01- clinical aspects of language disorder · korean brain mapping & plasticity research group...

KOREAN BRAIN MAPPING & PLASTICITY RESEARCH GROUPKOREAN BRAIN MAPPING & PLASTICITY RESEARCH GROUP

Clinical Aspect of Language Disorder

Yun-Hee Kim, MD, PhDDepartment of Physical Medicine & Rehabilitation

College of Medicine Sungkyunkwan University Samsung Medical Center


Facets of Language

Vehicle for communication of information

Medium for artistic expression

Method of expression of emotion

Means for developing thought


Language Processing

Input AuditionVisionSomesthesis

Output SpeechSignsWritingsBrailleGestures

Interconnecting linguistic processingEmotional coloring

Feedback-looping


Spoken input Written inputAcoustic phonetic analysis Visual orthographic

analysisPhonetic features phonemes

syllablesAuditory lexicon

Phonological forms of words

Semantic access

Visual Lexicon

Orthographic forms of words

Semantic access

Phonological lexiconOrthographic lexicon

Orthographic forms of words

Orthographic planning

Letter sequences

Written output planning

Manual movements

Phonological forms of wordsPhonological output

planning

Phonetic features

Articulatory planning

Articulatory gestures

Lexical phonology → Orthography

Lexical orthography → Phonology

Sublexical phonology → Orthography

Sublexical orthography → Phonology

Word meaningsComprehension

Production

Caplan’s Diagram for Language Processing: Simple words


Language Comprehension

Spoken name Wernicke’s area (auditory memory)

Angular gyrus

(visual memory)

Visual image Angular gyrus

(visual memory)

Wernicke’s area (auditory memory)


Language ProductionBroca’s area :

Program for the control of precentral face area and supplementary motor areaLearned rule for converting auditory pattern into spoken form

Spoken name Wernicke’s area

Transmission of neural pattern through arcuate fasciculus

Broca’s area

Visual image Angular gyrus

Transmission of neural pattern through arcuate fasciculus

Broca’s area

Wernicke’s area


Cortical Language Areas by Electrical Stimulation of Cortex

Penfield and Roberts, 1958

Left RightBasal temporal language areaLuders et al, Epilepsia, 1988


Connecting Fibers for Language Processing

Commisural fibers: callosal fiberAssociation fibers:

Superior longitudinal fasciculus (arcuate fasciculus)Superior occipitofrontal fasciculusInferior occipitofrontal fasciculusInferior longitudinal fasciculusShort association fibers

Projection fiber:Corticothalamic fiber


Fronto-Temporal Connections

Uncinate fasciculus

Arcuate fasciculus

Wise, Br Med Bull, 2003

To ventral and rostralPFC; process word meaning

To dorsolateral PFC; process word sound structure (Phonetics and phonology)


Language Play-Back Loop

Two sectors in Broca’sarea

posterior -> SMAanterior -> auditory association area

Comparison of language production with language perceptionConnectivity based working memory for language decoding and encoding


Clinical Language Disorders

Aphasia syndromeDevelopmental language disorderPrimary progressive aphasia


22/M with cortical dysplasia: Verb generation vs. rest (Kim, 1998)

LR

Plasticity of Language System


Mimura et. al. 1998, Brain20 aphasic patients within first year after stroke and 16 aphasic patients 7 years after stroke using SPECTInitial language recovery: primarily by the dominant hemisphereLong term recovery: slow and gradual, increased blood flow in the contralateral hemisphere, especially in the homotopic frontal and thalamic areas

Functional Imaging Studies of Language in Aphasia


Thulborn et al, Stroke, 1999

•Activation of right hemisphere after stroke in 2 aphasic patients using fMRI, in a Broca homologous area.•Rightward activation appeared early and continued

Broca’s aphasiaWernike’s aphasia

Plasticity of Language-Related Brain Function during Recovery from Stroke


6 aphasic patients with left IFG lesionWord stem-completion taskActivation of right IFG for performing language task

Rosen et al, Neurology, 2000

Neural Correlates of Recovery from Aphasia after Damage to Left Inferior Frontal Cortex

L R


Activation during word generation: Functional correlation of right frontal activity


12 aphasic patients using FDG PETWithin 4 wks of stroke, and follow up after I year(7 pts.)

