Being able to speak, to listen, to read and to write are things that most people readily take for granted. As a result of injuries to certain areas of the brain, any or all of these capacities can be impaired. This is referred to as aphasia. These impairments can range from relatively mild deficits to almost total loss of language skills.
Types of Aphasia – While there are many different classifications of aphasia, the most commonly described are as follows:
- Expressive Aphasia – In this type of aphasia (also known as Broca’s aphasia), the person has difficulty using spoken language, at either the level of individual words or sentences. In severe cases speech may consist of an interrupted series of individual words. This does not mean simply delays between the correctly ordered words in a sentence, but a collection of words spoken in a seemingly random, interrupted fashion.
- Receptive Aphasia – In receptive aphasia (also known as Wernicke’s aphasia), it is the comprehension of language spoken by others that is affected. This may mean radically slowed, or even absent comprehension. Figures of speech may be completely misunderstood or taken for the literal meaning. For example, “Wow, you guys really worked your butts off!”
- Global Aphasia – For someone with global aphasia, both using words and understanding them can be impaired. This can lead to a near total lack of communication.
The range of severity of aphasias can vary dramatically, and the ability of the affected person themselves to comprehend their difficulty depends upon the type of aphasia that they have. For someone with expressive aphasia, they actually comprehend, and hear, that they have altered speech patterns. In some cases, aphasia may appear as an inability to name objects and the patient will use non-specific naming words and phrases to describe items such as “thing” and “you know” and “what-cha-ma-call-it”.
What Causes Aphasia?
The brain processes language in different areas but for most people the majority of speech and language processing occurs in the left cerebral hemisphere. For some left handed people language processing may occur in the right hemisphere. For expressive aphasia the damage commonly occurs in a region nearer to the front of the brain in an area known as the inferior frontal gyrus. For receptive aphasia, the damage often is found to have occurred in or near the posterior regions of the superior temporal gyrus of the brain.
Recent studies using techniques such as functional magnetic resonance imaging (fMRI) have begun to show that the language areas of the brain actually may not localize to exactly the same spot in different people. These results help to explain why, for example, apparently very similar damage in different people caused by a stroke can have profoundly different effects on language skills.
To learn more about aphasias visit the National Aphasia Association and the American Speech-Language-Hearing Association.
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