• Questions from Week 9 lecture

– Exam content– Apraxia/Dyspraxia (disturbance/difficulty) – Apraxia Model– Differentiating Apraxia/Aphasia – Prosopagnosia vs. Variant of Prosopagnosia

in Semantic dementia

• 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

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 person’s name vs progressive difficulty with face recognition/and or naming (semantic knowledge about person is lost)

Aphasia

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

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

• 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 Broca’s aphasia rather than a disorder of speech

• Aphasia is a disorder of Language

• Dysarthria and Speech Apraxia are disorders of (the motor control) of Speech

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

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. “it’s that green thing you eat with fingers” [asparagus])

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:– Broca’s 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– Wernicke’s 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”

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– Alzheimer’s Disease– Frontotemporal lobar degeneration: semantic dementia,

progressive non-fluent aphasia

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 Broca’s aphasia: comprehension relatively normal,

writing may be unaffected

– An articulation (speech) disorder• Aphemia (pure word mutism): comprehension, repetition and

reading/writing normal

– Psychiatric condition

Causes of mutism:• CVA (Stroke)

• Disorders of articulation:– CVA (Stroke, Motor neurone disease, poliomyelitis,

Lyme disease, Tumour)– Degeneration of the basal ganglia (Huntington’s

Disease, Parkinson’s Disease)

• Psychiatric disorders– Catatonia in Schizophrenia, Severe depression and

PTSD– Hysterical aphonia (Psychogenic voice disorder)– Elective mutism

Left hemisphere and language: the left hemisphere is strongly dominant for language in most humans

Language is generally located in the left hemisphere

Hemisphere Language Dominance

Handedness Left Right Bilateral

Left 50-70% 15-19% 15-20%

Right 96% 4% 0

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 (Broca’s) area

2. Posterior or sensory language (Wernicke’s) area

1. Anterior or motor language (Broca’s) 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 patient’s expressive language dysfunction

Leborgne’s (Tan’s) brain on autopsy

2. Posterior or sensory language (Wernicke’s) 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.

Classification of Aphasia Syndromes

Terminology, classification schemes vary

• Initially dichotomous classification scheme

1. Expressive, non-fluent, motor, anterior or Broca’s aphasia2. Receptive, fluent, sensory, posterior or Wernicke’s aphasia

• Lichtheim (1885) developed seven syndromes linked to the lesion sites of Broca and Wernicke:

– Broca’s aphasia– Wernicke’s aphasia– Pure motor speech disorder – articulation disorders– Pure word deafness – auditory word recognition disorder– Transcortical motor aphasia– Transcortical sensory aphasia– Conduction aphasia

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 Wernicke’s and Broca’s area – white matter tract “arcuate fasciculus”

Comprehensioni) Of spoken language: When you hear a

word spoken, auditory information is transmitted to the primary auditory cortex and subsequently relayed to Wernicke’s area/inferior parietal lobe in the dominant hemisphere for translation

ii) Of written words: Visual impulses transmit to the primary visual cortex in the occipital lobe are relayed to the angular gyrus from which it is sent to Wernicke’s area

Expression

i) Following translation the information is passed to Broca’s area via the arcuate fasciculus (subcortical white matter tract)

ii) Broca’s area passes information to the primary motor cortex of each hemisphere. Instructions are sent via the motor pathways to the muscles of the speech organs to produce a verbal response

Boston Aphasia Classification System

• Major Classification System (Benson, 1979)• Recognises eight subtypes of aphasia • Assess: Boston Diagnostic Aphasia Examination

1. Broca’s Aphasia. Lesion of the expressive speech area2. Wernicke’s Aphasia. Lesion of the receptive speech

area3. Conduction Aphasia. Disconnection of the expressive

and receptive areas4. Global Aphasia. Extensive lesion involving both

expressive and receptive areas

Boston Aphasia Classification System

5. Transcortical Motor Aphasia6. Transcortical Sensory Aphasia7. Isolated Aphasia8. Anomic Aphasia

Boston Aphasia Classification System

• Syndromes 1 to 4

- Associated with lesion of the central speech areas or their connections

- Aetiology: Most likely to result from CVA involving one or more of the branches of the middle cerebral artery

Boston Aphasia Classification System

• Syndromes 5 to 8- Associated with lesions surrounding the central

speech areas- ‘Watershed’ or ‘Border-zone’ area- Aetiology: Infarction between anterior and

middle cerebral arteries, and between the middle and posterior cerebral arteries

- Repetition: Disordered in groups 1 to 4, intact in groups 5 to 8

Blood supply: Blue = Anterior Cerebral ArteryPink = Middle Cerebral ArteryYellow = Posterior Cerebral Artery

