focal brain injury]

The study of children with focal brain injury has important implications from a clinical and theoretical perspective. Clinical data on children with congenital or early acquired lesions indicates that the cognitive sequelae are different from those resulting from similar damage sustained in adulthood. These differences depend in part on the differential effect that damage has on ongoing developmental process and in part on the different recovery capacity of the Central Nervous System of the child. From a theoretical perspective, focal lesion data is important for analyzing the issues of early neuropsychological functioning (especially in terms of early hemispheric specialization) and of plasticity and recovery of function of the CNS. This review analyzes the possible causes of this heterogeneity, that seems in part dependent on the interindividual variability of early neuropsychological organization and in part related to methodological factors such subject inclusion criteria and nature of neuropsychological measures. The review also discusses the role during development of the principal inter and intrahemispheric recovery mechanisms (special attention is given to intrahemispheric mechanisms which have been considered in the past as less determinant with respect to interhemispheric mechanisms). Furthermore, the role of lesion side as a prognostic parameter is discussed, specifically in terms of the evidence of a differential recovery capacity of left hemisphere with respect to the right. Various hypotheses have been put forward as possible interpretations of these data (maturational gradient, different neuropsychological organization of the two hemispheres), yet evidence is still controversial. If one considers the prognostic parameter--age of lesion onset--recent evidence does not confirm the hypothesis that the earlier the lesion, the greatest the recovery of function. Rather, it seems that relating age of lesion onset to other parameters, such as lesion side or size, has a greater and more reliable prognostic value. Another aim of the review is to analyze the effect that focal damage has on the dynamics of development. The fact that the effects of early damage might manifest themselves later in development, when the function in question is reaching a higher level of organization, underlines the importance of a longitudinal approach that assesses the developmental patterns of specific functions. Another issue discussed is the role of lesion side in determining specific cognitive impairment.(ABSTRACT TRUNCATED AT 400 WORDS)