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DISORDERS OF SPEECH AND LANGUAGE Aphasia or dysphasia Loss or impairment of the production or comprehension of spoken or written language because of an acquired lesion of the brain. Dysarthria and anarthria A defect in articulation with intact mental functions and comprehension of spoken and written language and normal syntax (grammatical construction of sentences). pure motor disorder of the muscles of articulation and may be a result of flaccid or spastic paralysis, rigidity, repetitive spasms (stuttering), or ataxia. Aphonia or dysphonia An alteration or loss of voice because of a disorder of the larynx or its innervation Articulation and language are unaffected APHASIA Alexia loss of the ability to read common accompaniment of aphasia caused by temporal or parietal lobe lesions. In most cases, accompanied by agraphia, the inability to write. Pure alexia without agraphia and with normal comprehension of spoken words From single lesion lateral to the occipital horn of the left lateral ventricle or combination of two lesions, one in the left occipital lobe and the other in the splenium of the corpus callosum. Such lesions sever connections between both visual cortices and the unilaterally located language areas Dyslexia incomplete alexia characterized by an inability to read more than a few lines with understanding. Developmental dyslexia is a common condition in children of normal intelligence who have difficulty learning to read. MRI examination reveals that some such children lack the usual anatomical asymmetry in the size of the planum temporale on the left and right sides. Expressive aphasia (Broca's aphasia), lesion in Broca's area of the frontal lobe, hesitant and distorted speech with relatively good comprehension. patient with Broca's aphasia can hear that he or she is talking nonsense patient with receptive aphasia talks fluently without being aware of the failure to produce meaningful words. Broca's Original Patient In April 1861 Broca encountered a patient named Leborgne who had a 20-year history of inability to produce meaningful words. He had been nicknamed "Tan" because "he could no longer produce but a single syllable, which he usually repeated twice in succession; Regardless of the question asked him, he always responded: tan, tan, combined with varied expressive gestures. This is why, throughout the hospital, he is known only by the name Tan." Leborgne died a week later and at autopsy was found to have long-standing damage to his left inferior frontal gyrus Although attention was focused on the cortical area that came to bear Broca's name, the damage was clearly more extensive, affecting additional cortical areas (including the insula) and parts of the basal ganglia Over the next 2 years, Broca investigated seven more cases of loss of spoken language. As in the case of Leborgne, all seven had left hemisphere damage. In an 1865 paper, Broca was one of the first to describe the idea of hemispheric dominance for language. This traditional model is appealingly simple and often successful in explaining a variety of aphasic disorders, but it is certainly an oversimplification. Functional imaging studies have shown increased blood flow in extensive networks of multiple cortical areas during most language tasks. In addition, not all aphasic patients have damage in the expected location. For example, damage restricted to Broca's area causes only a mild, temporary deficit in fluency; patients with severe, persistent Broca's aphasia always have more extensive damage that involves the insula and possibly the head of the caudate nucleus Similarly, patients with persistent Wernicke's aphasia typically have extensive lesions that include not just the superior temporal gyrus but also parts of the middle temporal gyrus and inferior parietal lobule. Finally, damage that includes the supramarginal gyrus is now thought to be the basis for conduction aphasia; a lesion of the arcuate fasciculus alone is insufficient Despite these complications, however, it is consistently found that within the cortical areas important for language, More anterior lesions result in greater deficits in the production of language, and more posterior lesions result in greater deficits in comprehension Receptive aphasia (Wernicke's aphasia), lesion in the receptive language area, notably in Wernicke's area. auditory and visual comprehension of language, naming of objects, and repetition of a sentence spoken by the examiner are all defective ISOLATION OF THE LANGUAGE AREAS (TRANSCORTICAL APHASIAS) The identifying feature of these language disturbances is a preservation of the ability to repeat. Destruction of the vascular border zones between anterior, middle, and posterior cerebral arteries may effectively isolate the intact motor and sensory language areas, all or in