Symptoms And Classification A The Nature of Communication Behavior

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When an individual generates an idea that he or she wants to verbalize, certain physiologic and acoustic events must take place in order for it to be transformed into words and sentences. The message is converted into linguistic form at the listener's end. The listener, in turn, fits the auditory information into a sequence of words and sentences that are ultimately understood. The system of symbols that are strung together into sentences expressing our thoughts and the understanding of those messages is referred to as language.

Language is made up of phonology, the system of speech sounds that are combined to form the syllables that comprise words; a lexical system, or vocabulary of words, used to communicate information; the grammar, or syntax, that determines the sequence of words that are acceptable as utterances; and semantics, or the meaning system. When communicating using speech, we also employ stress and intonation, referred to as prosody, to help make distinctions among questions, statements, expressions of emotions, shock, exclamation, and so forth.

Broca Aphasia Pantommime

Figure 1 Lateral view of the left hemisphere of a normal adult brain using thin contiguous MR slices and Brainvox. Brodmann's areas 44 and 45 correspond to the classic Broca's area, and area 22 to Wernicke's area. Areas 41 and 42 correspond to the primary auditory cortex; these are located in the depth of the sylvian fissure and cannot be seen in a lateral view of the brain. Area 40 is the supramarginal gyrus; area 39 is the angular gyrus. Area 37, principally located in the posterior sector of the second and third temporal gyrus, does not have correspondence in gyral nomenclature. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 45. Academic Press, San Diego.]

Figure 1 Lateral view of the left hemisphere of a normal adult brain using thin contiguous MR slices and Brainvox. Brodmann's areas 44 and 45 correspond to the classic Broca's area, and area 22 to Wernicke's area. Areas 41 and 42 correspond to the primary auditory cortex; these are located in the depth of the sylvian fissure and cannot be seen in a lateral view of the brain. Area 40 is the supramarginal gyrus; area 39 is the angular gyrus. Area 37, principally located in the posterior sector of the second and third temporal gyrus, does not have correspondence in gyral nomenclature. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 45. Academic Press, San Diego.]

B. Types of Aphasia

Aphasia is generally of sudden onset and is sometimes present during the acute phase of an illness and then disappears in a matter of hours or days. In this context, the term aphasia is used when its symptoms persist for more than 1 month.

An exception to the typically sudden onset of aphasia occurs in primary progressive aphasia (PPA), a diagnosis that is being made with increasing frequency. PPA is usually gradual in onset, sometimes emerging over a period of years, and may evolve into a dementia or Alzheimer's disease.

Individuals with aphasia may show evidence of impairment in any or all language systems ranging from a virtually total inability to communicate using the speech code, but with preserved ability to communicate through the use of gestures, facial expression, and pantomime, to a mild, barely perceptible language impairment.

There is a group of distinct aphasia syndromes that have a high correlation with the location of anatomical lesions. However, it is not always possible to classify patients according to these syndromes. In fact, estimates of the proportion of cases that can be unambiguously classified range from 30 to 80%.

The determination of the aphasia syndrome that best fits depends primarily on identification of the characteristics of speech production combined with a judgment of fluency. Speech output that is hesitant, awkward, interrupted, and produced with effort is referred to as nonfluent aphasia, in contrast to speech produced with ease of articulation, at a normal rate, with preserved flow and melody but that may be lacking in coherence, which is referred to as fluent aphasia. Fluencyjudgments are generally derived from an extended conversation with a patient.

1. Fluent Aphasia

Fluent aphasia is characterized by fluent speech produced at a normal rate and melody, accompanied by impaired auditory comprehension. It is generally associated with a lesion in the vicinity of the posterior portion of the first temporal gyrus of the left hemisphere. When fluent aphasia is severe, the individual may substitute sounds and words with such frequency and magnitude that speech may be rendered meaningless. Some produce nonsense words, referred to as neologisms or jargon aphasia. Those with fluent aphasia tend to have greatest difficulty retrieving the substantive parts of speech (i.e., nouns and verbs) and also tend to manifest impaired awareness. They do not generally evidence paralysis or weakness of the right arm and leg.

a. Wernicke's Aphasia The most common variety of fluent aphasia is Wernicke's aphasia, characterized by fluently articulated speech sometimes marked by word substitutions and accompanied by impaired auditory comprehension. Individuals with Wernicke's aphasia may produce what appear to be complete utterances, use complex verb forms, and speak at a rate greater than normal that is sometimes referred to as press of speech. Their communication behavior, profile of language impairment, and lack of physical impairment may lead to a psychiatric diagnosis

b. Conduction Aphasia Conduction aphasia is also one of the fluent aphasias, but unlike Wernicke's aphasia, auditory comprehension is generally more intact. A deficit of word and sentence repetition prevails and is marked by phonemic paraphasic errors—that is, the production of inappropriate, although precisely articulated speech sounds.

