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

CSU, Chico, Patrick McCaffrey, Ph.D.


Chapter 6. Aphasia: Major Syndromes


The clustering of particular symptoms or language disturbances into syndromes is in part a function of the anatomic organization of the substrate for language in the brain. It is also that cerebral vascular accidents frequently affect certain vulnerable areas of the brain.These syndromes have been recognized for years, although there is some confusion about the classification scheme because terminology has been used inconsistently. Not all cases of aphasia fit the pattern of one of these syndromes. These syndromes simply represent the most frequently occurring clusters of language deficits. Depending on the rigor with which classification systems are applied, 30% to 80% of cases match up with a recognized sub-type of aphasia. Syndromes are representative of the most regularly recurring response patterns of language behavior to lesions in particular sites within the language zone. Differences in language performance may be due to the fact that lesions vary in exact location and extent, and because individuals may respond differently to the same lesion types and locations. Goodglass, Kaplan, and Barresi, 2001,

Mismatches occur because:

Exact site and extent of lesion vary.

Response to the same injury may differ from one individual to another.

Variations in the lateralization of language lead to corresponding differences in the anatomical organization of the components of language. Some adults develop aphasia from right hemisphere lesions, though they usually do not display paraphasic speech or have difficulties with auditory comprehension. The localization of language is the product of brain maturation and language use. Focal lesions in children may not cause the same clear-cut pattern of symptoms that would be seen in an adult. (Goodglass, Kaplan and Barresi, 2001)

Localizationists vs. Antilocalizationists

Pure localizationists believe that every type of linguistic behavior can be localized in a particular part of the brain. Pure antilocalizationists view the brain as an integrated unit like a hologram and believe that damage to one area of the brain will affect the functioning of the brain as a whole.

Some tests of aphasia are based on one of these perspectives. Boston Diagnostic Aphasia Examination is based in part on the principle of localization, assuming that identification of a particular syndrome of aphasia provides information about site of lesion. According to Kearns,1990, the use of CT and PET scans support the schema for localization.

Fluency vs. Nonfluency (Use Rating Scale of Speech Characteristics in the Boston)

This major subdivision of the aphasic syndromes is based on the characteristics of speech output (Goodglass and Kaplan, 1983). Fluent aphasia has normal articulation and rhythm of speech, but is deficient in meaning. McCaffrey, 2000. Nonfluent aphasic speech is slow and labored with short utterance length.

Nonfluent Aphasias Lesions are usually anterior to the fissure of Rolando.

Characteristics

The flow of speech is more or less impaired at the levels of speech initiation, the finding and sequencing of articulatory movements, and the production of grammatical sequences. Speech is choppy, interrupted, and awkwardly articulated. According to Goodglass et al, 2001 the speech of the nonfluent aphasic is laborious and there is usually less than three or four words in a breath group. Comprehension appears to be better than production and in a sense it is. The linguistic competence underlying both comprehension and production of language is the same, so both comprehension and production are affected by a nonfluent aphasia, McCaffrey, 2000. However, just as it is easier to understand a second language than to produce it, it is easier for the patient to understand what is said than to say it. One can often get by with only comprehending the key words and using non-verbal cues.

Site of Lesion

Nonfluent aphasias are the result of damage to the area of the brain anterior to the central fissure (Broca's area).

Fluent Aphasias

Characteristics

Phoneme selection and sequencing as well as syntax are preserved in fluent aphasia. Speech is characterized by a facility of articulation and many long runs of words combined using a variety of grammatical constructions. However, fluent speech is not equivalent to meaningful speech. Often the speech of fluent aphasics sounds like "jabberwocky." Typically, there are word-finding problems that most affect nouns and picturable action words. Comprehension is typically poor with fluent/posterior lesion aphasias. (Conduction aphasia would be the exception to this). The amount and type of paraphasias, the presence of auditory receptive impairments and of impaired repetition are variable in fluent aphasias, depending upon the exact site of lesion. According to Goodglass, Kaplan and Barresi, 2001, p. 7, "fluent aphasia is associated with easy articulation, facility with the patterns of sentence structure, but with difficulty in word finding and errors of word and sound substitution."

Site of Lesion

Fluent aphasias are the result of lesions affecting the post Rolandic area. Problems with meaning are associated with posterior lesions.


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Other courses in the Neuroscience on the Web series:
CMSD 620 Neuroanatomy | CMSD 342 Neuropathologies of Swallowing and Speech

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