part, from the rest of the cortex of the same hemisphere. Transcortical aphasia of the receptive (or sensory) type Some patients cannot understand words and sentences or produce intelligible speech, but they can correctly repeat what the examiner says. associated with destruction of cortex in the middle temporal gyrus, inferior and posterior to Wernicke's receptive language area. Presumably, in transcortical sensory aphasia, as in Wernicke's aphasia, information cannot be transferred to the Wernicke area for conversion into verbal form. Transcortical aphasia of the expressive (or motor) type Cortical lesion anterior to Broca's expressive speech area. The impairment of spontaneous speech is similar to Broca's aphasia, but the patient can accurately repeat words or phrases spoken by someone else. Comprehension is relatively preserved occurs in two clinical contexts: (1) in a mild or partially recovered Broca's aphasia in which repetition remains superior to conversational speech (repeating and reading aloud are generally easier than self-generated speech) (2) with frontal lobe damage. Conduction aphasia Interruption of the arcuate fasciculus connecting Wernicke's and Broca's areas patient has poor repetition of a sentence spoken by the examiner but relatively good comprehension and spontaneous speech In other respects, the features of conduction aphasia resemble those of a mild Wernicke's aphasia. They share fluency and paraphasias in selfinitiated speech, in repeating what is heard, and in reading aloud; comprehension is by no means perfect, but compared with one who has Wernicke's aphasia, the patient with conduction aphasia has relatively little difficulty in understanding words that are heard or seen and is aware of his deficit. Global aphasia virtually complete loss of the ability to communicate after destruction of the cortex on both sides of the lateral sulcus. one of the consequences of occlusion of the left middle cerebral artery Main Aphasic Syndromes Type Broca's Speech Comprehension Repetition Localization Nonfluent, effortful, Relatively preserved agrammatical, paucity of output but transmits ideas Fluent, voluble, Greatly well articulated impaired but lacking meaning Impaired Frontal None Temporal, infrasylvian including angular and supramarginal gyri Conduction Fluent Relatively preserved None Supramarginal gyrus or insula Global Scant, nonfluent Very impaired None Large perisylvian or separate frontal and temporal Wernicke's Nonfluent and Fluent Aphasia The difference between nonfluent and fluent language production can be illustrated by transcriptions of the speech of two patients as they tried to describe a drawing of a picnic scene Patient MN was a right-handed, 62-yearold man who had a stroke in the anterior distribution of the left middle cerebral artery When tested at 2 years post stroke, his language profile was consistent with moderately severe Broca's aphasia. His spoken language was characterized by single-word utterances that contained articulation errors but was largely intelligible. His utterances were lacking grammatical structure, consisting primarily of nouns and a few verbs. When asked to describe the picnic scene, he said: "picnic … flying kite … swimming … house… tree … pouring water … boat … trees … okay … car." Patient JS was a right-handed, 65-year-old man who had a stroke in the posterior distribution of the left middle cerebral artery His initial diagnosis was conduction aphasia. At 3½ years post stroke, his speech was fluent, with a relatively normal sentence structure, but word-finding difficulties were evident. When describing the picnic scene, he said: "In the pier, somebody is fishing. Somebody is playing into the water. The man with the kite has the jeans with the pocket deal." His word-finding difficulties were more noticeable when he was asked to perform a naming task. For example, when trying to name a paper clip he said, "safety pin, no, the little clip." Anomic aphasia (isolation syndrome), Infarcts that isolate the sensory language area from surrounding parietal and temporal cortex characterized by fluent but circumlocutory speech caused by word-finding difficulties. Some authorities doubt the existence of anomic aphasia as a distinct clinical entity because most patients with lesions in the left parietal lobe have difficulty with naming Main Aphasic Syndromes Type of aphasia Transcortical motor Speech Comprehensio Repetition n Good Largely preserved Localization Transcortical sensory Fluent Impaired as Wernicke's Largely preserved Surrounding Wernicke area Pure word blindness (and alexia without agraphia) Anomic aphasia Normal but unable to read aloud Normal Normal Calcarine and white matter or callosum (or angular gyrus) Normal Deep temporal lobe Nonfluent Isolated Normal word- finding various sites difficulty Anterior or superior to Broca area