Apraxia Flashcards
Ideational apraxia
Failure to perform sequential motor movements though each individual component can be performed in isolation
Neuroanatomical correlate of ideational apraxia
L parietal lobe or diffuse cortical involvement (dementia)
Conduction apraxia
Pt can pantomime movements to command, but has difficulty imitating transitive movements
Four broad categories of errors seen in ideomotor apraxia
1) perseverative 2) sequencing error 3) spatial 4) timing
Neuroanatomical correlate of ideomotor apraxia
LH, anywhere w/i perisylvian region
Limb-kinetic apraxia
Loss of deftness including ability to make finely graded, precise, individual but coordinated finger movements
According to the ideomotor apraxia model, lesions of the left inferior parietal lobe will lead to
Inability to recognize gestures b/c damage to representations of learned, skilled mvmts; gesture discrimination problem
What are innervatory patterns (in relation to apraxia)?
Heilman’s theory: the specific motor plan used for praxis. The supplementary motor cortex is responsible for translating praxicons into innervatory patterns.
Weintraub says that ideational apraxia may represent a primary distrubance of
Attention or executive functions
2 causes of ideomotor apraxia, as postulated by the representational hypothesis
Damage to the praxicons (believed to be in either L supramarginal or angular gyrus) OR connection b/t this area & primary motor cortex
Patients with ideomotor apraxia have the greatest difficulties when asked to make what type of movements?
Transative (to use a tool) However, is also seen with intransitive movements
Dressing apraxia
Difficulty with dressing following RH lesions; not seen in isolation
Ocular apraxia
Inability to perform purposeful ocular movements Component of Balint’s syndrome
Ideomotor apraxia
Defective execution of individual components of an action
Conceptual apraxia
Pt can make transitive movements, but use the wrong one (ex hammering motor for screwdriver) Assoc. w/ posterior L lesions (Liepman says caudal L parietal)
According to the ideomotor apraxia model, lesions of the connections between the left inferior parietal lobe & the supplementary motor area will lead to
Bilateral ideomotor apraxia but can comprehend & discriminate gestures; movement memories not destroyed, just can’t interact with anterior areas responsible for motor implementation
Buccofacial apraxia
Difficulty making movements with face, larynx, pharynx, etc. Assoc. w/ lesions in frontal & central opercula, anterior insula, 1st temporal gyrus
According to the ideomotor apraxia model, lesions of the supplementary motor area will lead to
Bilateral ideomotor apraxia with an inability to comprehend & discriminate gestures; innervatory patterns can’t gait access to motor area
Optic apraxia/optic ataxia
Apraxia of ocular searching movements affecting visually-guided hand mvmt
Gait apraxia
Disorder of gait seen in diseases affecting the frontal lobe
3 types of spatial errors seen in ideomotor apraxia
1) posture 2) spatial orientation 3) spatial movement (movement at wrong joints)
Disconnection hypothesis of apraxia
Disconnection b/t language areas & visuokinesthetic engrams; fibers either cross from Wernicke’s area to the CL association area or from the L premotor area to the R premotor area
Ansher & Benson (1993) - potential sites of damage associated with apraxia
- Lesion to L parietal lobe can damage arcuate fasciculus, interrupting flow of into anteriorly, prevents motor system from receiving direction to act
- Large lesion to L premotor area interferes w/ motor execution
- Lesion to anterior CC (only seen w/ L hand)
Goodglass defective symbolization model of apraxia
Because the LH seems involved in both apraxia & aphasia, this is the idea that the L is involved in symbolization (apraxia being a loss of nonverbal symbolization). Counter argument: not all individuals with apraxia have aphasia
Representational (or praxicon) hypothesis of apraxia
Heilman argues for existence of ‘visuo-kinesthetic engrams’ or ‘praxiconx’ in the inferior parietal lobe
Based on idea that newrvous system learns & stores skilled mvmt; disconnection b/t the area that stores this info & premotor/motor areas will result in poor implementation of skill mvmts
Buccofacial apraxia is common with type of aphasia?
Broca’s
Neuroanatomical correlate of limb-kinetic apraxia
CL premotor area or subjacent WM
Liepman’s neuroanatomical model of apraxia
Suggested that the L parietal area is critical for control of complex mvmt; mediated by the L frontal lobe & area 4 for the R side of the body; disruption anywhere in this system would produce R-sided apraxia; control of the L limbs was proposed to be mediated via CC
Proglems with Liepman’s Neuroanatomical Model
Does not recognize involvement of BG & thalamus in movement
Patients w/ circumscribed cortical lesions do not typically demonstrate chronic abnormalities on standard clinical tests of apraxia
Geschwind’s model of apraxia involves impairment of what tract?
Arcuate fasciculus
Apraxia
Acquired disorder of skilled purposeful movement (may still do automatically)
Representational hypothesis of apraxia (Heilman)
The brain stores “praxicons” (visuo-kinesthetic engrams) in the inferior parietal lobe
