The occasional "independence" of dyslexia and dysgraphia from dysphasia.

In spite of the opportunity afforded by neurological cases for the study of the association of reading, writing, and spoken speech disorders, there is little agreement on the question whether these disabilities may exist independently or are necessarily parts of a general language disturbance. Where a disorder of reading has been found to be the major disability it has been accepted by some authors as a partial agnosia or a selective symbolic defect (Holmes, 1950; Symonds, 1953; Brain, 1955). On the other hand Critchley (1953) has held that such a dyslexia forms part of a more general disorder of language, as shown by the concomitant minor grades of speech defect. Other authors have sought to explain similar cases of reading disorder on the basis of fluctuating visual sensory efficiency (Beringer and Stein, 1930), of visual disorientation (Martin, 1954), or of alterations of eye movements (Warringtonand Zangwill, 1957). However, another disability seen even more frequently in association with dyslexia, defective identification of colours, has not been thought to give rise to the disorder of reading. Dysgraphia has been accepted by some authors (e.g., Gerstman, 1940) as a disability that can be seen without disturbances of spoken speech and reading. Critchley (1953) has sought to explain this form of dysgraphia as a disability of execution, a dyspraxia for writing. Again, it is noteworthy that the other features of the Gerstman syndromedyscalculia, finger agnosia, and right-left disorientation-are not invoked to explain the dysgraphia. It is, moreover, plausible that these are the results of proximity of functional areas rather than bearing any functional inter-relationship. In the present paper we wish to present further evidence for the occasional "independence" of dyslexia and dysgraphia from dysphasia, first, by a conventional detailed report of one patient; and second, by a survey of a series of unselected cases of language disability. For this purpose we refer to dyslexia as the inability to read correctly words and letters aloud; dysgraphia, as the inability to write correctly on paper; and dysphasia, as a defect of spoken speech as conventionally assessed by clinical testing.