APRAXIA: Neuropsychological-Information Processing Models

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APRAXIA Neuropsychological-Information
Processing Models

• Kenneth M. Heilman M.D.
• The James E. Rooks Jr. Distinguished Professor of
  Neurology, University of Florida, College of
  Medicine

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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.

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Types of Limb Apraxia

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

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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.

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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.

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IDEOMOTOR APRAXIACONT

• 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

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PATHOPHYSIOLOGY

• 1. Callosal Lesions
• A) Geschwind and Kaplan, right arm normal,
  left impaired to command onlypossible language
  disconnection (see Fig.)?
• B) Watson and Heilman, right arm normal,
  left arm impaired to command, imitation, and use
  of actual objectsdisconnection 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).

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CALLOSAL APRAXIA-VERBAL DISCONNECTION
LT RT
PMC
MC
SSC
Lexical- Sematics
VAA
VC
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Geschwinds Model of Ideomotor Apraxia
Right Premotor Cortex
Right Motor Cortex
Wernickes area
Left Motor Cortex
Left Premotor Cortex
Auditory cortex
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Heilman-Rothi Model
SMA Premotor Cortex
Object Recognition Units
Motor Cortex
Movement Formula
Convexity Premotor Cortex
Lexicon
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IDEOMOTOR APRAXIA
RT MOTOR CORTEX
SMA Premotor Cortex
Object Recognition Units
LT MOTOR CORTEX
Movement Formula
Convexity Premotor Cortex
Lexicon
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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.

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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.)?

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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.

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Conceptual Apraxia
Lexical Semantics
Action-Tool Semantics
SMA Premotor Cortex
Motor Cortex
Movement Formula
Object Recognition Units
Convexity Premotor Cortex
Motor Neurons
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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).

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Dissociation Apraxia
SMA Premotor Cortex
Object Recognition Units
Motor Cortex
Movement Formula
Convexity Premotor Cortex
Lexical Semantics
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Dissociation and Conduction ApraxiasAVerbal
dissociation apraxia B Visual dissociation
apraxia CConduction apraxia
Lexical Semantics
Action-Tool Semantics
A
SMA Premotor Cortex
Motor Cortex
Verbal command
B
Movement Formula
Object Recognition Units
Convexity Premotor Cortex
Visual Assn Cortex V5
View tool
C
View Pantomime
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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

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PRAXIS SYSTEMS
To spinal cord
MOTOR CORTEX
Right Hemisphere
PREMOTOR CORTEX
CORPUS CALLOSUM
OBJECT UNITS
ACTION SEMANTICS
Visual input
PREMOTOR COREX
MOVEMENT REPRESENTATIONS
MOTOR CORTEX
Visual gesture input
LEXICAL- SEMANTICS
Auditory input
To spinal cord
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SUMMARYadissociation apraxia bconceptual
apraxia cideomotor apraxia dlimb-kinetic
apraxia e conduction apraxia
Lexical - Semantics
b
Action-Tool Semantics
c
SMA Premotor Cortex
a
Motor Cortex
c
Object Recognition Units
a
Movement Formula
Convexity Premotor Cortex
d
d
c
d
V-5
e