Stroke and traumatic brain injury, among many other causes, can lead to impaired understanding or production of spoken and written language if they damage the brain structures or connections that control these functions. We call these disorders “aphasias”.
In this article we will describe the main symptoms and most common causes of Wernicke’s aphasia, Which is characterized by a pronounced deficit in understanding the language and other problems associated with it.
What are aphasias?
Aphasias are language disorders that occur as a result of brain damage. Depending on the regions and neural pathways affected, very different signs can appear, resulting in different types of aphasia.
However, in many cases the deficits combine differentiated alterations or occur in a generalized manner. When the latter occurs, usually as a result of massive damage to the left hemisphere of the brain, it is called global or total aphasia.
Some lthe basic criteria used to classify aphasias these are the degree of verbal fluency, the quality of articulation of phonemes, the ability to understand and repeat the words spoken by other people, the correctness of the syntax and the presence of involuntary or erroneous phonemes.
Since the brain structures that control the production and understanding of speech correspond to the areas responsible for literacy, the deficits inherent in aphasia do not appear only in relation to spoken language but also in writing.
Description of Wernicke’s aphasia
Wernicke’s aphasia is mainly characterized by the presence of difficulty understanding the language, Which in turn leads to an inability to repeat the words of others; this criterion is very relevant in the neuropsychological evaluation of aphasias.
On the contrary, and unlike in other aphasias (especially in Broca), Wernicke maintains the fluency of speech – in fact, in many cases, he becomes excessively fluid. However, frequent errors do appear and patients are usually not aware of it.
According to Aleksandr Luria, who calls this disorder “acoustic-agnostic aphasia,” the key problem with Wernicke’s aphasia is in the analysis and synthesis of phonemes during the speech perception process; the deficit is due to injuries in the secondary areas of the tongue, which control these functions.
This kind of aphasia it is also known as “receptive”, “sensory”, “comprehension”, “acoustic”, “syntactic” and “central” aphasia. These adjectives refer to some of the most defining characteristics of Wernicke’s aphasia, which we will describe in detail below.
It is important to differentiate Wernicke’s aphasia from Wernicke-Korsakoff syndrome, a disorder that affects memory and other cognitive functions and usually occurs as a result of chronic alcoholism or other factors that cause deficiency in thiamine (vitamin B1)), such as malnutrition.
Main symptoms and characteristics
Wernicke’s aphasia can be identified primarily from the speech of the affected person. Although this it has normal rhythm, fluidity and prosodyIt is characterized by frequent repetitions, errors and the inclusion of meaningless words and phrases.
The most characteristic symptoms and traits of Wernicke’s aphasia are associated with receptive deficits, which prevent proper language processing. The main clinical features of this disorder are as follows:
- Severe impairment in hearing comprehension and language reading.
- Inability to correctly repeat words and sentences.
- Difficulty remembering or pronouncing the names of objects and living things (anomie).
- Maintenance or excess of fluency in speaking and writing.
- Absence of alterations in the articulation of phonemes.
- Substitution of words by others with a similar meaning (semantic paraphrases).
- Use of meaningless words (neologisms).
- Incomprehensible and incoherent speech and writing by the so-called “word salad”.
- Lack of awareness of linguistic errors (anosognosia).
Causes of this disorder
Aphasias they usually occur as a result of strokesWhile any other type of factor causing damage to certain regions of the brain is likely to cause aphasia: cranioencephalic trauma, brain tumors, neurodegenerative disorders, viral infections …
In the case of Wernicke’s aphasia, the lesions are localized at the posterior part of the superior gyrus of the left temporal lobe. Previously, this disorder was specifically associated with damage to the left upper first temporal gyrus, which corresponds to zone 22 of the Brodmann classification or “Wernicke’s zone”.
Damage in this section of the superior temporal gyrus not only affects the regions of the frontal lobe directly involved in the tongue, but also isolates them from most of the temporal, parietal and occipital lobes.