Two strategies to recover from post-stroke aphasiaStructural repair of primarily speech-relevant regionsActivation of compensatory areasSMA: most prominent compensatory activation in the subacute stageRestitution of the left STC determine the long-term prognosisRight hemisphere compensation was less effective than the repair of original speech network

Karbe et al, Brain and Language, 1998

Brain Plasticity in Poststroke Aphasia: What is the Contribution of the Right Hemisphere?


Relation between Accuracy of Token Test and Regional Activation

One year follow up


Frontal Laterality Index in Aphasic Patients

Cortical

Cortical

Cortical

Subcortical

Cortical

Cortical

Cortical

Cortical

Subcortical

Subcortical

Cortical

Cortical

Cortical

Subcortical

Subcortical

Cortical

Subcortical

Aphasia Type

0.20 93.5%8.5F/15Lt. MCA infarction13

0.12 66.6%37M/64HICH on Lt. B.G.14

0.08 68.5%8M/41Lt. MCA infarction15

-0.10 63.3%3.5M/36Lt. T-P infarction16

49.5M/48

F/54

M/65

F/44

F/58

M/35

M/41

M/62

M/65

M/62

M/53

M/49

M/48

Sex/Age

-1.00 10.4%5.5Cbr. Infarction17-0.2062.0%17.1Mean

24

2.5

4.5

3

29

72.5

8

8

2.5

32

29.5

13

POD (months)

0.01 55.7%Lt. MCA infarction12

-1.00 53.3%Multi-infarct, Lt F, Rt. T 11

-0.41 27.1%Lt. MCA infarction10

-0.64 93.0%HICH on Lt. B.G.9

0.27 95.7%HICH on Lt. B.G.8

0.18 42.9%Lt. MCA infarction7

-0.12 75.4%ICH on Lt. P-O6


-0.34 72.0%ICH on Lt. B.G.4

-0.41 52.0%HICH on Lt. B.G.3


0.25 78.1%HICH on Lt. B.G.1

Laterality In.PerformanceLesionPatient

Kim et al, 2002


Comparison by Postonset Duration

-0.01

65.1%

4

6 months ~1 year

0.01*-0. 58 Laterality Index

68.1%53.2%Language Performance

76Number of Patient

Above 1 yearWithin 6 msPostonset Duration

* p < .05


Aphasia Treatment: Changes of Laterality Index in Chronic Aphasics after Rehabilitation

41.8 months24.3 monthsPOD (mean)

0.17*-0.09Laterality Index

74.3%*65.2%Lang. Performance

8Number of Patient

F/U fMRI1st fMRIComparison of Pre and Post Study

* p < .05


Differential Capacity of Left and Right Hemispheric Areas for Compensation of Poststroke Aphasia

23 right-handed aphasic patients, 7 frontal, 9 subcortical, 7 temporalH215O PETWord repetition task2 and 8 weeks after strokePoorest outcome in temporal group

Heiss et al, Ann Neurol, 1999

Frontal lesionFrontal lesion

Subcortical lesionSubcortical lesion

Temporal lesionTemporal lesion


Hierarchy within the Language-Related Network

Effectiveness of improvement of aphasiaRight hemispheric area contribute if left hemispheric lesions destroyedEfficient restoration of language is usually only achieved if left temporal areas are preserved and can be integrated into the functional network


20 patients with Wernick’s aphasia (42-70 yrs.)Language comprehension training4 patients (55-60 yrs.) – PETLanguage comprehension task

