Strokes and head injuries, among many other causes, can lead to alterations in the understanding or production of spoken and written language if they injure the structures or connections in the brain that control these functions. We refer to these disorders as “aphasia”.

In this article we will describe the main symptoms and most frequent causes of Wernicke’s aphasia , which is characterized by a pronounced deficit in language comprehension and other problems associated with it.

What are aphasias?

Aphasias are language disorders that occur as a result of injuries to the brain. Depending on the regions and neural pathways that are affected, very different signs can appear, which gives rise to the different types of aphasia.

In many cases, however, the deficits combine distinct alterations or are widespread. When the latter occurs, usually as a result of massive damage to the left hemisphere of the brain, we speak of global or total aphasia.

Some of the basic criteria used to classify aphasias are the degree of verbal fluency, the quality of phoneme articulation, the ability to understand and repeat words pronounced by others, the correction of syntax and the presence of unintended or incorrect phonemes.

Since the structures in the brain that control the production and understanding of speech correspond to the areas responsible for reading and writing, deficits in aphasia appear not 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 difficulties in understanding language , which in turn leads to an inability to repeat the words of other people; this criterion is very relevant in the neuropsychological assessment of aphasias.

In contrast, and unlike other aphasias (in particular Broca’s), Wernicke’s speech remains fluent – in fact, in many cases it becomes excessively fluent. However, frequent errors occur and patients are often not aware of them.

According to Aleksandr Luria, who calls this disorder “acoustic-agnostic aphasia”, the key problem of Wernicke’s aphasia is found in the analysis and synthesis of phonemes during the process of speech perception ; the deficit is due to lesions in the secondary areas of language, which control these functions.

This type of aphasia is also known as “receptive”, “sensory”, “understanding”, “acoustic”, “syntactic” and “central” aphasia . These qualifiers 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 that usually occurs as a result of chronic alcoholism or other factors that cause a deficit of thiamine (vitamin B1), such as malnutrition.

Symptoms and main characteristics

Wernicke’s aphasia can be identified primarily from the affected person’s speech. Although Wernicke’s aphasia has normal rhythm, fluency and prosody , it is characterised by frequent repetition, errors and the inclusion of nonsense words and phrases.

The most characteristic symptoms and features of Wernicke’s aphasia are associated with receptive deficits, which prevent proper language processing. Among the main clinical features of this disorder are the following:

  • Severe deficit in listening and reading comprehension of language .
  • Inability to repeat words and phrases correctly.
  • Difficulties in remembering or pronouncing names of objects and living beings (anomie)
  • Maintenance or excess of speech and writing fluency
  • Absence of alterations in the articulation of phonemes.
  • Substitution of words by others with a similar meaning (semantic paraphrases).
  • Use of words without meaning (neologisms).
  • Speech and writing are incomprehensible and inconsistent because of the so-called “word salad”.
  • Lack of awareness of linguistic errors (anosognosia).

Causes of this disorder

Aphasias are normally produced as a consequence of cerebrovascular accidents , although any other type of factor that causes damage in certain regions of the brain is likely to cause aphasia: head trauma, brain tumours, neurodegenerative disorders, viral infections…

In the case of Wernicke’s aphasia, the lesions are located at the back of the upper twist of the left temporal lobe . Previously this disorder was specifically associated with damage to the first upper left temporal gyrus, which corresponds to area 22 of the classification made by Brodmann or “Wernicke’s area”.

Damage in this section of the temporal upper gyrus not only affects the frontal lobe regions directly involved in language, but also isolates them from most of the temporal, parietal and occipital lobes.