Understanding Aphasias

Chairperson - Dr Sanjeev Kumar Presenter - Dr Nikhil Govil

Introduction

• 2 important functions which put humans ahead of other primates is the use of thumb and well developed system of communication(language )in human beings

• Language- is the knowledge of a symbol system used for interpersonal communication.

• Speech- motor act of communicating by articulating verbal expression.

• To understand the disorders of language we should be well acquainted with the areas of human brain involved in this complex process.

If only mice could read

Neuroanatomy of language

Lateral surface of brain

Blood supply to speech areas of brain

• Broca’s area and wernicke’s area are supplied by middle cerebral artery

• Visual cortex supplied by posterior cerebral artery

• Deep white matter and supplementry cortex supplied by anterior cerebral artery

Lateralization of funcions

Left hemisphere-• Sequential analysis• Problem solving• language

Right hemisphere-• Simultaneous analysis• Visuo-spatial skill• Emotional functions• Music

Pathway of language• Wernicke-Geschwind Model

1. Repeating a spoken word

•Arcuate fasciculus is the bridge from the Wernicke’s area to the Broca’s area

Pathway of language(Contd.)

• Wernicke-Geschwind Model2. Repeating a written word

Angular gyrus is the gateway from visual cortex to Wernicke’s area

Definitions pertaining to aphasia

• An aphasia is a multimodal language disorder, i.e. it is a neurologically conditioned impairment of language ability in all its modalities, e.g. speaking, comprehending, reading, writing

• Syntax(grammar)-admissible combination of words or phrases and sentences.

• Semantics- the study of meaning.• Phoneme- the smallest unit of sound that signals

meaning.(e.g. k is a phoneme in kit/skill)• Morpheme- smallest semantically meaningful unit of

language.(e.g. dog, cart )

Definitions (contd.)• Fluency- Expression of thoughts using a smooth,

uninterrupted flow and rate of speech.• Repetition- Ability to accurately reproduce verbal stimuli.• Naming- Ability to retrieve and produce a targeted word.• Paraphasias- these are the patterns of speech errors

– Phonemic: substitution or transposition of the targeted phoneme(e.g pencil is substituted by pentil)

– Semantic: error is related or in the same category but is incorrect (e.g pencil is substituted by pen)

History of Aphasias• In 1800’s Dr Paul Broca was the first to localise the

language function in brain. one of his patients could only produce a single syllable “tan”.

• Patient’s autopsy report revealed a lesion in posterior part of the left 3rd frontal convolution which was termed later as broca’s area

• A language problem distinct from Broca’s aphasia was first described by Carl Wernicke (in 1908) which involved Damage to the boundary of the temporal and parietal lobes later termed as wernicke’s area

Aphasia facts• Over 1 million people in America are suffering from this

socially and mentally devastating disorder.• Every year about 200,000 new cases are added and the

incidence is going to increase further.(yet no authentic demographic data available in India)

• Overall incidence of aphasia is more than the combined incidence of cerebral palsy, muscular dystrophy and Parkinson's disease.

Aphasia-risk factors• Uncontrollable factors

– Age– Gender– Racial or ethnic background– Family history

• Controllable factors– Hypertension– Diabetes– Tobacco smoking– Alcohol use

Causes of aphasias• Stroke (most common

cause)• Degenerative

diseases(e.g. parkinson’s disease)

• Head injury• Brain tumors• Multiple sclerosis• Landau kleffner syndrome

Causes of aphasia(contd.)• Infectious diseases like

HSV encephalitis• Dementias(alzheimer’s,fro

ntotemporal dementias)• Cerebral abscess• Epilepsy• Migraine

• Dissection syndromes• Polyarteritis nodosa• Cerebral venous

thrombosis• Central pontine

myelinolysis• Very rarely seen with

fentanyl patches

Types of aphasias• Aphasias can be broadly

classified in 2 ways• First on the basis of

fluency of speech1. Fluent aphasias2. Non fluent aphasias3. Pure aphasias• On the basis of cause 1. Primary2. Secondary

• Fluent aphasias- fluent speech but difficulties either in auditory/ verbal comprehension or in the repetition of words, phrases, or sentences spoken by others

1. Wernicke’s aphasia2. Anomic aphasia3. Conduction aphasia4. Transcortical sensory

aphasia

Types of aphasias (contd.)Non fluent aphasias-difficulties in articulating but

relatively good auditory and verbal comprehension

1. Broca’s aphasia2. Global aphasia3. Transcortical motor

aphasia4. Mixed transcortical

aphasia

Pure aphasias -these are selective impairments in reading, writing, or the recognition of words

