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

CSU, Chico, Patrick McCaffrey, Ph.D.


Chapter 7. Specific Syndromes: The Nonfluent Aphasias


Broca's Aphasia

This is the most common of the nonfluent aphasias. In older literature, it is called verbal aphasia (Head, 1926), motor aphasia (Goldstein, 1933), and efferent motor aphasia (Luria, 1964) . It is named after Paul Broca (1865), a French physician. According to FitzGerald,1996, the principal output from Broca's area is to cell columns in the tongue and face areas of the precentral gyrus.

Site of Lesion

The lesion that causes Broca's aphasia affects the third frontal convolution (both the gyrus and the sulcus) of the left frontal lobe. This location is called Broca's area. It corresponds to Brodmann's areas 44 and 45. According to Brookshire (1997) it makes up the lower part of the pre-motor cortex. The damage often extends down into the white matter and, in some cases, extends posteriorly to the most inferior part of the motor strip (Goodglass and Kaplan (2001).

Characteristics

Speech is telegraphic, meaning that articles, conjunctions, prepositions, auxiliary verbs and pronouns (function words) and morphological inflections (e.g. plurals, past tense), are omitted. In addition, nouns, verbs, adjectives and adverbs (content words) may be retained. Output can be restricted to noun-verb combinations. There is often a concomitant apraxia of speech (AOS).

Sentence length is short. Average utterance length (MLU) is typically about 2. In extreme cases, the patient may only be able to produce single word utterances.

Syntax and morphology are affected; only the most basic and over-learned grammatical forms are produced (often limited to nouns and verbs).

Speech is labored and slow.

Melodic Contour is flat.

Articulatory Agility is impaired. Potential problems include:

Simplification of consonant clusters (e.g. t/st, p/spl).

Distortion of consonants.

Substitutions are infrequent.

A few paraphasias may occur. They will usually be literal.

Repetition is typically impaired, falling at about the middle of the Boston Diagnostic Aphasia Examination (BDAE) scale. (Repetition and spontaneous speech are impaired to about the same degree in Broca's aphasia.)

Word finding is impaired.

In Broca's aphasia auditory comprehension appears superior to expressive language, and usually falls within the 50th-90th percentile range on the Boston (McCaffrey, 2005). The patient's ability to understand grammer will be affected. So, while it can be said that auditory comprehension is good in comparison with expression, it is not normal. The knowledge of linguistic rules will be the same, but expression may be apraxic as well as aphasic.

In our clinic a Broca's aphasic patient when asked what his favourite food was he said: "Uh...uh...uh....choc...like...chocolate."

Note: I have frequently used the Token Test (DeRenzi & Vignolo, 1966), which assesses subtle receptive language dysfunction, to evaluate the auditory comprehension of Broca's aphasics and to differentiate between Broca's aphasia and apraxia of speech AOS. when the patient does well you know that s/he doesn't have aphasia. When s/he does poorly it is more difficult to make a diagnosis. The test which is also normed for children, has five parts involving the manipulation of objects of different colors, shapes, and sizes, and becomes progressively more difficult. It tests receptive language by requiring the patient to follow instructions like "Put the red square on the yellow circle." However you must be aware that words like "before" which are grammatical morphemes may be missed due to conceptual or semantic problems. Also, limb apraxia or colour blindness may not allow the patient to carry out the instructions, even though s/he understands them.

Hemiplegia/Hemiparesis of the right side is common (remember, the language center is in the left hemisphere for more than 90% of the population) The face and arm are most likely to be affected due to the organization of the motor strip.

Apraxia frequently accompanies this type of aphasia as it is likely caused by lesions to area 44/45. This poorly articulated speech shows up most frequently in longer words and phrases.

Broca's aphasics typically have low frustration tolerance. They are aware of their errors and may respond to them with a catastrophic reaction which might include weeping.

Broca's aphasics may receive a rating of 1 or 2 on the BDAE, especially soon after their strokes, due to the scarcity of their speech output. As they recover, they may be rated as 3, 4 or 5 (Goodglass and Kaplan, 1983).

Typically there is better recovery of language function in Broca's than in any of the other aphasia syndromes.

 

Transcortical Motor Aphasia

 

Site of Lesion

Lesions are typically smaller than those that cause Broca's aphasia and are superior to and often anterior to Broca's area. Broca's area itself is not affected, but the damage may extend down into the white matter including the white matter below Broca's area. Luria (1966) referred to this syndrome as dynamic aphasia.

Communication between Broca's area and the pre-motor or supplementary motor area (Brodmann's Area 6) is cut off. Because Wernicke's area and the arcuate fasciculus are spared, these patients have good repetition (Brookshire, 1997). This type of lesion may also sever links between Broca's area and the basal ganglia and/or the thalamus. There are motor areas in the thalamus and the basal ganglia that may have some kind of pre-motor function also. In addition, the damage could cause symptoms by affecting the link between Broca's area and the limbic system which also seems to be involved in memory (hippocampus) and speech and language.

Characteristics

Repetition is much better than other types of speech. In repetition, grammar and articulation are normal.

The patient will have great difficulty initiating and organizing responses in conversation, but will be unable to answer highly structured questions. For example someone with transcortical aphasia would probably not be able to answer question like "Why are you in the hospital?" but would be able to name their home town, answer yes/no questions, and name the days of the week. When faced with a question he/she cannot answer, the patient may appear "blocked" and produce fragmentary responses. Generally, with transcortical motor aphasia there is little or no paraphasia, fair to good articulation and fair to excellent auditory comprehension (Goodglass and Kaplan, 1983).

Articulation in general is fair to good.

Little or no paraphasia is present.

Confrontational naming is well-preserved. The patient will respond well to prompting with phonemic cues.

Auditory comprehension is fair to excellent.

According to Goodglass and Kaplan (2001) the fluent/nonfluent distinction is not especially applicable to this syndrome. Sometimes the patient will produce a grammatically correct, well-articulated sentence.


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