Training-Induced Brain Plasticity in Aphasia

Musso et al, 2002


Neural Correlates of Aphasia Treatment


Leger et al, Neuroimage, 2002

Neural Substrates of Spoken Language Rehabilitation


Effect of Combined Medication and Speech Therapy:Use of Amphetamine in the Treatment of Aphasia

Walker-Batson et. al., Stroke, 2001


24 stroke patients12 piracetam, 12 placebo6-wk intensive speech therapyH215O PET before and after therapyWord repetition taskImproved language performance and blood flow in language relevant areas

Kessler et al, Stroke, 2000

Effect of Combined Medication and Speech Therapy:iracetam Improves Activated Blood Flow and Facilitates

Rehabilitation of Poststroke Aphasic Patients


Factors Influencing on Reorganization and Language Recovery

Severity of language area damageLesion locationTiming and type of rehabilitationMedications

DopaminergicCholinergic

Further development of various rehabilitation methodologies to maximize brain plasticityshould be encouraged


~ 7 % of childrenAbsence of mental retardetion, deafness, neurological deficit or social deprevationGenetic or familial predispositionNeuroanatomical correlation:

Planum temporaleBroca’s area and adjacent sulcal morphologyCaudate neucleusCorpus callosum

c.f. Language regression in childhoodAutistic regressionAcquired epileptic aphasia (Landau-Kleffner syndrome)

Developmental Disorders of Speech and Language

Watkins et al, Brain, 2002Fabbro et al, Neuropsychologia, 2002


Persistent Developmental Stuttering

Developmental stutteringCompromised complex system interacting between speech and languageInvoluntary repetition, lengthened sounds, or arrest of sounds4-5% of 3-5 y-o childrenImpairments persists after puberty in 1% of people (men> women)Genetic basis

PathophysiologyAbnormal patterns of cerebral hemispheric dominanceShift of activation to the right hemisphereImpaired oral motor controlImpaired auditory self-monitoring of speechSynchronization deficit in speech preparation and execution


Disconnection of Speech Relevant Areas in Persistent Developmental Stuttering

Cortical disconnection immediately below the laryngeal and tongue representation in the left sensorimotor cortex (Rolandicoperculum)

Relative FA reduction (32.8%, p=0.014 corrected) in stutter group than controls Sommer et al, Lancet, 2002


Primary Progressive Aphasia (PPA)A Language-Based Dementia

Inciduous onset, gradual but progressive impairment of word finding, object naming, syntax, or word comprehensionAll major limitation of ADL can be attributed to the language impairment for at least two years after onsetPremorbid language function is known to be intactProminent apathy, disinhibition, loss of memory, visuospatialimpairment, visual-recognition deficit, sensorimotorimpairment are absent during the initial 2 years of illnessAcalculia and idiomotor apraxia can be present even in the first 2 years of illness but neither visuospatial deficit nor behavioral dysinhibition substantially limits ADLOther cognitive functions may be affected after the first two years of illness, but language remains the most impaired function throughout the course of illnessSpecific causes of aphasia, such as stroke or tumor, as ascertained by neuroimaging, are absent

Mesulam, N Engl J Med, 2003


Pathologic Changes of Left Perisylvian Area in PPA

Atrophy in the parietal operculum, the insula, middle, and inferior temporal gyri of the left hemisphere

Decreased blood flow in the early stage of disease


Axonal Injury within Language Network in PPA

Catani et al., Ann Neurol, 2003

Asymmetrical N-acetylaspartate/creatine ratio reduction in the PPA group (L>R) compared with Alzheimer’s disease and controls in the central portion of the SLF


Conclusions

Language is a unique channel of exploring the human brain function.Brain-language network has remarkable plasticity, however, classical left hemispheric language system is the most efficient one. Functional imaging is a powerful technology of investigating pathogenesis of and recovery from various language disorders.

Thank you for your attention!

01- clinical aspects of language disorder · korean brain mapping & plasticity research group...

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