Alexia and agraphia: written language disorders due to brain injury
The use of language is one of the main capacities of the human being . The fact of dominating it more or less influences how we relate to other people, how we see ourselves and even how we think.
Perhaps that is why there is a side of neuropsychology very interested in language disorders, among which the most known are dyslexia and aphasia. However, there are also some others, such as alexia and the agraphia .
What is alexia?
Said in a very summarized way, alexia is a loss of the ability to read correctly that is due to an injury to the encephalon . Therefore, the term alexia refers to a range of alterations in reading that are caused by brain damage.
Alexia differs from dyslexia in that in the latter the reading problems appear without being able to identify wound marks in the neuronal tissue of brain regions associated with language. If in the alexia the disorder appears because of the acquired damage, in dyslexia the explanation has to do more with the way in which the brain develops during childhood, with a genetic component and with a learning dynamic that gives problems. This explains that alexia is also known as acquired dyslexia.
Also, as it happens in all language disorders, alexia can occur in milder forms and in more severe ones in which the person is totally unable to read.
What is agraphy?
Agraphy is the inability to write correctly whose cause is also a brain injury .
Normally, agraphia appears together with other language disorders (especially with aphasias and alexias). Therefore, cases of pure agraphia are very rare in which the only difficulty related to language affects writing and no other ability.
The types of alexia
As the concept of alexia is very broad, in neuropsychology and psycholinguistics many subcategories are used to differentiate the ways in which this disorder can occur and have it easier to intervene on a case-by-case basis (besides allowing to carry out research in which it is observed how different injuries produce different effects).
1. Alexia without agraphia, or pure alexia
As the name suggests, pure alexia serves to identify cases in which there is only one inability to read, but not to write . People who experience it see the letters as if they were simple drawings, and are not able to translate these visual signals into phonemes. Therefore, and although it seems strange, in cases where alexia is diagnosed without agraphia the affected person is unable to understand what she herself has written.
It is the least common type of alexia, since for this to occur the lesions have to affect the two lobes of the brain and make the visual information that is collected from both eyes can not pass to the left side of the brain to be processed by the language areas, while those that intervene in the production of written language remain intact and connected to each other.
2. Alexia with agraphia, or central
People who experience alexia with agraphia they have serious problems both reading and writing .
This type of alexia is also known as alexia angular, because it affects an area of the brain called angular gyration. In the angular rotation, which is located in the lower part of the parietal lobe (usually on the left side of the brain), it is responsible among other things for converting letters into sounds and vice versa, and therefore it is very likely that an injury that destroys this area or isolates it from the rest of the cortex produces alexia with agraphia.
3. Alexia anterior, or frontal
Unlike what happens in the other two types of alexia, in which the lesion occurs in areas of the brain near the nape, the anterior alexia is caused by a lesion that mainly affects the frontal lobe, in the area near the left temple It is an alexia associated with Broca's aphasia, although when talking about frontal alexia, problems in reading are usually more serious than those related to the rest of the language's functions.
In patients in whom this type of alexia produces milder symptoms, the main difficulties have to do with problems when understanding the syntactic relationships between the words that are read. When the alexia is more severe, they can not identify words that are spelled, or name the letters of a short phrase. However, something that distinguishes frontal alexia from the other two categories is that in this there is a greater facility when reading words that are familiar.
How can alexia be treated?
The alexias are always produced by injuries in the brain, and therefore any treatment initiative must be supervised by specialists whose scope is related to neurology and who can provide a personalized service.
- Junqué, C. and Barroso, J. (Coords.) (2009). Manual of Neuropsychology. Madrid: Synthesis.
- Moore, M. M., Brendel, P. C., Fiez, J. A. (2014). Reading faces: Investigating the use of a novel face-based orthography in acquired alexia.Brain and Language, 129, pp.7-13.
- Pflugshaupt, T., Gutbrod, K., Wurtz, P., Von Wartburg, R., Nyffeler, T., De Haan, B., Karnath, H., Mueri, R. M. (2009). About the Role of Visual Field Defects in Pure Alexia. Brain, 132 (7), pp. 1907 - 1917.