Alexia: what is it, types, symptoms, causes and treatment
The ability to read It is a fundamental skill in today's society. Academic and work life require, as a general rule, the 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 operations and mental transformations to be carried out successfully.
However, sometimes people who have possessed and have correctly developed the ability to read lose this possibility for some reason, completely losing the ability to read. This circumstance corresponds to the alexia , of which we are going to talk throughout this article.
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The alexia: basic definition
It receives the name of alexia a written language disorder characterized by the partial or complete loss of reading ability, this being caused by the appearance of some type of brain injury. It is therefore an affectation of a secondary type, that is to say derived from another alteration, which can even be interpreted as a symptom of this.
It is considered a type of visual agnosia, that is, the absence of recognition of some kind of stimulation perceptible through sight. In the case at hand, the subject loses the ability to understand written words , it being impossible or at least assuming a great difficulty to codify them in order to transform the spelling into a phoneme, although it has previously possessed such capacity.
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Types of alexia
Although the alexia implies the loss of reading ability does not always appear in the same way, there may also be other problems or starting from different deficits. Among the main types we can find
Alexia pure or without agraphia
This type of alexia is one in which only severe difficulties appear or the complete impossibility 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 blindness for words . It is possible that a single word of frequent use is recognized for the subject.
It is not the most common, since it usually involves a bilateral affectation in such a way that the visual information can not pass to the areas that interpret and generate the language, in the left hemisphere. It usually corresponds to problems in the occipital area of the brain , in the fusiform, lingual and / or angular turns, or the uncus.
Alexia central 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 not read or write. Anomia may also appear , having problems when identifying objects and visual stimuli beyond reading and writing.
This type of alexia usually corresponds to injuries in the angular turn, which is responsible for processing the information in such a way that the spelling or letters are passed on to phonemes or sounds and vice versa, something necessary both for reading and writing. It is also related to lesions in the parietals or in the fibers from the temporal and occipital lobes.
- Related article: "The lobes of the brain and its various functions"
Alexia previous or with aphasia
Also called frontal alexia, we are facing a circumstance in which not only alterations occur at the reader level but also in the production of 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 . Usually there are fewer problems with familiar words for the subject than in comparison to the rest of alexias.
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Differentiation with other situations
It is important to bear in mind that in alexia we are facing a situation in which the subject previously knew how to read and there has been a loss of this capacity, not being as considerable as alexia the cases of those people who have never learned to do so, that is, illiteracy.
It is also important to differentiate it from the evolutionary 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 an injury itself) in which there appears a difficulty for literacy that appears from childhood and in which never there has been a greater degree of capacity than the subject expresses at that moment (not being a loss but rather a difficulty).
Finally, it should be noted that alexia it is not derived from the absence of visual perception properly speaking: the subject can see the words and his eyes work with enough precision to perceive them, the problem being the codification and transformation of these into something significant.
It is considered that alexia is a type of agnosia and an alteration of the literacy generated by some type of brain injury. But the causes of such injury can vary greatly. It should also be borne in mind that the lesion can appear in different locations of the nervous system, from the angular and / or supramarginal turns to the fibers coming from the occipital or temporal lobes, passing through the lingual and fusiform turns, among others. Among the main causes of the appearance of alexia We can find the following events.
One of the main causes of alexia is suffering from some type of stroke or stroke, 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 affected areas, The death of brain tissue can cause the loss of reading ability .
2. Cranioencephalic trauma
Another classic reason for the appearance of the alexia is the fact of having suffered some type of traumatic brain injury. Traffic accidents, accidents at work or assaults are some of the causes that make some kind of alexia appear.
3. Dementias and other neurodegenerative disorders
The alexia can appear throughout the deterioration generated by some type of dementia, such as Alzheimer's, or other similar disorders. Depending on the disorder itself the difficulty, worsening and inability to read may appear in different phases of the disease .
- Related article: "Types of dementia: the 8 forms of loss of cognition"
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 involved in the reading process .
5. Brain infections
The alexia can also appear before 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 easy, considering that we are dealing with a phenomenon derived from some type of brain injury, and in fact we can face permanent damage. However, this does not imply that it is not possible to achieve different levels of recovery, depending on the areas injured or the degree of damage to the injury, or the compensation of functions.
The type of treatment will depend on these and other factors, and for its realization it will be necessary to a multidisciplinary team in which disciplines such as neurology or psychology work , in addition to other health or even social specialties.
The first will be to determine and treat the cause of the appearance of alexia. For the most part, an early diagnosis will allow a better work at the treatment level and can avoid a worsening (for example, if we are facing an infection or a tumor, these can grow and generate more damage).
It will be necessary use an individualized rehabilitation program , the use of language therapies and different types of cognitive stimulation being common. Psychoeducation will also be important both for people and for their environment, so that they can understand what has happened and that they know how to apply different means so that difficulties do not involve a limitation. It can also be important to work on the affective sphere, self-concept and self-esteem, which can be altered by the presence of deficits.
- Junqué, C. and Barroso, J. (Coords.) (2009). Manual of Neuropsychology. Madrid: Synthesis.
- Portellano, J.A. (2005). Introduction to neuropsychology. Madrid: McGraw Hill.