The Neuroscience on the Web Series:
CMSD 636 Neuropathologies of Language and Cognition

CSU, Chico, Patrick McCaffrey, Ph. D.


Chapter 8. Specific Syndromes: The Fluent Aphasias


Fluent Aphasias

Wernicke's Aphasia

This is the most common of the fluent aphasias. It is also known as semantic aphasia

Site of Lesion

The lesion is located in Wernicke's area, which is the posterior region of the left superior temporal gyrus or the first gyrus of the temporal lobe. Brodmann's areas 21 and 42 correspond to Wernicke's area (FitzGerald, 1997). The damage often extends into the parietal lobe, affecting the angular gyrus (Brodmann's area 39). Meaning is associated with speech sounds in Wernicke's area. It is also a center for abilities like reading and writing which have been learned in conjunction with auditory comprehension. As Wernicke's area is adjacent to Heschl's gyrus, it can be considered an auditory association area. Temporal lobe lesions are responsible for a number of problems other than aphasia.

Characteristics

The major impairment is semantic. With severe Wernicke's aphasia there is usually a severe impairment in auditory comprehension. Speech, while fluent, is semantically inappropriate and paraphasic. The speech of Wernicke's patients is sometime called cocktail hour speech. Comprehension and expression tend to be equally impaired. Patients with moderate Wernicke's can get the point in conversations but miss many specifics (Brookshire, 1997).

Articulation is normal

Melodic Line is unaffected. If one ignores the content, the form of the patient's speech may sound normal. They have long, grammatically well formed utterances that contain almost no meaning.

According to Goodglass and Kaplan, 1983, speech is paragrammatical. Wernicke's patients make grammatical errors but their speech cannot be considered agrammatical as it does contain complex syntactical forms.

Wernicke's aphasics can exhibit disassociation between the sounds or sights of words and their meanings (Brookshire, 1997).

Although the form of language may be relatively unimpaired, speech may be essentially meaningless in the most severe cases, and sound a little like "Jabberwocky."

Verbal paraphasias consist of words usually of allied meanings: knife for fork. Literal or phonemic paraphasias consist of made up but similar sounding syllables (bife for knife) with fifty percent or more correct). Neologistic paraphasias are when less than half of the utterance is correct (bort for fork). Paraphasias are common (FitzGerald, 1997).

Repetition is typically poor. Patients may use paraphasias and also commonly add words, complicating the utterance. This phenomenon is known as augmentation. Also due to auditory comprehension deficits, the patient may repeat the examiner's words without understanding them.

Word finding problems are very common.

Confrontation naming is typically impaired.

Auditory comprehension is impaired. In severe cases, patients may not even understand one word utterances.

Both reading and writing can be seriously impaired if the angular gyrus is compromised.

Hemiplegia/hemiparesis are rare due to the posterior nature of the lesion. Patients can usually still use their right hands to write and the form of their handwriting may be normal. However, the content of their written output is very similar to their speech.

A phenomenon called press of speech also characterizes Wernicke's aphasics. Patients may speak very rapidly, interrupting others. It may seem as though the patient is striving for a sense of closure or a sense that he has actually communicated what he intended to say (Goodglass and Kaplan, 1983).

Unlike Broca's aphasics, Wernicke's aphasics tend to have anosognosia (lack of awareness) of their communication problems (Davis, 1983). They often seem unaware of their speech problems. Or, at least, they are not concerned about them. (The occasional patient will be frustrated.) This lack of concern is indicative of the more severe cognitive problems that give Wernicke's patients a worse prognosis than Broca's.

Anomic Aphasia (also called amnesic)

Site of Lesion

According to Goodglass and Kaplan (1983), anomia can be localized with the least reliability of any of the aphasic syndromes. The lesion is often temporal parietal area. The angular gyrus may also be affected, causing alexia and agraphia. (Some patients with anomic aphasia can write well, however).

Characteristics

The boundary between anomic aphasia and Wernicke's aphasia is fuzzy, but classic cases of each syndrome can be readily distinguished from one another. A patient may initially be diagnosed with Wernicke's aphasia, but eventually come to resemble the profile of anomic aphasia as he/she recovers.

Naming or word finding problems are the major feature of the syndrome. Patients sometimes use elaborate circumlocutions to compensate for this, and the content of their speech may come to sound fairly bizarre as a result. For example, a patient might say that he's "had one of them up there" when trying to explain that he's had brain surgery.

Grammar is unaffected.

Paraphasias are rare.

Repetition is good.

Auditory comprehension is relatively intact.

Reading and writing are variable with abilities ranging from normal to very poor. Sometimes, a patient will be able to write a word that he cannot say, suggesting that its written and auditory representations were stored separately.

Anomia is typically the first language symptom of a brain tumor, even if the growth is located far away from the language center. It is also seen in a variety of dementias.

On the BDAE (Goodglass and Kaplan, 1983), anomic patients rarely receive extremely low scores. They typically have a severity rating of 3 or 4 (1 being very poor and 5 being relatively intact).

Conduction Aphasia

According to Bhatnager, and Andy (1995), conduction aphasia occurs in fewer than 10% of aphasia cases.

Site of Lesion

According to Geschwind, conduction aphasia results from damage to the arcuate fasciculus, a bundle of nerve fibers that lies below the supramarginal gyrus in the temporal lobe and connects Broca's and Wernicke's areas. Both Broca's and Wernicke's areas are left intact.

Lesions are also found in the left perisylvian area of the cortex.

Effected areas may include superior temporal gyrus, the insula (Island of Reil), the primary auditory cortex (Brodmann's areas 41 and 42), auditory association areas (Brodmann's 21 and 22), and the supramarginal gyrus (Brodmann's area 40).

