Types of Aphasia
Broca's aphasia (expressive aphasia)
Expressive aphasia, known as Broca's aphasia in clinical neuropsychology and agrammatic aphasia in cognitive neuropsychology, is an aphasia caused by damage to anterior regions of the brain, including (but not limited to) the left inferior frontal region known as Broca's area
Sufferers of this form of aphasia exhibit the common problem of agrammatism. For them, speech is difficult to initiate, non-fluent, labored, and halting. Intonation and stress patterns are deficient. Language is reduced to disjointed words and sentence construction is poor, omitting function words and inflections (bound morphemes). A person with expressive aphasia might say "Son ... University ... Smart ... Boy ... Good ... Good ... "
For example, in the following passage, a Broca's aphasic patient is trying to explain how he came to the hospital for dental surgery:
- Yes... ah... Monday... er... Dad and Peter H... (his own name), and Dad.... er... hospital... and ah... Wednesday... Wednesday, nine o'clock... and oh... Thursday... ten o'clock, ah doctors... two... an' doctors... and er... teeth... yah.
In extreme cases, patients may be only able to produce a single word. The most famous case of this was Paul Broca's patient Leborgne, nicknamed "Tan", after the only syllable he could say. Even in such cases, over-learned and rote-learned speech patterns may be retained—for instance, some patients can count from one to ten, but cannot produce the same numbers in ordinary conversation.
Comprehension is usually preserved and patients who recover go on to say that they knew what they wanted to say but could not express themselves. Residual deficits will often be seen.
Expressive aphasia is also a classification of non-fluent aphasia, as opposed to fluent aphasia. Diagnosis is done on a case by case basis, as lesions often affect surrounding cortex and deficits are not well conserved between patients.
Wernicke's aphasia (receptive aphasia)
Receptive aphasia, also known as Wernicke's aphasia, fluent aphasia, or sensory aphasia in clinical neuropsychology and cognitive neuropsychology, is a type of aphasia often (but not always) caused by neurological damage to Wernicke's area in the brain (Brodman Area 22, in the posterior part of the superior temporal gyrus of the dominant hemisphere). This is not to be confused with Wernicke's encephalopathy or the Wernicke-Korsakoff syndrome. If Wernicke's area is damaged in the non-dominant hemisphere, the syndrome resulting will be sensory dysprosody - the lack of ability to perceive the pitch, rhythm, and emotional tone of speech.
Speech is preserved but language content is incorrect. This may vary from the insertion of a few incorrect or nonexistent words to a profuse outpouring of jargon. Rate, intonation and stress are normal. Substitutions of one word for another (e.g. "telephone" for "television") are common. Comprehension and repetition are poor.
- I called my mother on the television and did not understand the door. It was too breakfast, but they came from far to near. My mother is not too old for me to be young.
If excessive, this may be confused with the psychiatric signs of "pressure of speech" and "word salad".
Patients who recover from Wernicke's aphasia report that while aphasic they found the speech of others to be unintelligible, and even though they knew they were speaking, they could neither stop themselves nor understand what they had just said.
Nominal aphasia (anomic aphasia)
Nominal aphasia (also known as anomic aphasia) is a form of aphasia (loss of language capability caused by brain damage) in which the subject has difficulty remembering or recognizing names which the subject should know well. The subject speaks fluently, grammatically, has normal comprehension, and the only deficit is trouble with "word finding," that is, finding appropriate words for what they mean to say.
Subjects often use circumlocutions (speaking in a roundabout way) in order to express a certain word for which they cannot remember the name. Sometimes the subject can recall the name when given clues. Sufferers are often frustrated when they know they know the name, but cannot produce it.
"Hold on, I should know the name of that thing... Give me a minute ..."
Sometimes subjects may know what to do with an object, but still not be able to give a name to the object. For example, show a subject an orange, and ask what it's called. The same subject may be well aware that the object can be peeled and eaten, and may be able to demonstrate this by actions or even verbal responses. Whether such a subject could name the color of the orange is unknown.
Anomia is caused by damage to various parts of the parietal lobe or the temporal lobe of the brain. This type of phenomenon can be quite complex, and usually involves a breakdown in one or more pathways between regions in the brain. The responses may also differ depending on whether objects are shown in the right or left hand side of the visual field.
"Averbia" is a specific type of anomia in which the subject has trouble remembering only verbs. This is caused by damage to the frontal cortex, in or near Broca's area.
