Limb Apraxia

 

Disorder of skilled movement, not caused by weakness, ataxia, akinesia, deafferentation, inattention, or poor comprehension. Reflects disrupted higher processing btwn perception, cognition, and action.

 

Types:

- dressing apraxia - rt parietal

            E.g. Storkes, neurodegenerative

- oculomotor apraxia - (head thrust) bilat sup parietal

            E.g. AT, bilat strokes, CBD

- verbal apraxia - inf frontal

            E.g. CBD

- oral apraxia - inf frontal

            May not be with verbal apraxia

- gait apraxia - bifrontal

            Magnetic gait, e.g., NPH

- limb apraxia - ideomotor, ideation, conceptual, callosal

 

Limb apraxia:

- stroke

- alzheimer

- CBD

- primary progressive aphasia

- PD

- PSP

 

1. Sensory/perceptual system

2. Conceptual system

3. Production system

 

Praxis control

- visual - bilat occipital

- knowledge of tool fcn - left sup temp gyrus

- comprehension - left Wernicke

- praxis control - ?supramarginal gyrus ?premotor, predominantly left

- output control - sensorimotor strip

 

Rt hemisphere can also be involved, unclear where

 

Anterior corpus callosum more crossing of this motor activity than posterior.

 

Testing

 

1. Gesture and tool recognition

- naming

- identification

 

2. Gesture recognition

 

3. Movement production

- pantomime - harder in left hemisphere damage

- imitation

 

Scoring system

- location

- posture

- action

- plane

- orientation

- object use

 

Diseases:

Stroke

Ideomotor worse than ideation in early alzheimer.

CBD - characteristic

Primary progressive aphasia

 

Alexia

 

Printed word to speech

Lt angular gyrus - alexia & agraphia

Pure alexia is caused by damage of left inferior occipital-temporal and splenium of corpus callosum

More trouble with long words (they spell out words to read).

 

Visual agnosia

 

- object agnosia

            - apperceptive

            - associative

- facial agnosia - prosopagnosia

- spatial agnosia

- word agnosia - pure alexia

 

Superior occipital-parietal system for spatial localization. (where) - visuospatial neglect

Inferior occipital temporal region for visual object recognition. (what) - visual agnosia

This is usually more bilateral.

 

Neglect

 

 Rt hemisphere syndromes

- neglect

- visuoconstructive /  visuoperceptual problems

- aprosodia / emotional indifference

- social cognition / self-monitoring

 

Failure to orient to or respond to or be aware of the side opposite to damaged side.

 

1. Multimodal

2. Spatial coordinates

            - Personal

            - Peripersonal

            - Extrapersonal

            - Representational

3. A. Attentional

    B. Intentional

            - limb akinesia/hypokinesia, motor extinction, hemispatial akinesia, directional hypokinesia

4. Reference system

            - hemispace / hemifield

            - contralateral / contralesional

            - viewer centered (egocentric)

            - object centered (allocentric)

            - environmental centered (allocentric)

            - on body - somatotopic vs environmental

5. Sensory phenomena

            - extinction

            - allesthesia - mislocalize

6. Hypoarousal

7. Denial of illness - anosognosia

8. Denial of body part, somatic delusions (asomatagnosia - somatoparaphrenia)

9. Unconscious processing

            - still influenced by unperceived stimuli

10. Effects of complexity

            - top-down processing

            - neglect alexia - word vs. nonwords