BRAIN ORGANIZATION OF LANGUAGE AFTER EARLY UNILATERAL LESION - A PET STUDY

Neuropsychological studies suggest that good long-term language outcom e is possible following extensive early left-hemisphere damage. We exp lored the brain organization for language in children with early unila teral lesion, using [O-15]-water PET. In 12 patients with left lesion (LL) and 9 patients with right lesion (RL), cerebral blood how changes during listening to sentences and repetition were studied. A rightwar d shift of language activations in the LL group was found in perisylvi an areas and multiple other, mostly temporo-parietal, regions. The hyp othesis of intrahemispheric reorganization in the LL group found only limited support. The number of activated regions was overall greater i n the RL group. Unexpected findings included a stronger subcortical an d cerebellar language involvement in the RL group. We suggest that (a) early left lesion is associated with enhanced language participation of the right hemisphere in and beyond the classical language areas, an d (b) postlesional effects are in part additive (recruitment of noncan onical areas), in part subtractive (functional depression in areas nor mally involved in language). (C) 1998 Academic Press.