aphasia – language deficit that cannot be attributed to motor, ... other names – verbal dyspraxia, articulatory apraxia, childood speech apraxia

1. Aphasias & Apraxias
Sidra Akhtar

2. Outline
• Review the relationships between lesions and
linguistic effects
• Review of the traditional picture about Broca’s
aphasia, and agrammatism
• Examine how a particular study arrived at a
more detailed picture of the deficit in Broca’s
aphasia

3. Cortical Regions
Although we have seen large scale brain
structures (e.g. lobes), Damasio refers to
cortical regions by number in the reading.
Pink: Frontal
Blue: Parietal
Green: Temporal
Yellow: Occipital

4. Brodmann Areas
Distinct brain areas identified in terms of anatomical structure
•So e.g. Broca’s area is
sometimes defined
as consisting of 44,45;
much of the literature
uses these numbers
because of their precise
definitions.

5. Traditional Distinction
• Broca’s: Non-fluent
speech; function words
and morphemes
omitted;
comprehension ok.
• Wernicke’s: Fluent
speech, but filled with
non-sense or filler
words; comprehension
impaired.
From a traditional point of view:

6. Areas and Connections
Broca
Wernicke
Arcuate Fascisculus

7. Causes
• Stroke
• Head injury
• Tumors
• Degenerative conditions (e.g. Alzheimer’s)

8. Types
• Broca’s (more later)
• Wernicke’s: Damage to posterior area
• Conduction: Arcuate + cortex above
• Global: Entire set of language areas

9. Wernicke’s
Speech: Fluent and well-articulated; but
contains many non-words, or filler words
Comprehension: Poor
Basic Idea: Damage to areas in which
words are stored, or in which the phono-
logical forms of words are associated
with meanings.

10. Conduction Aphasia
Lesion: Affects areas connecting Wernicke’s
and Broca’s areas
Supramarginal
gyrus
Also arcuate,
which is underneath

11. Conduction Continued
Speech: Relatively unimpaired; but many
speech errors, or non-words are used. Also
defective naming ability.
Comprehension: Also good, unlike
Wernicke’s, but repetition is not possible
Idea: Network that builds meaningful units
out of speech sounds is disabled.

12. Global Aphasia
Lesion: Covers entire system of language
areas in the dominant hemisphere
Abilities: Almost total inability to produce or
comprehend speech.
Idea: Combines features of Broca’s and
Wernicke’s aphasias

13. Additional Specific Deficits
The Temporal
lobe is shown in
green.
Left temporal pole
Areas 20,21

14. Temporal Lobe Problems
Damage to the temporal pole and areas 20,
21 impairs subjects’ ability to retrieve words.
Other abilities seem to remain more intact.
• Temporal pole alone: proper nouns (John,
Washington, etc.) are affected, not common
nouns like dog, cat, etc.
• Lesion in 20,21: retrieval of both noun types is
severely impaired.

15. APRAXIA

16. Definition
• Exclusionary: The loss of the ability to perform purposeful
skilled movements when this deficit can not be explained by
motor deficits (e.g., weakness), sensory defects, movements
disorders (tremor, ataxia, chorea, athetosis, ballismus,
myoclonus etc) or certain cognitive disorders (e.g., poor
comprehension).
• Inclusionary: There are 5 major types of apraxia and each are
defined by the task demands and types of errors.

17. Types of Limb Apraxia
• 1. Limb-kinetic
• 2. Ideomotor
• 3. Dissociation and Conduction
• 4. Ideational
• 5. Conceptual

18. LIMB-KINETIC APRAXIA
• Testing: 1) pegboard; 2) pincher grasp to pick up small coins; 3)
coin rotation.
• Error Type: Loss of finger deftness or dexterity. Loss of the
ability to perform independent, but coordinated precise finger
movements.
• Pathophysiology: Injury to corticospinal system and/or
convexity premotor cortex. Left hemisphere dominance.

19. IDEOMOTOR APRAXIA
• Testing: 1. Performance of transitive movement to
command (e.g., show me how you would slice bread with a
knife.
2. Imitation of transitive movements.
3. Use of actual tools and implements
4. Discrimination between correct and incorrect
postures and movements.

20. IDEOMOTOR APRAXIA…CON’T
• Error Types
• 1. Postural Errors: a) Incorrect posture; b) Body-part as tool.
• 2. Movement Errors: a) Movement of incorrect join or joints; b)
Poor joint coordination.
• 3. Orientation Error: Not properly directing action toward target.
• 4. Timing-Speed Errors:

21. PATHOPHYSIOLOGY
1. Callosal Lesions
A) Geschwind and Kaplan, right arm normal, left impaired to command
only…possible language disconnection (see Fig.)
B) Watson and Heilman, right arm normal, left arm impaired to
command, imitation, and use of actual objects…disconnection of
movement representations.
2. Left Hemisphere Lesions
A) Asymbolia – apraxia and aphasia can be dissociated
B) Geschwind Intrahemispheric disconnection-cannot explain impaired
imitation and actual object use (see Fig).
C) Heilman-Rothi- lateralized movement representations in left parietal
lobe (see Fig).

22. Conceptual Apraxia
• Definition: A loss of mechanical knowledge, such that a patient
cannot select the proper tools to perform a tasks, or does not
understand the mechanical advantage offered by tools.

23. Conceptual Apraxia Continued
• Testing:
• 1) Tool Selection (e.g., Patient is shown incomplete task, such a partially
driven in nail and tools such as a hammer, screwdriver, hand saw, wrench,
and can opener. The patient is asked to point to the tool need to complete
the task.
• 2) Alternate Tools (e.g., The hammer is taken away and the patient is asked,
“What tool would you use now?”
• 3) Developing Tools (e.g., The patient is shown a wooden block with an eye
hook on top which is sitting on the bottom of a plexiglass tube. The patient
is given a wire and asked to retrieve block. The patient needs to make
hook.)

24. Conceptual Apraxia Continued
• Errors: Inability to correctly perform the tests
mentioned above.
• Pathophysiology: Loss of action-tool semantics. In the
right handed people this knowledge is stored in the
left hemisphere and functional imaging suggests that
the left parietal lobe might also be important for
storing these representations.

25. Dissociation Apraxia
• Definition: Inability to perform correct pantomimes to a
modality specific stimulus.
• Testing: Pantomime to command, seeing tool or object, feeling
tool or object and imitation.
• Error Types: Failure in one modality (e.g.,command), but
normal performance in other modalities (e.g., seeing tool.)
• Pathophysiology: Disconnection of intact movement
representations from modality specific input (see figure).

26. Ideational Apraxia
• Definition: Loss of the ability to order a series of acts to
achieve a goal.
• Testing: Present patient with items needed to complete a task
such as making a sandwich (bread, lettuce, tomatoes, cheese,
mayo, ham, and a knife). The ask patient to make sandwich.
• Errors: Patient makes errors in ordering a series of acts (e.g.,
cuts bread in half before putting on the ham etc.
• Pathophysiology: Not fully investigated