apraxia: neuropsychological- information processing models kenneth m. heilman m.d. the james e....
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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
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.
Types of Limb Apraxia
• 1. Limb-kinetic
• 2. Ideomotor
• 3. Dissociation and Conduction
• 4. Ideational
• 5. Conceptual
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.
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.
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:
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).
CALLOSAL APRAXIA-VERBAL DISCONNECTION
Lexical-Sematics
MC
PMC
SSC
VCVAA
LT RT
Geschwind’s Model of Ideomotor Apraxia
Auditory cortex
Wernicke’s area
LeftPremotor
Cortex
LeftMotorCortex
RightPremotor
Cortex
RightMotorCortex
Heilman-Rothi Model
Lexicon
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
MotorCortex
ObjectRecognition
Units
IDEOMOTOR APRAXIA
Lexicon
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
LTMOTORCORTEX
ObjectRecognition
Units
RTMOTORCORTEX
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.
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.)
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.
Conceptual Apraxia
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
MotorCortex
ObjectRecognition
Units
Action-ToolSemantics
Lexical Semantics
Motor Neurons
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).
Dissociation Apraxia
LexicalSemantics
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
MotorCortex
ObjectRecognition
Units
Dissociation and Conduction Apraxias:A=Verbal dissociation apraxia; B= Visual dissociation apraxia;;
C=Conduction apraxia ;
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
MotorCortex
ObjectRecognition
Units
Action-ToolSemantics
Lexical Semantics
Verbal command
View toolVisual Ass’nCortex
V5View Pantomime
A
B
C
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
PRAXIS SYSTEMS
CORPUS CALLOSUM
OBJECTUNITS
MO
TO
R C
OR
TE
XM
OT
OR
CO
RT
EX
PREMOTORCOREX
MOVEMENTREPRESENTATIONS
ACTIONSEMANTICS
LEXICAL-SEMANTICS
PREMOTOR CORTEX
Auditory input
Visual input
To spinal cord
To spinal cord
Right Hemisphere
Visual gesture input
SUMMARY:a=dissociation apraxia; b=conceptual apraxia;
c=ideomotor apraxia; d=limb-kinetic apraxia; e = conduction apraxia
MovementFormula
SMAPremotor
Cortex
ConvexityPremotor
Cortex
MotorCortex Object
RecognitionUnits
Action-ToolSemantics
Lexical -Semantics
a
a
b
c
c
c
d
dd
V-5
e