ANATOMICAL BASIS OF APHASIA

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Anatomical basis of Aphasia:

Anatomical basis of Aphasia Dr. Nazim Nasir Resident Department of Anatomy JNMCH,AMU, ALIGARH

Definitions :

Definitions Speech is a highly evolved function of cerebral cortex. Speech is the human faculty by which thought processes are symbolically expressed. Speech is the vocalization form of communication. It is based upon the syntactic combination of lexical and names that are drawn from very large vocabularies(usually>10,000 different words) Each spoken word is created out of the phonetic combination of a limited set of vowels and consonant speech sound units.

Components of speech:

Components of speech Speech is the mechanical function of one’s ability to communicate in oral language It includes; Language production Phonation & Articulation

Speech and hemispherical dominance:

Speech and hemispherical dominance Speech is the function of cerebral hemisphere. It is undertaken by the dominant hemisphere. 9 out of 10 human have right handedness. 90% of human also have left hemispherical dominance. Rest 10% have left handedness. 7 out of these 10% have left hemispherical dominance. 3 out of the 10% have right hemispherical dominance. Thus 97% of human have left hemispherical dominance. Only 3% have right hemispherical dominance. It also means speech is a function of left hemisphere in 97 out of 100 and right hemisphere in only 3%.

Language :

Language Language is the symbolization of ideas Its the ability to convert thought into comprehensive words. It consists of five parameters. Speaking Hearing Repeating Reading Writing Perisylvian region

Wernicke’s Area:

Wernicke’s Area The auditory comprehension of spoken speech takes place in posterior end of the superior temporal gyrus. Karl Wernicke German neurologist Identified it Described the pathway Connection to Broca’s area Arcuate fasciculus. This area is neuroanatomically described as posterior part of Brodmann area 22.

Broca’s area:

Broca’s area The motor area for spoken speech which is situated in the posterior part of left inferior frontal gyrus. Peirre Paul Broca French surgeon Described it in 1865 Two patients who lost speech Autopsy done showed Lesion in lateral frontal lobe This area is neuroanatomically described ass the posterior part of Brodmann area 44 and 45.

Conduction area:

Conduction area A deep, white matter tract, connecting the Wernickes area to Brocas area. Also called Arcuate fasciculus Latin word Curved bundle Neural tract Important in dominant hemisphere Lesion causes conduction aphasia. Repetition deficits arise following damage to the arcuate fasciculus of the dominant hemisphere.

Exner’s area:

Exner’s area An area of the brain just above Broca’s area and anterior to the primary motor control area. Seigmund Exner Austrian physiologist 1846-1926 Area for writing Close to area for hand movement Damage results in Agraphia . This area is neuroanatomically described as the posterior part of Brodmann area 6.

Reading area:

Reading area An area of the brain just medial to left occipital lobe and in the splenium of corpus callosum. Centre for reading Receives impulses fro eye. Transmits to association area Analyses red matter Passes to arcuate fasciculus Lesion- pure word blindness. This area is neuroanatomically described as the posterior part of Brodmann area 17.

Areas of brain :

Areas of brain 44, 45 4, 6 41 39 22 17 18, 19

Speech mechanism:

Speech mechanism Reception of sound Signal by auditory area Interpretation of words on wernickes area Information transmitted via Arcuate fasciculus Activation of broca’s area For word formation To motor cortex that control Speech muscles

Speech in response to hearing:

Speech in response to hearing Primary Auditory area Wernicke’s area Broca’s speech area Primary motor cortex Brain stem Muscles of larynx

Pathway in the process of reading:

Pathway in the process of reading Primary visual cortex Visual Ass. area WERNICKE’S SPEECH AREA BROCA’S SPEECH AREA PRIMARY MOTOR CORTEX BRAIN STEM MUSCLES OF LARYNX

APHASIA:

APHASIA Loss of lang. due to dysfunction of the central mechanism in the brain is called aphasia. Minor disorders of the same is called as dysphasia Eg . Right hemiplegia producing dysphasia. Dysfunction of the peripheral mechanism of speech leading to defective articulation is termed dysarthria . Eg . LMN facial palsy, pseudobulbar palsy. Loss of vioce due to dysfunction of the vioce producing mechanism is called dysphonia . Eg . Vocal cord paralysis, acute laryngitis. Loss of ability to read: alexia Loss of ability to write: agraphia

Examination of aphasia:

Examination of aphasia Spontaneous speech Whether pt. spont . Ask for food, urination etc. Comprehension Whether pt. can obey commands Repetition Whether pt. can repeat phrases or numbers. Naming Whether pt. can name an object. Reading Whether pt. can read, understand and obey Writing Whether pt. can write down the answers.

