APRAXIA: NeuropsychologicalInformation 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
LT
RT
PMC
MC
SSC
LexicalSematics
VAA
VC
Geschwind’s Model of Ideomotor Apraxia
Right
Premotor
Cortex
Right
Motor
Cortex
Wernicke’s
area
Left
Premotor
Cortex
Left
Motor
Cortex
Auditory
cortex
Heilman-Rothi Model
SMA
Premotor
Cortex
Motor
Cortex
Movement
Formula
Convexity
Premotor
Cortex
Lexicon
Object
Recognition
Units
IDEOMOTOR APRAXIA
RT
MOTOR
CORTEX
SMA
Premotor
Cortex
LT
MOTOR
CORTEX
Movement
Formula
Convexity
Premotor
Cortex
Lexicon
Object
Recognition
Units
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
SMA
Premotor
Cortex
Action-Tool
Semantics
Lexical
Semantics
Movement
Formula
Object
Recognition
Units
Motor
Cortex
Convexity
Premotor
Cortex
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
SMA
Premotor
Cortex
Motor
Cortex
Movement
Formula
Convexity
Premotor
Cortex
Lexical
Semantics
Object
Recognition
Units
Dissociation and Conduction Apraxias:
A=Verbal dissociation apraxia; B= Visual dissociation apraxia;;
C=Conduction apraxia ;
A
SMA
Premotor
Cortex
Motor
Cortex
Convexity
Premotor
Cortex
Lexical
Semantics
Action-Tool
Semantics
B
Movement
Formula
C
Visual Ass’n
Cortex
V5
Verbal command
Object
Recognition
Units
View tool
View Pantomime
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
To spinal cord
PREMOTOR
CORTEX
Right
Hemisphere
CORPUS CALLOSUM
PREMOTOR
COREX
ACTION
SEMANTICS
OBJECT
UNITS
MOVEMENT
REPRESENTATIONS
LEXICALSEMANTICS
Auditory input
To spinal cord
Visual input
Visual gesture input
SUMMARY:
a=dissociation apraxia; b=conceptual apraxia;
c=ideomotor apraxia; d=limb-kinetic apraxia; e = conduction
apraxia
b
c
SMA
Premotor
Cortex
a
c
Motor
Cortex
Convexity
Premotor
Cortex
d
Lexical Semantics
Action-Tool
Semantics
a
d
d
c
Object
Recognition
Units
Movement
Formula
e
V-5