Development of above normal language and intelligence 21 years after left hemispherectomy.

Neuropsychologic follow-up studies of a 5 1/2-year-old boy who had left hemispherectomy for seizures showed that he had developed superior language and intellectual abilities. These findings contrast with recent reports indicating that the plasticity of the nervous system may have been overrated and contradict reports of restricted development of language functions after left and of nonlanguage functions after right hemispherectomy for perinatal lateralized brain lesions. Following removal of the left hemisphere, including "the classical language zones," the right hemisphere and other intact residual structures may provide the necessary substrata for the development of above normal adult language and intellectual capacities.