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Language and Speech
Language is the usual “medium” for communication during mental status assessment. Like fundamental functions, the examiner must assess language early as disturbances can affect the rest of the examination. The first consideration is that language and speech are not the same. Language is the brain’s use of symbols for communication, and speech is the verbal motor expression of language. By this definition, language includes all symbolic communication whether spoken or written, sign language or Braille, or codes such as Morse Code or musical notation, and others. Speech, in contrast, is restricted to the verbal modality.To assess language, the examiner must divide language functions into their components. The most basic division is by spoken or written modality, hence this chapter is organized into Part 1 Spoken Language and Speech and Part 2 Written Language and Reading. Within these divisions, language testing includes encoding outgoing sequences of symbols (fluency, repetition, naming) and decoding incoming symbols (comprehension). Additional important aspects of the language examination focus on the association of language symbols with their meanings (semantics), prosody or the intonation of verbal output, the occurrence of paraphasic or word errors, and the evaluation of motor speech.The neural network subserving language function is a large system involving distributed regions and circuits. Despite their neuroanatomic impression, the classical modular centers and their disconnections remain useful for clinically characterizing language disorders if they are conceived as “hubs” of distributed neural networks. The classical model, known as the Wernicke-Lichtheim-Geschwind Model, focuses language functions around the perisylvian region of the left hemisphere ( Fig. 8.1 ). This model is anchored anteriorly in the Broca area in the inferior frontal region for production (fluency) and syntax (rules for combining words into clauses or phrases), and posteriorly in the Wernicke area in the superior temporal cortex for comprehension of phonemes (units of sound of a language) and facilitation of their semantic connections. Connections between the two travel along a dorsal, word sound or phonological circuit and along a ventral, word meaning or semantic circuit.
Part 1. Spoken Language and Speech
Aphasia (or “dysphasia”) is the loss or impairment of language caused by brain damage. With aphasia, there is a loss of ability to produce and/or understand written and/or spoken language. The aphasic syndromes are predominantly fluent versus nonfluent, which is a better dichotomy than “expressive” versus “receptive,” as all language impairments have an expressive component. The examiner further characterizes the aphasic syndromes in terms of the ability to comprehend, repeat, and name. These four characteristics—fluency, comprehension, repetition, naming—are the key to an aphasia examination, particularly for spoken language. Moreover, all those with aphasia have, to varying degrees, disturbances of reading and writing. In fact, disturbances in writing, in particular, is one way to assure the presence of an aphasia, rather than a primary speech problem.
Before describing the examinations there are some special issues to consider. First are differences depending on the hemispheric “dominance” of the individual. Left-hemisphere language dominance is present in strongly right-handed people, or approximately 90% of individuals. Those with left-handedness or a family history of left-handedness have less hemispheric specialization for language with more bilateral representation in the brain, particularly for more posterior language functions. Because of their greater bilaterality of language, compared with strong lateralized right-handers, left-handers who are language-impaired are less likely to fit into typical aphasia syndromes and more likely to have an initial aphasia with a better recovery. The incidence of true right-hemisphere “crossed-aphasia” in strongly lateralized right-handers is actually quite small. A further special consideration is the presence of bilingualism or multilingualism. Individuals who speak more than one language have different lexicons (vocabularies): “L1” for the first language, which is acquired directly from concepts, and “L2”, which is most commonly a later, sequentially learned language that may be acquired by translational equivalents from L1. Aphasic disorders in these patients may result in differential patterns or impairment and recovery, with L1 generally being the more robust.
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