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Aphasias

Aphasias

A language disorder is an impediment that makes it difficult for someone to find the right words and form clear sentences when speaking. It can also make it difficult to understand what another person says. You may have difficulty understanding what others say, to express your thoughts with words, or both.

It is important to keep in mind that a language disorder is not the same as a hearing problem or speech disorder. Children with language disorders generally have no problem hearing or speaking words. Your challenge is to master and apply the rules of language, such as grammar.

Language is a complex function of human beings that results from the coordinated activity between neural networks distributed by the cerebral cortex and subcortical areas. However, this does not eliminate the possibility that an injury to a certain area of ​​the brain can cause a specific language disorder. We will explain below what are the main language disorders due to lesions in the brain.

Content

  • 1 Aphasias
    • 1.1 Global aphasia
    • 1.2 Drill Aphasia
    • 1.3 Wernicke's Aphasia
    • 1.4 Driving aphasia
    • 1.5 Transcortical sensory aphasia
    • 1.6 Transcortical motor aphasia
    • 1.7 Mixed transcortical aphasia
    • 1.8 Anomic aphasia
    • 1.9 Alterations in literacy
    • 1.10 Alexia later
    • 1.11 Central Alexia
    • 1.12 Alexia previous
    • 1.13 Aphasic Agrafia
    • 1.14 Pure Agrafia
  • 2 Other alterations
    • 2.1 Aprosodias
    • 2.2 Calculi

Aphasias

Aphasia is a language disorder that affects speech production or comprehension and the ability to read or write. Aphasia is always due to a lesion in the brain, most often as a result of a cerebral vascular accident (AVC), particularly in older people. But brain injuries that cause aphasia can also be from head trauma, a tumor or an infection.

Depending on the location of the lesion, there will be different types of aphasia.

Global aphasia

This is the most severe form of aphasia, and those affected can produce few recognizable words and understand little or no spoken language.People with global aphasia cannot read or write. Global aphasia can often be seen immediately after the patient has had a stroke and can improve quickly if the damage has not been too extensive. However, with increased brain damage, severe and lasting disability can occur.

Symptoms of this aphasia include: poorly spoken speech, severe impaired comprehension, impaired repetition and anomie. Sometimes the automatic language is preserved (count, recite the days of the week, etc.). These patients may evolve towards Broca's aphasia, since the comprehension deficit usually has a better evolution.

Broca's Aphasia

This aphasia is caused by the Broca area injury and adjacent areas of the frontal cortex, the insula and subcortical structures of the left hemisphere.

In this form of aphasia, speech ability is severely reduced and limited mainly to short sentences of less than four words. Access to vocabulary is very limited and the formation of sounds by people with Broca's aphasia is often laborious and clumsy. The person can understand speech relatively well and be able to read, but it should be limited in writing. Broca's aphasia is often referred to as a "non-fluid aphasia" due to the quality of hesitant and forceful voice.

It is characterized by the following:

  • Speak little fluently.
  • Distortion in the production of phonemes.
  • Agramatism Mainly nouns and, to a lesser extent, verbs and adjectives are used. Grammar words (conjunctions, prepositions, verbal endings, etc.) disappear. This is called telegraphic speech. For example: eat apple desserts for I have eaten an apple for dessert.
  • Understanding relatively preserved, except when it depends on the correct interpretation of the grammar rules. For example, in passive phrases: the child was hit by the ass.

Wernicke's Aphasia

This aphasia is due to the lesion of the left posterior temporal region, that is, the Wernicke area. The lesion often includes the primary auditory cortex, other regions of the temporal lobe, parietal regions (such as angular gyrus or supramarginal gyrus) or white subcortical substance.

In this form of aphasia, what is mainly affected is the ability to capture the meaning of the words, while the ease of producing speech is not greatly affected. Therefore, Wernicke's aphasia is known as a 'fluid aphasia'. However, speech is far from normal. The sentences do not come together and irrelevant words interfere, sometimes to the point of jargon, in severe cases. Reading and writing are often seriously affected.

