Questions from Week 9 lecture –Exam content –Apraxia/Dyspraxia (disturbance/difficulty) –Apraxia Model –Differentiating Apraxia/Aphasia –Prosopagnosia

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Text of Questions from Week 9 lecture –Exam content –Apraxia/Dyspraxia (disturbance/difficulty)...

  • Slide 1
  • Questions from Week 9 lecture Exam content Apraxia/Dyspraxia (disturbance/difficulty) Apraxia Model Differentiating Apraxia/Aphasia Prosopagnosia vs. Variant of Prosopagnosia in Semantic dementia
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  • In most patients ideomotor apraxia is associated with left hemisphere (LH) lesions LH lesions destroy motor programs stored in inferior parietal lobe: Supramarginal or Angular Gyrus Or disconnect the flow of information from motor programs to premotor or motor areas necessary to initiate complex movement When asked to carry out a command with the right hand this pathway is used To carry out a command with the left hand, information must be carried to the right premotor cortex through Corpus Callosum and then conveyed to motor areas Unilateral (left) apraxia follow lesions located anterior Corpus Callosum
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  • Prosopagnosia vs Semantic dementia variant of Prosopagnosia Lesion: Bilateral occipital vs anterior right temporal Deficit: Faces not categorised as familiar (face recognition units function as a memory store); able to identify facial features; retains knowledge if given persons name vs progressive difficulty with face recognition/and or naming (semantic knowledge about person is lost)
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  • Aphasia
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  • Aphasia is defined as a loss or impairment of language function caused by brain damage (language content, comprehension, reading and writing) Aphasia/Dysphasia (disturbance/difficulty of language) used interchangeably Language is the complex symbolic signal system used by individuals to communicate with each other Language not only involves the content of speech but communication also occurs by reading and writing Language is intertwined into what it is to be human
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  • Language and Speech production: Speech Speech is the co-ordinated muscle activity required for oral communication Speech is the neural process involved in language Language is the content of speech Dysarthria Dysarthria is the impairment of the processes involved in speech production (tongue, throat, lips) May include subsystems of respiration, phonation, resonance, prosody (pauses, slow rate) and articulation Dysarthria and aphasia can coexist but one is often seen without the other
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  • Speech apraxia Disruption of motor program which determines the sequence of muscle contractions required to produce individual sounds and words (multisyllabic words e.g. caterpillar) Difficulty in speaking reflects a lesion that prevents execution (voluntary and on command) of the complex sequence of muscle contractions involved in speaking Manifests primarily as errors in articulation of speech and secondarily what are thought to represent compensatory alterations of prosody Prosody refers to the melody, pauses, intonation stresses/accents that enhance and liven speech Some consider speech apraxia to be a variant of Brocas aphasia rather than a disorder of speech
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  • Aphasia is a disorder of Language Dysarthria and Speech Apraxia are disorders of (the motor control) of Speech
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  • Aphasia results from a breakdown in the linguistic components/content of language: 1.Phonemic Paraphasias speaking a word with an error in letter sound Phonology term applied to sound pattern of language Phoneme is the smallest segment of spoken language (phoneme = k in kiss, p in pencil). Sounds/phonemes are ordered to produce words Patients may be impaired in their ability to organise letter sounds in sequence which results in phonemic paraphasias (word is distorted with unintentional sound) An error occurs in a letter sound f - ork Real word approximations e.g. pipe = hike, no, pike, no pipe; snail for stale Neologisms e.g. fencil for pencil, poot for suit Phonemic decoding critical for language comprehension Necessary to distinguish pear from bear, fit from bit
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  • 2. Semantic Paraphasias speaking an incorrect word semantically related to the target word Semantics meanings of words e.g. mother, aunt; canary is a small yellow bird Breakdown in understanding referential meaning of words linking sound to meaning One word, usually related semantically, replaces another Results in semantic paraphasias orange for apple, sister for brother, him for her animal for giraffe Unintended and distinct from word-finding/naming difficulty (e.g. its that green thing you eat with fingers [asparagus])
