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 work life generally require mastery of this skill. That is why since childhood we are learning to give meaning to the words that we form through written language, something that although for an adult it may seem relatively simple if it has been done since childhood, it 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 correctly developed the ability to read lose this possibility for some reason, completely losing the ability to read. This circumstance corresponds to alexia, which we are going to talk about throughout this article.
The alexia: basic definition
Alexia is called a written language disorder characterized by the partial or complete loss of reading ability, this being produced by the appearance of some type of brain injury. It is therefore a secondary type of affectation, that is, derived from another alteration, which can even be interpreted as a symptom of it.
It is considered a type of visual agnosia, that is, the absence of recognition of some type of perceptible stimulation through sight. In the case at hand, the subject loses the ability to understand written words, making it impossible or at least assuming great difficulty to encode them in order to transform the spelling into a phoneme, although they have previously possessed this ability.
Types of alexia
Although alexia implies the loss of reading ability, it does not always appear in the same way, and there may also be other problems or starting from different deficits. Among the main types we can find
Alexia pure or without agraph
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 word blindness. A single frequently used word for the subject may be recognized.
It is not the most common, since it usually involves a bilateral involvement in such a way 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, lingual and / or angular gyrus, 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 neither read nor write. Anomia may also appear, having problems 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 the spelling or letters are passed to phonemes or sounds and vice versa, something necessary both to read and to write. It is also related to lesions in the parietals or in the fibers from the temporal and occipital lobes.
Alexia anterior or with aphasia
Also called frontal alexia, we are facing a circumstance in which not only alterations occur at the reading 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. It is usual that there are fewer problems with familiar words for the subject than in comparison to the rest of alexias.
Differentiation from 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 said ability, the cases of those who have never learned to do so being considerable like alexia. that is, illiteracy.
It is also relevant to differentiate it from 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 is a difficulty for reading and writing that it appears since childhood and in which there has never 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 is not derived from the absence of visual perception itself: the subject can see the words and his eyes work with enough precision to perceive them, the problem being the encoding and transformation of these into something significant.
Alexia is considered to be a type of agnosia and an impairment of literacy caused by some type of brain injury. But the causes of such an 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 gyrus to the fibers from the occipital or temporal lobes, through the lingual and fusiform gyrus, 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 the suffering of some type of cerebrovascular accident 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 areas affected, death of brain tissue can lead to loss of reading ability.
2. Head injury
Another classic reason for the appearance of alexia is the fact of having suffered some type of head trauma. Traffic accidents, work accidents or assaults are some of the causes that cause some type of alexia to appear.
3. Dementias and other neurodegenerative disorders
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 can appear in different phases 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 involved in the reading process.
5. Brain infections
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 facing a phenomenon derived from some type of brain injury, and in fact we may be facing 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 its implementation will require a multidisciplinary team in which disciplines such as neurology or psychology work, as well as other health or even social specialties.
The first thing is 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 level of treatment and can prevent a worsening (for example, if we are facing an infection or a tumor, these can grow and cause more damage).
It will be necessary to use an individualized rehabilitation program, with the use of speech 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 represent a limitation. It can also be important to work the affective sphere, self-concept and self-esteem, which can be altered by the presence of deficits.
- Junqué, C. and Barroso, J. (Coords.) (2009). Neuropsychology Manual. Madrid: Synthesis.
- Portellano, JA (2005). Introduction to neuropsychology. Madrid: McGraw Hill.