Another type of anomia is "color anomia", where the patient can distinguish between colors but cannot identify them by name
The symptoms of global aphasia are those of severe Broca's aphasia and Wernicke's aphasia combined. There is an almost total reduction of all aspects of spoken and written language, in expression as well as comprehension. Improvement may occur in one or both areas (expressive and receptive) over time with rehabilitation. What is interesting to point out is that in patients of global aphasia other cognitive skills remain functioning - a phenomenon affirming that language faculty is indeed a separate domain.
Global aphasia is a type of aphasia that is usually associated with a large lesion in the persylvian area. It involves a "left side blowout" which includes Broca's, Wernicke's and the Arcuate Fasiculus.
When injury initially occurs to all of these areas the progression starts out with Global aphasia in the first 1-2 days, because of brain swelling. From there it evolves into Brocas or Wernicke's for 1-3 months (usually Broca's) then it resolves into a presidual anomic aphasia. Studies show that spontaneous improvement, if it happens, happens by six months, but no one comes back 100%.
Persons with global aphasia are usually mute or use repetitive vocalization. The person can sometimes use simple words, such as expletives, repetitevly. They are marked by a severe impairment of both understanding and expression of language.
Conduction aphasia, also called associative aphasia, is a relatively rare form of aphasia, caused by damage to the nerve fibres in the arcuate fasciculus, which connects Wernicke's and Broca's areas.
Patients with conduction aphasia show the following characteristics:
- speech is fluent
- comprehension remains good
- oral reading is poor
- repetition is poor
- transpositions of sounds within a word ("television" → "velitision") are common.
To understand the symptoms, recall that Broca's area is associated roughly with expression, Wernicke's area with comprehension.
With both areas intact but the neural connections between them broken, there is the curious condition where the patient can understand what is being said but cannot repeat it (or repeats it incorrectly). This patient will also end up saying something inappropriate or wrong, realize his/her mistake, but continue making further mistakes while trying to correct it.
Transcortical motor aphasia
Transcortical Motor Aphasia (TMA) results from an injury to the anterior superior frontal lobe. The injury is typically caused by a cerebrovascular accident (CVA), commonly referred to as a stroke. The area of insult is sometimes referred to as a watershed region, a region surrounding Broca's area. The insult typically involves the left hemisphere as most people (regardless of handedness) are left hemisphere dominant for language (nearly 100% of left-handers, about 85% of right-handers).
People with TMA generally have good comprehension since Wernicke's area is usually not affected. People with TMA experience non-fluent (halting and effortful) speech due to frontal lobe damage and their utterances are typically only one or two words long. People with TMA retain the ability to repeat words, phrases or sentences. Repetition is preserved since the arcuate fasciculus (the neural pathway that connects Wernicke’s and Broca’s areas via the parietal lobe) is intact. Preserved repetition is a defining quality of all transcortical aphasias. People who suffer from transcortical motor aphasia, however, may experience delays in initiation when they try to repeat words due to damage in the frontal lobe.
As writing ability parallels speaking ability, it follows that people who suffer from TMA have severely impaired writing ability. As writing is a secondary modality (learned through formal instruction in grade school) it is always more severely affected than a primary modality like speaking.
Transcortical sensory aphasia
Transcortical Sensory Aphasia, or TSA, is a type of Aphasia where sufferers have poor comprehension, but have fluent, grammatical speech. Patients can communicate well and are capable of good repetition. The main problem lies within the brain in a region known as the Temporal-occipital-parietal junction, located behind Wernicke's area. This disruption causes TSA sufferers to have Semantic paraphasia wherein aphasics do not use the correct word, but use another word of similar content (ie. Apple is mistaken for Orange, Paper is mistaken for Pencil, etc.)
Mixed transcortical aphasia
Mixed transcortical aphasia is the least common of the three transcortical aphasias (behind transcortical motor aphasia and transcortical sensory aphasia, respectively). Mixed transcortical aphasia is characterized by severe speaking and comprehension impairment, but with preserved repetition. People who suffer mixed transcortical aphasia struggle greatly to produce propositional language or to understand what is being said to them, yet they can repeat long, complex utterances or finish a song once they hear the first part.
In this rare type of aphasia, Broca's area, Wernicke's area, and the arcuate fasciculus are intact but the watershed region around them is damaged. This damage isolates these areas from the rest of the brain. The most frequent etiology of mixed transcortical aphasia is stenosis (narrowing) of the internal carotid artery.
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It uses material from the Wikipedia article "Metasyntactic variable".