Basic reading skills and dyslexia: three decades following right versus left hemispherectomy for childhood-onset intractable epilepsy.

Dyslexia was explored within the framework of three explanations for language functioning following hemispherectomy (i.e., equipotentiality, hemispheric specialization, and crowding hypothesis/hierarchy of specialized functions) and the extent to which these models explain reading performance in S.M. (age 48, right hemispherectomy) and J.H. (age 49, left hemispherectomy). Basic reading performance was evaluated by assessing whole-word and subword reading. Both participants displayed severely impaired reading performance on pseudohomophones (e.g., WUN), signifying poor subword reading. However, J.H. (remaining right hemisphere) also demonstrated impairments in reading exception words (e.g., ONE), suggestive of poor whole-word reading. Thus, although S.M. clearly demonstrated phonological dyslexia and retention of the priority whole-word reading skills, J.H. presented with deficits more characteristic of mixed dyslexia. Taken as a whole, we suggest that some modification of the hierarchy of specialized functioning model and crowding hypothesis is needed, including stipulations about hemispheric specialization, to more accurately accommodate the present data.