Acquired dyslexia and dysgraphia

Acquired dyslexia and dysgraphia refer to disturbances in reading and writing in a previously competent reader/writer subsequent to brain damage (as in stroke or closed head injury). Contemporary studies of acquired dyslexia and dysgraphia emphasize patterns of preserved and impaired abilities in order to understand the mental processing architecture in normals. This objective has been explicitly stated in the program of modern cognitive neuropsychology, which was established especially by the new approach taken to acquired disorders of written language. In the previous, syndrome-oriented, neuropsychological paradigm, the focus of attention was predominantly on acquired disorders of the spoken language system (aphasia), their classification, and their lesion correlation. Because reading and writing skills develop after the acquisition of a spoken language system, and their normal development in fact crucially depends on the successful development of spoken language abilities, the general view was that written language does not have a system of its own. As a consequence, the majority of written language disorders was considered to be a consequence of the impairment of the system of spoken language (see De Bleser & Luzzatti, 1989 for a review). The only classical modality-specific impairment of written language was alexia, a total impairment of reading already affecting letter-level processing, with and without agraphia (see below). This view radically changed with the introduction of cognitive neuropsychological models of reading. These were based on models of normal reading that introduced the view that unimpaired readers of alphabetic scripts, in which the smallest written unit corresponds approximately to a phoneme, have at least two routines for deriving the phonology of written words: a lexical route, which allows the association of whole-word pronunciations from stored lexical knowledge to a sight vocabulary, and a nonlexical routine, in which phonemes corresponding to a word’s graphemes are sounded out one by one.