1. Alexia/pure word blindness

2. Agraphia3. Pure word deafness4. Alexia with agraphia

Types of aphasias(contd.)• Primary aphasia due to problems with cognitive language-

processing mechanisms, which can include: Transcortical sensory aphasia, Semantic Dementia, Apraxia of speech, Progressive nonfluent aphasia, and Expressive aphasia -

• Secondary aphasia result of other problems, like memory impairments, attention disorders, or perceptual problems, which can include: Transcortical motor aphasia, Dynamic aphasia, Anomic aphasia, Receptive aphasia, Progressive jargon aphasia, Conduction aphasia

Wernicke’s aphasia• Anterior/receptive/fluent /jargon• Abnormal language

comprehension• Fluent meaningless speech• Paraphasias – errors in

producing specific words• Semantic paraphasias –

substituting words similar in meaning (“barn” – “house”)

• Phonemic paraphasias – substituting words similar in sound (“house” – “mouse”)

Wernicke’s aphasia(contd.)• Neologisms – non words • Grammar relatively

preserved• Poor repetition and

naming• Impairment in writing• Associated with damage to

the temporal lobe near but not including the Heschel’s gyrus (primary auditory cortex; the patients are not deaf)

• Occurs as a result of occlusion of inferior division of left middle cerebral artery

• Neighborhood signs include superior quadrantanopsia,limb apraxia, finger agnosia, acalculia, agraphia.

• The patient is usually unaware of his deficit.

Wernicke’s aphasia speech sample

• Clinician: “Tell me where you live.”• Patient: “Well, it’s a meender place and it has two … two

of them. For dreaming and pinding after supper. And up and down. Four of down and three of up …”

• Clinician: “What’s the weather like today?”• Patient: “Fully under the jimjam and on the altigrabber.”

(Brookshire 2003:155)

Broca’s aphasia• Expressive/anterior/non

fluent aphasias• Nonfluent speech, short

phrases,word finding pauses, makes errors in grammar, omits function words (Telegraphic speech)

• Poor repetition and naming

• Comprehension preserved

Broca’s aphasia (contd.)• Speech is sparse

containing 10-15 words/minute)

• Can be mild or severe• Broca’s aphasia is

characterised by damage to left 3rd frontal convolution located near inferior frontal gyrus

• Blockage of superior division of middle cerebral artery

• Mainly verb naming deficits i.e. the patient will have difficulty in naming actions

• Neighborhood signs include right hemiparesis (face,arm affected more than legs)

• The patients are aware of their deficit

Broca’s aphasia speech sample• Examiner: Describe this

picture.• Patient: uh … mother and

dad … no … mother … dishes … uh … runnin[g] over … water … and floor … and they … uh … wipin[g] dis[h]es … and … uh … two kids … uh … stool … and cookie … cookie jar … uh … cabinet and stool … uh … tippin[g] over … and … uh … bad … and somebody … gonna get hurt.

Global aphasia• Associated with extensive

left hemisphere damage• Deficits in comprehension

and production of language

• Right hemiplegia(face and arm worse than leg),right homonymous hemianopia is very common

• Occlusion of I.C.A/M.C.A

Conduction aphasias• As explained by the

Wernicke-Geschwind model, conduction aphasias occur as a result of damage to the fibres connecting the Broca’s and the Wernicke’s area.

• Difficulty in repeating what was just heard (no repetition or paraphasias)

• Comprehension and production intact

Transcortical motor aphasia• Transcortical motor aphasia: Comprehension and repetition

are preserved, however, speech is nonfluent• Due to Infarction in the watershed area between anterior and

middle cerebral atreries in the frontal lobe.

Transcortical sensory aphasia• Transcortical sensory aphasia: Repetition is preserved,

speech is fluent but comprehension is impaired• Due to Lesion in the parieto-occipital cortex

Mixed transcortical aphasias• Also called as syndrome

of isolation of speech area• Repetition intact• Patient can neither

comprehend nor able to produce spontaneous speech.

Anomic aphasia• Amnesic /nominal aphasia• Comprehension intact• Fluent speech• Repetition is preserved• Cannot name

objects/verbs• Object naming problems

tend to be a result of temporal damage, whereas verb naming problems tend to be a result of left frontal damage.

“What is this object called?”

“I know what it does…You use it to write on a paper”

Pure aphasias• Pure word deafness-patient can not comprehend spoken

language, though their verbal output and reading comprehension are intact. site of lesion is bilateral superior temporal(heschl) gyrus.

