Alexia and agraphia: written language impairment due to brain injury

We explain the alterations in writing caused by lesions in the brain.

The use of language is one of the main capabilities of human beings.. The fact of mastering 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 best known are dyslexia and aphasia. However, there are also some other disorders, such as alexia and agraphia.

What is alexia?

To put it very succinctly alexia is a loss of the ability to read correctly that is due to a lesion in the brain.. Therefore, the term alexia refers to a range of reading disorders caused by brain damage.

Alexia differs from dyslexia in that in dyslexia, reading problems appear without the latter, the reading problems appear without having been able to identify marks of injury in the neural tissue of the brain regions associated with language. of the brain regions associated with language. If in alexia the disorder appears as a result of acquired damage, in dyslexia the explanation has more to do with the way in which the brain develops during childhood, with a genetic component and with a learning dynamic that causes problems. This explains why alexia is also known as acquired dyslexia.

In addition, as with all language disorders, alexia can present in different forms, as with all language disorders, alexia can present in milder forms and in more severe forms where the in which the person is totally unable to read.

What is agraphia?

Agraphia is the inability to write correctly, which is also caused by a brain injury.. 

Usually, agraphia appears in conjunction with other language disorders (especially aphasia and alexia). Therefore, cases of pure agraphia in which the only language-related difficulty affects writing and no other ability are very rare.

Types of alexia

As the concept of alexia is very broad, many subcategories are used in neuropsychology and psycholinguistics to differentiate the forms in which this disorder can present itself and to make it easier to intervene on a case-by-case basis (as well as to carry out research to see how different lesions produce different effects).

Alexia without agraphia, or pure alexia

As the name suggests pure alexia is used to identify cases in which there is only an inability to read, but no inability to write.. People who experience it see letters as if they were simple drawings, and are not able to translate these visual signals into phonemes. Therefore, and although it may seem rare, in cases where alexia without agraphia is diagnosed, the affected person is unable to understand what he or she has written.

This is the least common type of alexia, since for it to occur the lesions must affect both lobes of the brain and mean that the visual information collected from both eyes cannot pass to the left side of the brain to be processed by the language areas, while those involved in the production of written language remain intact and connected to each other.

2. Alexia with agraphia, or central

Individuals who experience alexia with agraphia have serious problems with both reading and writing..

This type of alexia is also known as angular alexiaIt affects an area of the brain called the angular gyrus. The angular gyrus, which is located in the lower part of the parietal lobe (usually on the left side of the brain), is responsible, among other things, for converting letters into sounds and vice versa, and therefore it is very likely that a lesion that destroys this area or isolates it from the rest of the cortex will produce alexia with agraphia.

3. Anterior, or frontal, alexia

Unlike the other two types of alexia, in which the lesion occurs in areas of the brain near the nape of the neck, 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, reading problems are usually more severe than those related to other language functions.

In patients in whom this type of alexia produces milder symptoms, the main difficulties have to do with problems in understanding the syntactic relationships between the words being read. When the alexia is more severe, they cannot identify words that are spelled out to them, nor can they name the letters in a short sentence. However, one thing that distinguishes frontal alexia from the other two categories is that frontal alexia has an easier time reading familiar words.

How can alexia be treated?

Alexias are always caused by lesions in the brain, and therefore any treatment initiative should be supervised by specialists whose field is related to neurology and who can provide a personalized service.

Bibliographic references

• Junqué, C. and Barroso, J. (Coords.) (2009). Manual de Neuropsicología. Madrid: Síntesis.
• 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.