Understanding Aphasias Chairperson - Dr Sanjeev Kumar Presenter - Dr Nikhil Govil
Introduction2 important functions which put humans ahead of other primates is the use of thumb and well developed system of communication(language )in human beingsLanguage- 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 languageLateral surface of brain
Blood supply to speech areas of brainBrocas area and wernickes area are supplied by middle cerebral arteryVisual cortex supplied by posterior cerebral arteryDeep white matter and supplementry cortex supplied by anterior cerebral artery
Lateralization of funcionsLeft hemisphere-Sequential analysisProblem solvinglanguage
Right hemisphere-Simultaneous analysisVisuo-spatial skillEmotional functionsMusic
Pathway of languageWernicke-Geschwind Model1. Repeating a spoken word
Arcuate fasciculus is the bridge from the Wernickes area to the Brocas area
Pathway of language(Contd.)Wernicke-Geschwind Model2. Repeating a written word
Angular gyrus is the gateway from visual cortex to Wernickes area
Definitions pertaining to aphasiaAn 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, writingSyntax(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 )
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 errorsPhonemic: 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 AphasiasIn 1800s Dr Paul Broca was the first to localise the language function in brain. one of his patients could only produce a single syllable tan.Patients autopsy report revealed a lesion in posterior part of the left 3rd frontal convolution which was termed later as brocas areaA language problem distinct from Brocas aphasia was first described by Carl Wernicke (in 1908) which involved Damage to the boundary of the temporal and parietal lobes later termed as wernickes area
Aphasia factsOver 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 factorsUncontrollable factorsAgeGenderRacial or ethnic backgroundFamily historyControllable factorsHypertensionDiabetesTobacco smokingAlcohol use
Causes of aphasiasStroke (most common cause)Degenerative diseases(e.g. parkinsons disease)Head injuryBrain tumorsMultiple sclerosisLandau kleffner syndrome
Causes of aphasia(contd.)Infectious diseases like HSV encephalitisDementias(alzheimers,frontotemporal dementias)Cerebral abscessEpilepsyMigraine
Dissection syndromesPolyarteritis nodosaCerebral venous thrombosisCentral pontine myelinolysisVery rarely seen with fentanyl patches
Types of aphasiasAphasias can be broadly classified in 2 waysFirst on the basis of fluency of speech
Fluent aphasiasNon fluent aphasiasPure aphasiasOn the basis of cause
Fluent aphasias- fluent speech but difficulties either in auditory/ verbal comprehension or in the repetition of words, phrases, or sentences spoken by others
Wernickes aphasiaAnomic aphasiaConduction aphasiaTranscortical sensory aphasia
Types of aphasias (contd.)Non fluent aphasias-difficulties in articulating but relatively good auditory and verbal comprehension
Brocas aphasiaGlobal aphasiaTranscortical motor aphasiaMixed transcortical aphasiaPure aphasias -these are selective impairments in reading, writing, or the recognition of wordsAlexia/pure word blindnessAgraphiaPure word deafnessAlexia 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
Wernickes aphasiaAnterior/receptive/fluent /jargonAbnormal language comprehensionFluent meaningless speechParaphasias errors in producing specific wordsSemantic paraphasias substituting words similar in meaning (barn house)
Phonemic paraphasias substituting words similar in sound (house mouse)
Wernickes aphasia(contd.)Neologisms non words Grammar relatively preservedPoor repetition and namingImpairment in writingAssociated with damage to the temporal lobe near but not including the Heschels gyrus (primary auditory cortex; the patients are not deaf)Occurs as a result of occlusion of inferior division of left middle cerebral arteryNeighborhood signs include superior quadrantanopsia,limb apraxia, finger agnosia, acalculia, agraphia.The patient is usually unaware of his deficit.
Wernickes aphasia speech sampleClinician: Tell me where you live.Patient: Well, its 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: Whats the weather like today?Patient: Fully under the jimjam and on the altigrabber. (Brookshire 2003:155)
Brocas aphasiaExpressive/anterior/non fluent aphasiasNonfluent speech, short phrases,word finding pauses, makes errors in grammar, omits function words (Telegraphic speech)Poor repetition and namingComprehension preserved
Brocas aphasia (contd.)Speech is sparse containing 10-15 words/minute)Can be mild or severeBrocas aphasia is characterised by damage to left 3rd frontal convolution located near inferior frontal gyrusBlockage of superior division of middle cerebral artery
Mainly verb naming deficits i.e. the patient will have difficulty in naming actionsNeighborhood signs include right hemiparesis (face,arm affected more than legs)The patients are aware of their deficit
Brocas aphasia speech sampleExaminer: 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 aphasiaAssociated with extensive left hemisphere damageDeficits in comprehension and production of languageRight hemiplegia(face and arm worse than leg),right homonymous hemianopia is very commonOcclusion of I.C.A/M.C.A
Conduction aphasiasAs explained by the Wernicke-Geschwind model, conduction aphasias occur as a result of damage to the fibres connecting the Brocas and the Wernickes area.Difficulty in repeating what was just heard (no repetition or paraphasias)Comprehension and production intact
Transcortical motor aphasiaTranscortical motor aphasia: Comprehension and repetition are preserved, however, speech is nonfluentDue to Infarction in the watershed area between anterior and middle cerebral atreries in the frontal lobe.
Transcortical sensory aphasiaTranscortical sensory aphasia: Repetition is preserved, speech is fluent but comprehension is impairedDue to Lesion in the parieto-occipital cortex
Mixed transcortical aphasiasAlso called as syndrome of isolation of speech areaRepetition intactPatient can neither comprehend nor able to produce spontaneous speech.
Anomic aphasiaAmnesic /nominal aphasiaComprehension intactFluent speechRepetition is preservedCannot name objects/verbsObject 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 doesYou use it to write on a paper
Pure aphasiasPure 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 aphasiasAgraphia- 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 mu