• Pure word blindness(alexia)- patients have normal expressive speech,naming,repetition,normal auditory comprehension and even normal ability to write but they are unable to read.it is mostly associated with stroke in territory of left posterior cerebral artery.

• Alexia with agraphia- also called as angular gyrus syndrome/central alexia.writing as well as reading skills are lost.lesion involves angular gyrus in left inferior parietal lobule

Miscellaneous aphasias• Agraphia- is the inability to write and spell (when writing),

this inability is due to damage to the superior and inferior parietal lobules.

• Aphemia (pure word mutism)- Impaired speech with intact comprehension and writing. Associated with lesions in or around Broca's area, involving the lowermost part of the precentral gyrus.

• Anterior subcortical aphasia- involving non fluent speech with dysarthria, but with intact repetition

• Thalamic aphasia causing fluent speech with paraphasias, but with relatively preserved repition and comprehension.

Diagnosis of aphasias

1. testing following aspects of language

• Fluency• Content• Repetition• Naming• Comprehension• Reading• writing

• Various batteries of tests assessing language-

1. Boston diagnostic aphasia examination

2. Western aphasia battery3. Halstead screening test4. Token test

Diagnosis of aphasia(contd.)

2. Detailed neurological examination

3. Detailed mental status examination

4. Neuroimaging (CT AND MRI)

5. EEG

Conditions mistaken for aphasias

• Developmental disorders of speech-many children with brain damage(antenatal,perinatal,postnatal) and mental retardation learn speaking ,reading and related skills incompletely or not at all.

• A developmental suppression of motor fluency of speech is very common. stuttering or stammering is not a part of aphasia

• Congenital deaf-mutism leading to early damage to the function of hearing influences the development of speech.

Conditions mistaken for aphasias

• Pure dysarthria hampers pronunciation and intelligibility of speech but language, vocabulary, grammar, reading,writing and auditory comprehension are intact.

• Disorders of phonation occur due to diseases of the larynx, vocal cords and respiratory weakness

• Pervasive disorders in children leading on to regression of normal acquired speech and communicative ability, and other cognitive functions such as in Autism,Aspergers syndrome and Rett syndrome.

Conditions mistaken for aphasias(contd.)

• Patients with conversion reaction, malingering may become mute,speak in whispers in a bizarre, abnormal manner.

• Speech in psychosis, particularly in schizophrenia may be sparse or excessive, bizarre and absurd.howsoever absurd the thought and speech in a patient with schizophrenia, grammar and logic are largely retained

• Patient with metabolic encephalopathy or delirium may have difficulty naming and fail to follow commands.but the fluctuating level of consciousness, agitation, hallucinations and asterixis differntiate it from aphasias.

Conditions mistaken for aphasias(contd.)

• Patients with akinetic mutism resulting from lesions of mesial frontal region may demonstrate a paucity of speech output and poor response to commands. observation of decreased motor responses, not restricted to speech, helps differentiating it from aphasia.

• Verbal apraxia of speech characterized by an impaired ability to coordinate the sequential, articulatory movements necessary to produce speech sounds in the absence of involvement of articulatory apparatus.

• Visual and tactile agnosia may mimic anomic aphasia

Prognosis and recovery

Prognosis and recovery from aphasias mainly depend upon the following factors-

1. Age2. Causes of brain injury3. Types of aphasias4. Position and size of

brain lesion5. Severity of aphasia in

the initial phase6. Rehabilitation services7. handedness

Treatment of aphasias

1. Treat the cause2. Speech and language

therapy3. Newer techniques• Constraint induced

aphasia therapy• Melody intonation

therapy• Transcranial magnetic or

electrical stimulation

4. pharmacotherapy-• Memantine• Amphetamine• Donepezil• Piracetam• Antidepressant• Bromocriptine5. Family and peer support

Summary of aphasias

Thank you

APHASIAS

FLUENT NON FLUENT

IS COMPREHENSION INTACT?

YES NO

GLOBAL APHASIA

REPETITION INTACT?

YES NO

IS COMPREHENSION INTACT?

YES

YES

NO

NO

REPETITION INTACT?

REPETITION INTACT?

WERNICKE’S APHASIA

TRANSCORTICAL SENSORY APHASIAANOMIC

APHASIACONDUCTION APHASIA

YES NO

MIXEDTRANSCORTICAL APHASIA

BROCA’SAPHASIA

REPETITION INTACT?

YES NO

TRANSCORTICAL MOTOR APHASIA