It is characterized by the following:

  • Speak fluently Sometimes excessively fluid (logorrhea).
  • High incidence of parafasia (substitute one word for another) and neologisms (use non-existent words). Sometimes, speech is totally unintelligible (aphasic jargon).
  • Anomie (inability to say the name of an object).
  • Alteration of repetition.
  • Significant comprehension deficit, especially at a syntactic and semantic level (meaning of words).

Driving aphasia

Driving aphasia observes when injures the connection between the anterior and posterior components of the language, that is, when the arcuate fascicle of the left hemisphere is injured. The lesion usually affects the supramarginal gyrus and the underlying white substance, or the primary auditory cortex, the insular cortex and underlying white matter.

It is characterized by the following:

  • Speak fluently and with paraphasia.
  • Naming problems (anomie).
  • Serious alteration of repetition. Although the patient understands what he is told, he makes repetitive paraphase substitutions.
  • Understanding preserved.

Transcortical sensory aphasia

The primary auditory cortex and Wernicke area are not affected. It is due to the lesion of other temporal zones of the left hemisphere, and may also cover part of the visual cortex. It can also be of subcortical origin.

It is characterized by the following:

  • Speak fluently and with paraphasia.
  • Affectation of understanding.
  • Relatively preserved repetition. Ecolalia is often observed (repetition of everything another person says).

Transcortical motor aphasia

This aphasia is due to the lesion of prefrontal cortex structures surrounding the frontal operculum, premotor areas and / or the underlying white substance of the left hemisphere.

It is characterized by the following:

  • Speak not fluently.
  • Naming difficulties (usually need phonemic help).
  • Understanding is relatively preserved.
  • The repetition is relatively preserved.

Mixed transcortical aphasia

This aphasia is a combination of the two types of transcortical aphasias described above. In general, the perisylvian areas are preserved and other regions of the temporal, parietal and frontal lobes of the left hemisphere are affected.

It is characterized by the following:

  • Speak not fluently.
  • Alteration of the denomination.
  • Impaired understanding
  • Relatively preserved repetition. Ecolalias are often observed.

This table has been called language zone isolation, since although the structures of the expressive and receptive pole of language (Broca and Wernicke areas, respectively) are intact, they have lost their connection with the rest of the cortex areas.

This type of aphasia shows us how Broca's area is necessary, but not sufficient, for linguistic production, and the same goes for Wernicke's area for comprehension. Repetition, on the other hand, seems to be able to develop correctly only with these structures, provided that the connection between them is intact.

Anomic aphasia

This term applies to people who are left with a persistent inability to find words for things they want to talk about, particularly significant nouns and verbs. As a result, his speech, although fluid in grammatical form, is full of vague circumlocutions and expressions of frustration. They understand speech well and, in most cases, read properly. The difficulty in finding words is as evident in writing as in speech.

In principle this type of aphasia was associated with lesions of the parietal lobe and lower regions of the temporal lobe of the left hemisphere. As we have seen, however, anomie is a common symptom to many types of aphasias, so its anatomical location can also be diverse.

This is the mildest and most frequent type of aphasia, since most recovered aphasic patients end up with a residual deficit in the denomination. It is characterized by the following:

  • Speak fluently and without paraphasia.
  • Repetition preserved.
  • Understanding preserved.
  • Variable alteration of the denomination. In the most serious cases empty speech is observed (frequent use of unspecific words, such as thing, that, etc.), use of circumlocutions and a significant number of pauses to search for the right word.

Main aphasic syndromes with their clinical characteristics. In most cases, reading comprehension and writing are also affected.

The main characteristics of aphasic disorders are summarized in the adjacent table.

Literacy Alterations

The term alexia refers to the reading impairment as a result of a brain injury.

In both cases we talk about subjects who had previously acquired the ability to read and write previously. When reading or writing disorders appear during development, we will talk about dyslexia and dysgraphia.

The term agrafia refers to the alteration of writing as a result of a brain injury.

Alexia later

Also known as alexia pura or alexia without agraph, this is the type of alexia less frequent but more spectacular, since the patient loses the ability to read, but retains the writing.

We will talk alexia verbal when the subject can read the letters one by one, but cannot read words. If the opposite pattern is given, that is, preserved word reading but altered letter reading, we will talk about alexia literal. When it is impossible to read both letters and words, we will talk about alexia global.