Characteristics

Spontaneous speech is usually fluent. There are frequent literal paraphasias and error awareness, with attempts made by the patient to correct them (Bhatnager and Andy, 1995). In addition there can be some verbal paraphasias. Auditory comprehension and reading comprehension are fairly good.

Poor repetition, in comparison to problems with comprehension and spontaneous expression, is the hallmark of this syndrome. Spontaneous speech is better than repetition. Patients typically produce many paraphasias when trying to repeat. They may be able to reproduce short utterances, however, they will be unable to repeat polysyllabic words or syntactically complex utterances. Patients with this syndrome have difficulty repeating even the high probability sentences included in the repetition subtest of the Boston. Patients' ability to repeat numbers is typically much better than their ability to repeat words. Errors in number repetition tend to be verbal paraphasias while errors made while repeating words are typically literal (phonological) paraphasias When testing it's best to use sentences that contain both words and numbers for repetition tasks. For example the patient might be asked to repeat the sentence "There were 25 at the concert last week" (Goodglass and Kaplan, 1983).

Conduction aphasics usually perform even more poorly on tasks when given a model. (A Broca's patient would perform better when modeling.)

Although this is classified as a fluent aphasia, fluent speech may be restricted to brief runs (they don't sound like Wernicke's patients). In this case, conduction aphasics can be differentiated from Broca's aphasics by their good articulation, normal intonation and use of a variety of syntactic patterns.

The major speech difficulty in this syndrome is the sequencing of phonemes. Patients may produce many literal paraphasias. (This is another attribute that may cause confusion with Broca's aphasia.) The patient is aware of his paraphasic errors and will produce repeated approximations of the intended word, as if he is trying to untangle it. This phenomenon is called conduit d'approche (Goodglass and Kaplan, 1983).

Patients may distort words by adding syllables or by adding sounds to a word which are called intrusive additions.

Anomia is common.

Auditory Comprehension is typically nearly normal and may be completely intact. Conduction aphasics could comprehend the nouns and verbs in a sentence, but would not be able to understand grammatical morphemes such as prepositions and conjunctions because incoming information is not transferred from Wernicke's area to Broca's area.

A patient could understand "Do you write with a pen?"

A patient could not understand "Before you raise your hand, read this."

Unambiguous cases of conduction aphasia usually receive a score between 2 and 4 on the severity rating scale of the Boston. In very severe cases, the patient may receive a rating of 1 or 2 and it will be extremely difficult to differentiate the disorder from Broca's aphasia. When the patient is very fluent, the prevalence of paraphasias in his speech may result in a diagnosis of Wernicke's aphasia (Goodglass and Kaplan, 1983).

Reading abilities are commensurate with the patient's severity rating, but are typically good. They have difficulty reading aloud.

Writing typically contains spelling errors and transpositions of words and syllables (Brookshire, 1997).

Transcortical Sensory Aphasia

This is an extremely rare form of fluent aphasia.

Site of Lesion

It is hypothesized that this type of aphasia occurs when Broca's area, Wernicke's area and the arcuate fasciculus are undamaged but are cut off from the rest of the brain by infarcted tissue. A lesion of this type could occur due to vascular insufficiency because of problems at the ends of the cerebral arteries distribution system, the watershed areas of the blood supply.

Such lesions would be found in Brodmann's areas: 37, 22, and 39. Lesions in area 37 are known to cause anomia. Area 22 is near Wernicke's area and area 39 is the angular gyrus.

Characteristics

According to Goodglass and Kaplan (1983) the hallmark of this syndrome is extremely well-preserved repetition abilities in the context of no comprehension and no propositional speech. This shows that the arcuate fasciculus is still intact, allowing information to pass from Wernicke's to Broca's area. Patients can repeat very long, complicated utterances. Also, automatic speech is very good and they can produce lengthy chunks of memorized material like prayers and song lyrics if they can be made to understand the task.

In addition, patients may echo their conversation partners in such a way that they sound as if they do understand language and are participating in the conversation. For example, if asked if he likes his lunch, the patient might say "like lunch." Within the repeated phrases, phonology and intonation are intact.

Reading and Writing

Patients cannot read and also cannot write, even in the absence of paralysis or limb apraxia.

Auditory comprehension is non-existent. In the absence of other lesions, the patient would still be able to think, but would not be able to connect language with information about meaning stored in memory.

My experience with one patient revealed intact cognition, including his ability to find his way around the hospital. Prior to being assessed by me he had been diagnosed as having Wernicke's aphasia.

Such a patient would typically receive a score of 1 or 2 on the severity rating scale of Boston (1 is very low, 5 is relatively intact). A high repetition score is the only factor that would differentiate a transcortical sensory aphasia from Wernicke's and, in fact, patients are often misdiagnosed as having Wernicke's aphasia.

Other Aphasias

There are several syndromes of aphasia, which are considered to be neither fluent nor nonfluent.

Global Aphasia

This is the third most common aphasic syndrome after Broca's and Wernicke's.

Site of Lesion

This type of aphasia occurs when there are both anterior and posterior lesions.

Characteristics

All aspects of language are so severely impaired that there is no longer a distinctive pattern of preserved vs. impaired components. Articulation may be adequate in the context of stereotypical utterances. Prognosis is poor.

Mixed Nonfluent Aphasia

This diagnosis is given to patients who produce language that is similar to the telegraphic speech characteristic of Broca's aphasia, but cannot be categorized as actually having Broca's aphasia due to the severity of their auditory comprehension deficits.

Subcortical Aphasia

Lesions in the anterior subcortical area involving the limb of the internal capsule and putamen are associated with sparse language output and impaired articulation. Posterior subcortical lesions are associated with fluent forms of aphasia, while lesions of the thalamus may cause a global aphasia.


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