Alexia: what it is, types, symptoms, causes and treatment
This neurological disorder makes it impossible or difficult to read, despite having good vision.
The ability to read is a fundamental skill in today's society. Academic and working life generally requires mastery of this skill. That is why since childhood we are learning to give meaning to the words we form through written language, something that although for an adult may seem relatively simple if it has been done since childhood requires a high level of processing and a large number of mental operations and transformations to be carried out successfully.
However, sometimes people who have possessed and correctly developed the ability to read lose for some reason this possibility, completely losing the ability to read. This circumstance corresponds to alexia, which we will discuss in this article.which we are going to talk about in this article.
Alexia: basic definition
It receives the name of alexia a written language disorder characterized by the partial or complete loss of the capacity of reading, being this produced by the appearance of some type of cerebral lesion. It is therefore a secondary type of impairment, i.e. derived from another disorder, which can even be interpreted as a symptom of the latter.
It is considered a type of visual agnosia, i.e. the absence of recognition of some type of stimulation perceptible through sight. In the present case, the subject loses the ability to understand written wordsIt is impossible or at least a great difficulty to encode them in order to transform the spelling into a phoneme, although he/she has previously had this ability.
Types of alexia
Although alexia implies the loss of the ability to read, it does not always appear in the same way, as there may also be other problems or different deficits. Among the main types we can find
Pure alexia or without agraphia
This type of alexia is one in which only severe difficulties or complete impossibility appear in the visual recognition of letters or words, although the subject can write correctly (despite not being able to understand what he has written). It is also called word blindness.. It is possible that some single words of frequent use for the subject may be recognized.
It is not the most common, since it usually involves bilateral involvement so that visual information cannot pass to the areas that interpret and generate language, in the left hemisphere. It usually corresponds to problems in the occipital area of the brain, in the fusiform gyrus, in the fusiform gyrus and in the occipital gyrus.It usually corresponds to problems in the fusiform, lingual and/or angular gyrus, or the uncus.
Central Alexia or with agraphia
As in the previous case we find an alteration and impossibility or great difficulty in the recognition of written words, but also in their production. In other words, in this case we find that the subject can neither read nor write. It is possible that anomia may also appearhaving problems in identifying objects and visual stimuli beyond reading and writing.
This type of alexia usually corresponds to lesions in the angular gyrus, which is responsible for processing information in such a way that spelling or letters are converted into phonemes or sounds and vice versa, which is necessary for both reading and writing. It is also related to parietal lesions or in the fibers coming from the temporal and occipital lobes.
Anterior alexia or with aphasia
Also called frontal alexia, we are in front of a circumstance in which not only alterations are produced at reader level but also in the production of the speech. In this case the lesion is generally produced at a more frontal level, its functionality being similar to that of a subject with Broca's aphasia.. There are usually fewer problems with words familiar to the subject than in comparison with other alexias.
Differentiation with other situations
It is important to bear in mind that in alexia we are dealing with a situation in which the subject already knew how to read and there has been a loss of this ability, and the cases of those people who have never learned to read, that is, illiteracy, are not considered as alexia.
It is also relevant to differentiate it from developmental dyslexia, which would be a disorder of neurodevelopmental dyslexia.which would be that neurodevelopmental disorder (which implies that at the neuronal level what exists is an atypical organization of brain development and not a lesion itself) in which there is a difficulty in reading and writing that appears since childhood and in which there has never been a greater degree of ability than that which the subject expresses at that time (not being a loss but rather a difficulty).
Finally, it is worth mentioning that alexia is not derived from the absence of visual perception per se: the subject can see the words and his eyes function accurately enough to perceive them. per se: the subject can see the words and his eyes work accurately enough to perceive them, the problem being the encoding and transformation of the words into something meaningful.
Possible causes
Alexia is considered to be a type of agnosia and an alteration of reading and writing generated by some kind of brain injury. But the causes of such injury can vary greatly. It must also be taken into account that the lesion can appear in different locations of the nervous system, from the angular and/or supramarginal gyrus to the fibers coming from the occipital or temporal lobes, passing through the lingual and fusiform gyrus among others. Among the main causes of onset of alexia, we can find the following events. we can find the following events.
1. Cerebrovascular accident
One of the main causes of alexia is a stroke, whether we are talking about ischemia (blockage of the Blood vessel that prevents blood from reaching certain areas) or hemorrhage (rupture of the vessel). Depending on the areas affected, the death of the brain tissue may result in the loss of the ability to read and write..
2. Traumatic brain injury
Another classic reason for the onset of alexia is the fact of having suffered some kind of traumatic brain injury. Traffic accidents, accidents at work or aggressions are some of the causes that can cause some type of alexia to appear.
3. Dementias and other neurodegenerative disorders
Alexia may appear along the deterioration generated by some type of dementia, such as Alzheimer's disease, or other similar disorders. Depending on the disorder itself, the difficulty, worsening and inability to read may appear at different stages of the disease. may appear at different stages of the disease.
4. Brain tumor
Another possible cause of alexia is found in the appearance of brain tumors that affect, pinch or compress the brain areas and nerve fibers. brain areas and nerve fibers involved in the reading process..
5. Brain infections
Alexia can also appear in the presence of certain infectious processes that end up affecting the brain. Some typical ones are meningitis or encephalitis..
Treatment of alexia
The treatment of alexia is not simple, taking into account that we are facing a phenomenon derived from some type of brain injury, and in fact we may be facing a permanent damage. However, this does not imply that it is not possible to achieve different levels of recovery, depending on the injured areas or the degree of involvement of the injury, or compensation of functions.
The type of treatment will depend on these and other factors, and for its implementation will require a multidisciplinary team working in disciplines such as neurology or psychology, as well as other health specialties.and other health or even social specialties.
The first step will be to determine and treat the cause of the onset of alexia. In most cases, an early diagnosis will allow a better work at the treatment level and can prevent a worsening (for example, if we are facing an infection or a tumor, these can grow and generate more damage).
It will be necessary to use of an individualized rehabilitation programIt is common to use speech therapies and different types of cognitive stimulation. Psychoeducation will also be important for both the person and his or her environment, so that they can understand what has happened and know how to apply different means so that the difficulties do not become a limitation. It may also be important to work on the affective sphere, self-concept and self-esteem, which may be altered by the presence of deficits.
Bibliographical references:
- Junqué, C. and Barroso, J. (Coords.) (2009). Manual de Neuropsicología. Madrid: Síntesis.
- Portellano, J.A. (2005). Introduction to neuropsychology. Madrid: McGraw Hill.
(Updated at Apr 14 / 2024)