Boston Aphasia Classification System

Each syndrome associated with particular cluster of language symptoms (not all of which need to be present for categorisation)

Clusters of certain symptoms have shown discriminant validity between cases of Broca’s, Wernicke’s, conduction and anomic aphasia (Strauss, Sherman & Spreen, 2006)

Scale profiles aid in classification but a large range of aphasics patients are not classifiable because they have mixed symptomatology

Some cautions with the lesion based classification systems of aphasia:

1. Level of description of language deficit: – Classical syndrome language abnormalities reflect the patients

ability to perform entire language tasks (fluent/non-fluent speech, comprehension, repetition, naming) – do not examine the linguistic details of language impairment (phonology, semantics, syntax, prosody). Both Broca’s and Wernicke’s may have problems with expression.

2. Do not cover all patients symptoms: – There may be heterogeneity of deficits across patients with the

same syndrome (e.g., Broca’s – comprehension of speech may be normal in some, moderately disturbed in others; Benson & Geschwind, 1971)

– May result in a large number of patients showing mixed rather than pure symptomatology

3. Syndromes may not localise to expected lesion site:– general correlation between lesion site and syndrome– classical syndromes are related to lesion sites in

cases of rapidly developing lesions e.g., stroke (but not applied to acute and subacute phases of illness)

– in chronic phase at least 15% of patients have lesions not predictable from their syndromes

– Broca’s aphasia requires larger lesion to sylvian fissure encompassing much of the left fronto-parietal opercula, insula and white matter in territory upper middle cerebral artery

Site of damage causing Broca's aphasia. The areas infarcted in 14 patients, all diagnosed as suffering from Broca's aphasia. All 14 lesions were then superimposed, indicating a focus of damage in the posterior part of the left inferior frontal gyrus.

From Kertesz A, Lesk D, McCabe P: Arch Neural 34:590.

Site of damage causing Wernicke's aphasia. The areas infarcted in 13 patients, all diagnosed as suffering from Wernicke's aphasia. All 13 lesions were then super imposed, indicating a focus of damage in the posterior part of the left superior temporal gyrus.

From Kertesz A, Lesk D, McCabe P: Arch Neurol 34:590.

Classifying aphasia syndromes

• Four aspects of language 1. Fluency

• Divides syndromes into those associated with anterior (non-fluent) vs posterior (fluent) lesions

• Non-fluent: slow, laborious, lack of melody/rhythm, poor articulation, shortened phrases, preferred use of verbs and nouns

– Lesion: anterior to sylvian fissure

• Fluent: normal rate, preserved rhythm/melody good articulation, normal phrase length

– Lesion: posterior to sylvian fissure in Wernicke’s area or basal temporal lobe

2. Repetition– Defective repetition:

• Lesion: perisylvian area in the territory of the middle cerebral artery, incorporating Broca’s area, insula and Wernicke’s area, and arcuate fasciculus in between them

– Preserved repetition (cf spontaneous speech):• Lesion: sparing of primary language areas (Broca’s and

Wernicke’s); lesion is outside of sylvian areas

– Syndromes associated with sparing of repetition are termed transcortical (transcortical motor or transcortical sensory)

• Comprehension

– Deficits on gross examination associated with:• Lesion: Damaged temporal lobe

– Note** If syntactic comprehension tests are used most dysphasic patients (regardless of site of lesion) will have some comprehension deficit

• e.g. “Pick up the blue circle OR the red square” (2 step command from the Token Test)

• “Put the pen on top of the book then give it to me” (3 step command from Western Aphasia Battery)

• Naming– Ability to name objects, or line drawings is

impaired in most aphasic patients to some degree

3

30. harmonica…….. (musical instrument)

Copied from Boston Naming Test for educational purposes

1. Broca’s Aphasia

- Non-fluent speech - Impaired repetition- Comprehension relatively intact- Naming poor – improves with phonemic cues, and

multiple choice

Speech:- Slow and effortful; phonemic paraphasias- Agrammatic and telegrammatic (containing a

predominance of content words)

Writing:- Misspellings, letter omissions, perseverations,

agrammatic sentences- Copying better than to dictation

Reading:- Reading aloud poor- Comprehension relatively spared

Frequent Associations- Speech apraxia- Dysarthria- Right Hemiplegia (paralysis) or hemiparesis (weakness)

– most notable in the arm and face- Ideomotor apraxia

Neuropathology- Extensive damage to fronto-parietal region to area

supplied by anterior branch of middle cerebral artery- Evolves over time from global aphasia

