Stroke - Aphasia: The nature of the condition
In this third article in the series on Aphasia, I would like to elaborate on the actual nature of the condition.
Aphasia is not a single disorder, but a series of communication breakdowns that stem from damage to the communication centers of the brain. In order to clarify the nature of aphasia, or dysphasia, it is necessary to look at basic neuroscience. The following diagram shows the left hemisphere of the brain, indicating areas important in language expression and auditory comprehension.
The language function is stored in the left side of the brain, particularly in the perisylvian area. This means that a left-sided stroke, especially in the frontal, temporal, and parietal lobes, will very likely have an effect on language. As the brain is very complex and has numerous interconnections, we may often see language difficulties arising from damage to other areas of the brain as well. Lesions of sub-cortical areas, such as the thalamus, as well as damage to the right hemisphere, may result in communication disorders.
The size and the site of the wound, as well as a number of factors relating to the age and general health of the stroke survivor also plays a role in whether there will be communication deficits. The patient’s level of communication fluency before the stroke can also play a role. The particular, individualised symptoms and manifestations of language deficits, will depend on the type of stroke.
These include ischaemic, haemorrhagic, or transient ischaemic attacks.
The following is a list of the most common symptoms:
- Problems with expression. Anomia, refers to the inability to find a particular word during a naming task, or during a conversation. This occurs in both aphasic and non-aphasic persons, and is familiar to all of us. In persons who are suffering from the effects of aphasia, it happens extremely frequently. â€¢ Paraphrasia, is making errors in the actual word produced.
- The word may sound like the 'target' word, or have some relationship to it - for example, a patient may say 'pork' for 'fork', or may call a fork a knife. Such slips of the tongue are not unusual, especially when we are tired, or not concentrating, but we see an exaggeration of this in a stroke survivor. Often, the patient is even unaware that he/she has made such errors. In the most severe type of paraphrasia, patients may actually create new words, called neologisms, or talk in a sort of jargon that only they can understand.
- Perseveration, where the patient seems to become stuck on, or persist in using one particular word or phrase, long after it is appropriate to do so.
- Stereotypes are common in more severe left-hemisphere strokes, where the only verbal utterances made, are well-worn phrases such as "hello," or even swear words, which occur in all communicative situations, even by patients who would never have dreamed of swearing before their stroke.
- A symptom commonly referred in aphasia is agrammatism. This is a telegram-like style in which the patient talks in short and ungrammatical sentences leaving out smaller words, such as articles (an, and, the, etc.), and prepositions (under, over, etc.). In the next issue I will be describing problems in auditory comprehension or receptive aphasia as it is also known.