Testing spontaneous speech:

Testing spontaneous speech Fluency Whether speech is fluent without hesitations Uninterrupted by searching for a forgotten word Effort taken for speech See whether the pt. has effortless/effortful speech Vocabulary See whether there is any word finding difficulty Whether pt stammers and stumbles Ability to speak in full sentences Or pt. is able to talk only in phrases Grammer Whether the grammer is correct or not

Testing comprehension:

Testing comprehension Whether pt. can hear and understand speech? Tested by asking the pt. to obey commands Ask the pt to show the tongue, close eyes, lift a limb Fluency is preserved or not Speech whether fluent without hesitations? Use of par aphasias Use of descriptive phrase instead of a forgotten word Use of neologism Invented word and nonsense words Jargon aphasia Extreme example of the above speech devoid of meanings

Testing Repitition:

Testing Repitition Pt is asked to repeat a simple sentence It has to be clearly stated by the examiner Eg . Today is Thursday, the january 13 th , 2011 See whether the pt is able to repeat what you say Remember never to shout at a aphasia pt. Hearing is usually normal in these patients. In a patient with left frontal lesion They can repeat simple words and phrases In a pt. with posterior lesions in the angular gyrus They cannot repeat what examiner says. This is characteristic feature of conduction aphasia This function is preserved in transcortical aphasia

Testing for Naming :

Testing for Naming Pt. is shown an object and asked to name it A commonly used object should be shown Eg . Pen or match box See whether the pt is able to name the object Pt may be handed over the object Or asked to demonstrate the use of the object In Anomic aphasia or nominal aphasia Pt is unable to name it, but use it even Auditory comprehension, repetition, reading and writing These are usually preserved in such a patient Memory testing otherwise will be normal This function is preserved in transcortical aphasia

Aphasia syndromes:

Aphasia syndromes

Wernicke’s aphasia:

Wernicke’s aphasia Fluent Increased verbal content Para- grammatism -speech running Phrase length-generally greater than five words Grammatical sentences(or close to normal) Paraphasic errors(literal or verbal) Literal- sound substitution with errors (winging ringing) Symantic - word substitution(sister for mother) Neologism(made up words) Logorrhea-inability to stop speaking Severely impaired auditory comprehension MCA territory stroke- left superior temporal lobe

Broca’s aphasia:

Broca’s aphasia Non fluent Telegraphic speech Reduced verbal content Phrase length-generally less than four words Agrammatical sentences(or frequent errors) Mostly content words (nouns and verbs) Absence of functional words(preposition & conjunction) The matter is conveyed anyway Functional comprehension is present But trouble following complex grammatical statements Reading loud I not possible; but can read and obey MCA territory stroke—left frontal lobe

Conduction aphasia:

Conduction aphasia Relatively uncommon Spont . Speech is fluent Considerable word finding difficulty Preserved auditory comprehension Significant difficulty with repetition Literal paraphasia Self correction Numerous pauses Filled pauses Reading deficit-variable Writing deficit- variable Lesion; left superior temporal area, supramarginal gyrus

Nominal aphasia:

Nominal aphasia Primary deficit- word finding and naming Speech output is fluent with numerous pauses Pauses may be filled with circumlocutions(The use of unnecessarily wordy and indirect language) eg . Describing the function of an object but the name cannot be retrieved. Auditory comprehension is intact Reading and writing are also intact Last localized of all aphasias Focal damage to left temporal and parietal Usually residual of good recoevery from other aphasias Also indicates good prognosis if seen in acute stage.

Global aphasia:

Global aphasia Severe impairment in all modalities Speaking, listening, reading, and writing Severely impaired auditory comprehension Very limited speech output Only few understandable utterances Some areas of spared speech function Utilized in communication Brain damage resulting is massive Fronto - temporo -parietal lesion Complete occlusion of MCA Rarely without hemiplegia

Transcortical motor aphasia:

Transcortical motor aphasia Similarities to motor aphasia But with intact repetition Lesion in the border zone Superior or anterior to broca’s area Non-fluent Limited speech output Auditory comprehension-good Reading comprehension –good Syntax not as bad as in broca’s aphasia Occlusion of anterior cerebral artery

Transcortical sensory aphasia:

Transcortical sensory aphasia Similarities to sensory aphasia But with intact repetition Deficits in all lang. modalities Fluent aphasia Echolalia They can repeat; but cant understand it Much difficulty in communicating Syntax not as bad as in Broca’s aphasia Lesion in the border zone Posterior and inferior to Wernicke’s area Occlusion to anterior cerebral artery

RELATED DISORDERS:

RELATED DISORDERS Apraxia –acquired disorder of learned skill affecting sequential motor movements which cant be accounted by elementary disturbances of strength, co-ordination, sensation or comprehension Agnosia -an acquired disorder of recognition in some sensory modality i.e. visual, auditory or tactile It can be objects, pictures, faces, colors Patients with auditory agnosia hear a door bell ring; but doesnot recognise its meaning

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