Additional physiologic data from functional imaging studies support the presence of an abnormal temporoparietal cortex in dyslexics. These regions, particularly the posterior portion of the superior temporal, angular, and supramarginal gyri, are selectively activated during reading in normal individuals but not in dyslexics, who activate very restricted regions of the cerebral hemisphere, mainly the Broca area. In addition, they recruit other areas not normally activated during reading, such as the inferior frontal regions. It is noteworthy that Simos and coworkers were able to show that these aberrant patterns (using functional MRI) normalized after several weeks of intensive training. If nothing else, these findings validate the localization of the functional problem in the dominant temporoparietal area, and support the notion that developmental dyslexia is susceptible to improvement by proper training.
Treatment The steady practice (many hours per week) of a cooperative and motivated child by a skillful teacher over an extended period slowly overcomes the handicap and enables an otherwise intelligent child to read at grade level and to follow a regular program of education. The Orton phonologic method has been one of the most widely used over the years (for details, see Rosenberger). Secondary school and college students with reading deficits successfully resort to tape recorders, tutorial aids, and laptop computers that allow for review of material after classes.
Developmental writing disorders differ from dyslexia in having both linguistic and motor (orthographic) aspects. As indicated earlier, dysgraphias are present in many dyslexic children and may be combined with difficulty in calculation (so-called developmental Gerstmann syndrome). Two forms of dysgraphia have been distinguished. In one there is good spontaneous handwriting and formation of letters and spacing but miswriting of dictated words (linguistic dysgraphia). In the other, there are reversals of letters and letter order and poor alignment (mechanical dysgraphia). It is this latter type that seems to us to be the genuine, or at least the purer, dysgraphia.
This disorder, like dyslexia, usually becomes evident in the first few years of grade school, when the child is challenged by tasks of adding and subtracting and, later, multiplying and dividing. In some instances there is an evident disorder in the spatial arrangements of numbers that has been termed “anarithmetia” as noted in Chap. 21 (supposedly a right hemispheral fault). In others, there is a lexical–graphical abnormality (naming and reading the names of numbers) akin to aphasia.
Probably most of what has been said about the treatment of developmental dyslexia applies to acalculia and agraphia. The usual type of conventional classroom work does little to increase the child’s proficiency in writing and arithmetic, but special tutoring and drills aid the student to some extent. All of these impairments may be associated with hyperactivity and attentional defects, as described below (Denckla et al).
In direct contrast to the conditions discussed above, precocious reading and calculating abilities have also been identified. A 2or 3-year-old child may read with the skill of an average adult. Extraordinary facility with numbers (mathematical prodigies) and memorization ability (eidetic imagery) are comparable traits. One of these special abilities may be observed in a child with a mild form of autism (Asperger syndrome, see Chap. 37). Such children exhibit great skill in performing particular mathematical tricks but are unable to solve simple arithmetical problems or to understand the meaning of numbers (“savant syndrome”). In the child with Williams syndrome, language and sometimes musical skills are not so much precocious as relatively normal in comparison to the overall mental deficiency, indicating that not all forms of cognitive delay impair language skills.