It is usually characterized by an inability to read words (alexia verbal), while reading letters is preserved. The writing is normal, except for the copy, which is done with difficulty. The reading of numbers, like that of letters, is usually preserved.

The lesion responsible for this alexia is the disconnection between the visual areas and the structures responsible for reading in the left hemisphere, such as angular rotation. Therefore, a lesion in the occipital lobe of the left hemisphere is necessary that affects the posterior part of the corpus callosum and, thus, also prevents access to visual information from the right hemisphere.

Central alexia

It is always accompanied by agrafia (alexia with agrafia). Alexia is global, that is, the ability to read individual words and letters is lost. The lesion is usually limited to angular rotation. If the lesion extends beyond the angular gyrus, it is usually accompanied by Wernicke's aphasia, transcortical sensory aphasia or anomic aphasia.

Previous Alexia

This alexia is the one that accompanies Broca's aphasia. It is characterized by literal alexia (inability to read individual letters) and syntactic alexia, or inability to understand the function of grammatical elements. Alterations in writing are frequent. The responsible lesion is the same as in Broca's aphasia.

Aphasia

Like talking about aphasias we called parafasia to the substitution of one word for another, we will call paralexias the parafasias that are observed in the reading and paragraphs those that are observed in the writing.

In most cases, Agrafia appears in the context of an aphasia, so the characteristics of agrafia depend on the characteristics of aphasia. Thus, non-flowing aphasias, such as Broca's or transcortical motor, are accompanied by difficult writing, with agramatism and spelling alterations. Flowing aphasias, such as Wenicke or transcortical sensory, on the other hand, are accompanied by an easy writing, but of limited content and with abundant presence of paragraphs.

Pure photography

Pure agraphia is an alteration of writing that is not accompanied by other language disorders. Has been related to lesions of the upper left posterior parietal lobe, and it has been proposed that this area could be key to integrate language with the sensorimotor function necessary for writing. It is a very rare disorder.

Other alterations

Aprosodias

The term prosody refers to those aspects of language such as intonation, melody, pauses or emphasis.

We can talk about two types of prosody:

  • Linguistic prosody: refers to the intonation that allows to differentiate an interrogative phrase from a declarative one (intrinsic prosody) and the emphasis that can be given to certain words to give a special meaning in the phrase (intellectual prosody).
  • Emotional prosody: is one that allows you to express joy, fear, surprise or any other emotion.

The term aprosodia refers to the loss or alteration of the ability to express and / or understand the prosodic aspects of language (linguistic or emotional) as a result of acquired brain damage usually located in the perisilvian region of the right hemisphere.

Acalculias

The term acalculia refers to the inability, total or partial, to perform arithmetic calculations consequence of acquired brain damage.

It may be a consequence of a specific alexia or agrafia for numbers, or in the case of primary acalculia, a consequence of an inability to perform arithmetic operations (anarithmetic). Acalculias are usually observed when you are injured the back of the left hemisphere.

Acalculia often accompanies language disorders.

References

Bradford, H.F. (1988). Fundamentals of neurochemistry. Barcelona: Labor.

Carpenter, M.B. (1994). Neuroanatomy Fundamentals Buenos Aires: Panamerican Editorial.

Delgado, J.M .; Ferrús, A .; Mora, F .; Blonde, F.J. (eds) (1998). Neuroscience Manual. Madrid: Synthesis.

Diamond, M.C .; Scheibel, A.B. and Elson, L.M. (nineteen ninety six). The human brain Work book. Barcelona: Ariel.

Guyton, A.C. (1994) Anatomy and physiology of the nervous system. Basic Neuroscience Madrid: Pan American Medical Editorial.

Kandel, E.R .; Shwartz, J.H. and Jessell, T.M. (eds) (1997) Neuroscience and Behavior. Madrid: Prentice Hall.

Martin, J.H. (1998) Neuroanatomy. Madrid: Prentice Hall.

Nolte, J. (1994) The human brain: introduction to functional anatomy. Madrid: Mosby-Doyma.

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