Spontaneous Language: ‘Cookie jar theft’: Boston Diagnostic Aphasia Examination

Copied for educational purposes

youtube.com broca’s aphasia

2. Wernicke’s Aphasia

- Fluent speech- Repetition poor- Comprehension impaired- Naming impaired – not aided by phonemic cues or multiple choice

Speech:- Content: Word substitutions (phonemic and semantic paraphasias)

and combinations, sometimes neologistic jargon- Incapable of monitoring own output - Sentences meaningless and cannot be understood by others

Writing:- Legible – letters formed (rarely have a concomitant hemiplegia)- Content: Aphasic, disjointed, repetitive text, few nouns and verbs

Reading:- Reading aloud and reading comprehension both

disturbed (occasional patients may have superior reading ability)

Associated deficits:- Often none- Visual field defect - Quadrantanopia may be evident

Neuropathology- Destruction of Wernicke’s area- Damage to superior posterior temporal lobe

youtube Wernicke’s aphasia

3. Conduction Aphasia

- Fluent speech paraphasic (mainly phonemic) - Repetition highly abnormal – strings of phonemic

approximations- Comprehension relatively intact- Naming often disturbed

Speech:- Hesitation due to word finding difficulties (dysprodic

speech)

- Writing:- Spelling poor with omission, reversal and substitution of

letters- Words often interchanged and misplaced

Reading:- Reading aloud similar to repetition highly abnormal- Silent reading may be good

Frequent Associations:- Often none- Hemianesthesia (loss of sensation down one side of the

body)- Visual field defects (hemianopia or quadrantanopia)

Neuropathology:- Severing of the arcuate fasciculus in classical syndrome- More commonly results supramarginal gyrus lesion- Conduction aphasia often occurs in recovery from

Wernicke’s aphasia

4. Transcortical AphasiasEarly aphasiologists postulated a transcortical

pathway linking auditory language and verbal motor centre bypassing meaning – now used descriptively

4a) Transcortical Motor Aphasia

- Shares many qualities with Broca’s aphasia- Non-fluent speech: reduction in the quality and complexity

of spontaneous speech (non-fluent) and dysarthric- Few paraphasic errors- Repetition: preserved- Comprehension: very good- Writing: similar to spoken output- Lesions: dominant frontal lobe anterior and superior to

Broca’s area generally due to anterior cerebral artery infarction

4b) Transcortical Sensory Aphasia

– similar to Wernicke’s aphasia– Fluent speech: contaminated by semantic

paraphasias– Comprehension: defective at level of linking sound to

meaning– Repetition: words and long sentences intact but

cannot extract meaning from language – Reading and writing: similar to Wernicke’s aphasia

(disturbed)– Lesion: border zone of parieto-temporal junction

5. Anomic Aphasia

- Anomia (the inability to name to confrontation) common to most aphasic patients

- When most prominent feature of the aphasia the condition is referred to as anomic aphasia

- Common syndrome- Often the end point of recovery from other aphasic conditions

Speech- Fluent but empty due to lack of substantive wordsMay be circumlocutory (providing a description of the word) or abrupt

cut-offs (trying to find word) in mid sentence

Writing: Near Normal

Neuropathology:- Non-localising; Acute onset suggests lesion temporo-parietal area

6. Global (total) AphasiaAll major language functions seriously

disturbed

Neuropathology:Typically extensive left hemisphere damage Syndrome has been reported even in cases

where Wernicke’s area is sparedMay result from subcortical syndromes

which functionally isolate Broca’s area

7. Isolation (mixed-transcortical) Aphasia

- Rare- Intact repetition in association with marked reduction of

spontaneous speech and poor comprehension- Voluntary aspects of language lost (spontaneous speech,

initiation of speech)- Resembles global aphasia except for preservation of

repetition

Neuropathology:Anterior and posterior parts of watershed area

Tests of Language:• Spontaneous language:

– Open questions (Western Aphasia Battery)• How are you?• Have you been here before?• Tell me a little about whyy ou are here?

– Complex picture description:• ‘cookie jar theft’ picture from Boston Diagnostic

Aphasia Examination

• Confrontation naming:• line-drawings (Boston Naming Test)

• Comprehension:– Increasingly syntactically complex commands

• one step, two step, three step commands• Token Test, Western Aphasia Battery)

• Word-picture matching tests:• single-word (semantic) comprehension (Peabody Picture

Vocabulary Test)

• Aphasia batteries: – Boston Diagnostic Aphasia Examination– Western Aphasia Battery– Psycholinguistic Assessment of Language

Processing in Aphasia (PALPA)