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  • 3. Agrammatism/Paragrammatism Syntax words strung together to form phrases or sentences in a complex way that obeys grammatical rules A loss of syntactic production results in agrammatism: Brocas Aphasia Speech is simplified, reduction in prepositions (e.g.on ) articles (the, a/an), inflections - ing, verbs, tense, person, plurals The production of sentences with incorrect use of syntactic elements results in paragrammatism Wernickes Aphasia Running or increased speech production, with a tendency to acceleration. Content lacks information-conveying nouns and verbs. Phrases do not make sense together because abnormal syntactic inflections produced or due to paraphasias including neologisms Paragrammatism sometimes called word salad
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  • Causes of Aphasia: Neuroanatomical location of lesion rather than the aetiology that essentially determines the nature of the language deficit Focal lesions CVA (stroke) usually middle cerebral artery territory infarct or haemorrhages Abrupt onset Aphasia most pronounced at time of onset or shortly thereafter Recognisable syndromes usually emerge after acute phase Intracranial tumours and other space occupying lesions (SOL) (cerebral abscess) with symptoms worsening as SOL increases Traumatic brain injury Dementias rarely cause classical aphasic syndromes Alzheimers Disease Frontotemporal lobar degeneration: semantic dementia, progressive non-fluent aphasia
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  • Mutism: Mutism is a complete failure of language or speech output. May be due to Severe aphasia Acute global aphasia: severely impaired comprehension, reading and writing Acute Brocas aphasia: comprehension relatively normal, writing may be unaffected An articulation (speech) disorder Aphemia (pure word mutism): comprehension, repetition and reading/writing normal Psychiatric condition
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  • Causes of mutism: CVA (Stroke) Disorders of articulation: CVA (Stroke, Motor neurone disease, poliomyelitis, Lyme disease, Tumour) Degeneration of the basal ganglia (Huntingtons Disease, Parkinsons Disease) Psychiatric disorders Catatonia in Schizophrenia, Severe depression and PTSD Hysterical aphonia (Psychogenic voice disorder) Elective mutism
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  • Left hemisphere and language: the left hemisphere is strongly dominant for language in most humans Language is generally located in the left hemisphere HemisphereLanguageDominance HandednessLeftRightBilateral Left50-70%15-19%15-20% Right96%4%0
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  • Classical Aphasic syndromes: Aphasic syndromes proposed by Lichtheim (1885) drawn from work of Broca and Wernicke Two cortical areas within the dominant (left) hemisphere were identified as having specialised language function 1.Anterior or motor language (Brocas) area 2.Posterior or sensory language (Wernickes) area
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  • 1.Anterior or motor language (Brocas) area Broca (1861) described a patient Leborgne whose language output was non-fluent and limited to the word tan. He could understand spoken language, non-verbal communication and could communicate through gestures and facial expression Lesion: center of the lesion was the inferior frontal convolution of left hemisphere Broca related the lesion to the patients expressive language dysfunction
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  • Leborgnes (Tans) brain on autopsy
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  • 2. Posterior or sensory language (Wernickes) area Wernicke (1874) described a patient with fluent language output that contained words with sound errors (phonemic paraphasias) and semantic errors, who did not understand spoken language Lesion: posterior part of the superior temporal gyrus Proposed that receptive language processing was localised adjacent to primary sensory cortex and expressive language processes was adjacent to primary motor cortex.
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  • Classification of Aphasia Syndromes Terminology, classification schemes vary Initially dichotomous classification scheme 1.Expressive, non-fluent, motor, anterior or Brocas aphasia 2.Receptive, fluent, sensory, posterior or Wernickes aphasia Lichtheim (1885) developed seven syndromes linked to the lesion sites of Broca and Wernicke: Brocas aphasia Wernickes aphasia Pure motor speech disorder articulation disorders Pure word deafness auditory word recognition disorder Transcortical motor aphasia Transcortical sensory aphasia Conduction aphasia
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  • Classification system of lesion based aphasia syndromes Three additional syndromes described by Benson (1979): Anomic aphasia Global aphasia Isolation of the language zone (Isolated aphasia) Neuroanatomical model developed further by Geschwind (1965) to include the anatomical link between Wernickes and Brocas area white matter tract arcuate fasciculus
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  • Comprehension i)Of spoken language: When you hear a word spoken, auditory information is transmitted to the primary auditory cortex and subsequently relayed to Wernickes area/inferior parietal lobe in the dominant hemisphere for translation ii)Of wri