c. Transcortical Sensory Aphasia Individuals with transcortical sensory aphasia have fluent speech output marked by substitutions of words and severe impairment of aural comprehension. Transcortical sensory aphasia is distinguishable from Wernicke's aphasia by a preserved repetition performance. Also, those with transcortical sensory aphasia often "echo" questions, a behavior referred to as "echolalia."

d. Anomic Aphasia The primary characteristic of anomic aphasia is a pervasive difficulty in word retrieval in the presence of fluent, well-articulated, and grammatically correct output and intact auditory comprehension. Anomic aphasia is often the mildest form of aphasia and is sometimes the recovery end point of other types of aphasia. It may also characterize the early stages of primary progressive aphasia.

2. Nonfluent Aphasia

Nonfluent aphasia is characterized by limited vocabulary, sometimes restricted to nouns, verbs, adverbs, and adjectives; slow, hesitant speech production, awkward articulation; and a restricted use of grammar with normal or near-normal auditory comprehension. Individuals with nonfluent aphasia are often referred to as agrammatic since they tend to have a pervasive

Damasio Brain Templates

Figure 2 Magnetic resonance template from a patient with Wernicke's aphasia (WG0988). The lesion involved the posterior sector of the left superior and middle temporal gyri but did not extend into the parietal lobe. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 50. Academic Press, San Diego.]

Figure 2 Magnetic resonance template from a patient with Wernicke's aphasia (WG0988). The lesion involved the posterior sector of the left superior and middle temporal gyri but did not extend into the parietal lobe. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 50. Academic Press, San Diego.]

grammatical impairment as the result of difficulty in retrieving less substantive parts of speech (i.e., prepositions, articles, and pronouns).

Nonfluent aphasia is usually associated with a high degree of deficit awareness and impaired motor function on the right side of the body (hemiplegia-paresis). The intact deficit awareness generally present in nonfluent aphasia may produce a significant degree of frustration.

a. Broca's Aphasia The most common type of nonfluent aphasia is Broca's aphasia, which is characterized by awkward articulation, restricted vocabulary, and grammatical forms in the presence of normal or near-normal auditory comprehension. Writing performance generally mirrors speech production and reading may be less impaired than speech and writing. In the majority of individuals with Broca's aphasia, awareness of deficit is good and paralysis on the right side of the body (hemiplegia) is present (Fig. 3).

3. Apraxia of Speech

The term apraxia refers to an impairment in the ability to carry out physical movements in the absence of paralysis or sensory impairment to the body part. Apraxia of speech (AOS), a term synonymous with verbal apraxia and speech dyspraxia, is seldom manifest independent of Broca's aphasia, however mild. It is an articulatory deficit characterized by awkward and labored articulation, distortion of phoneme production, and sound substitutions in the absence of impaired strength or coordination of the motor speech system. Unlike individuals with dysarthria, an impairment of speech associated with pathology of the motor speech system, individuals with AOS do not have difficulty performing nonspeech movements of the oral musculature.

a. Transcortical Motor Aphasia This type of aphasia is characterized by nonfluent speech, intact repetition, impaired auditory comprehension, and a tendency to perseverate and substitute both sounds and words.

4. Global Aphasia

When aphasia is severe in all modes of communication, rendering a person markedly restricted in participating in verbal interactions, it is referred to as global aphasia. Individuals who manifest global aphasia are often able to produce serial or automatic speech (i.e., counting in series, reciting the days of the week, reciting prayers, singing the words to songs, and using common everyday greetings). Global aphasia is generally associated with extensive cerebral damage, often in both hemispheres.

Damasio Brain Templates

Figure 3 Computerized tomographic template from a patient with Broca's aphasia (MW0018). The lesion involved only the superior sector of Broca's area (area 44) and the premotor region (area 6) immediately above it. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 55. Academic Press, San Diego.]

Figure 3 Computerized tomographic template from a patient with Broca's aphasia (MW0018). The lesion involved only the superior sector of Broca's area (area 44) and the premotor region (area 6) immediately above it. [reproduced with permission from Damasio, H. (1998). Neuroanatomical Correlates of the Aphasias. In Acquired Aphasia, 3rd ed., (M. T. Sarno, ed.), p. 55. Academic Press, San Diego.]

5. Primary Progressive Aphasia

The onset of language impairment in primary progressive aphasia (PPA), unlike the classic aphasia syndromes, begins gradually. It is often associated with degenerative disease, such as spongiform encephalopathies and Pick's disease. Typically, the condition begins with the gradual onset of word retrieval difficulties, especially for nouns and/or verbs. Although individuals with PPA may appear to be free of cognitive deficits for some time, language deficits other than word-finding difficulties, especially the cognitive symptoms of dementia, usually begin to emerge over time.

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