Apraxia Flashcards
Apraxia
- A disorder of learned movement
- Problem in the organisation of actions
- Not accounted for by deficits in coordination, weakness, incomprehension etc.
Apraxia (damage to corpus collosum)
• Can carry commands with the right arm,
ex: show me how you comb your hair…
• Comprehension intact
• But with the left arm… incorrect
• Can do those tasks in normal life (ex: use tools, combs, etc) or imitate the gestures
• Can do face movements if asked like blow a candel
• The face area of the motor cortex can control the
cranial muscles on both sides
• The left cortical face area does it
Apraxia (damage to the left premotor region)
• Lesion affecting an area including motor area and Broca
-if large lesion: paralysis of the right limbs
• Cannot carry out facial movements
• Information from the left Wernicke’s area cannot reach
the left premotor region because it is destroyed
• The lesion also destroyed the callosal fibers connecting
L premotor cortex from the R PMC
→ facial apraxia
Apraxia (damage in the connections between Wernicke and the premotor area)
- Intrahemispheric
- Also show conduction aphasia
- If lesion not near the precentral motor cortex: no paralysis
- Patient unable to carry movement with the right limbs or the left limbs because if the info does not reach the left motor area, can’t be transferd to the right by the CC
- Also facial apraxia
Apraxia (lesion to Wernicke’s area)
- Patient fail to respond to verbal command
- Deficit in comprehension
- Not apraxia
Apraxia (lesion in the left parietal operculum)
• Normal comprehension
• Difficulty to execute verbal commands with both left and right limbs, or face
• Axial movement ok, ex: bow, kneel etc…
Explanation: the pyramidal system
• Motor pathway from the precentral gyrus
The Descending Tracts
Pyramidal tract
- Voluntary movement and control of the musculature of the opposite side of the body
About 90% decussate: control of limbs
→Lateral corticospinal tract
About 10%: do not decussate at the pyramids, they
continue ipsilateral: control of trunk, neck etc.
→Anterior corticospinal tract
Also input from other cortical areas than the motor cortex
Anterior corticospinal tract
- not entirely contralateral because movements of the body trunk involve both sides of the body.
- By influencing of both sides of the body, can coordinate postural muscles in broad movements of the body.
- These coordinating axons are often considered bilateral, as they are both ipsilateral and contralateral.
Axial Control
- The anterior corticospinal tract: responsible for controlling the muscles of the body trunk.
- These axons do not decussate in the medulla.
- They remain in an anterior position as they descend the brain stem and enter the spinal cord.
- Upon reaching the appropriate level in the spinal cord, the axons decussate, entering the ventral horn on the opposite side of the spinal cord from which they entered.
- In the ventral horn, these axons synapse with their corresponding lower motor neurons.
- The lower motor neurons are located in the medial regions of the ventral horn, because they control the axial muscles of the trunk.
Ideational apraxia
• Alterations of the mental representation of the action to
accomplish
• Affects complex gestures, the more complex the sequence the harder
• When manipulation of tools is needed
• Affects both spontaneous and on command gestures
• The basic gestures are ok but the meaning of it is incoherent
• Patient seems like he doesn’t remember the use of objects
• The components of the acts are there but not in the right order: the sequence
of movement is lost
• Lesions most often temporo-parieto-occipital junction: more extensive
• Semantic information
Ideomotor apraxia
• Alteration in the transmission between the ideation and the motor gesture: the motor project not transmitted to the parts to make it
• Deficits even in elementary gestures
• Difficult production of movements
• Hard to imitate or act in response to a command
• Use of body part as object
• But correct execution when needed in real life context
• Can name, describe and understand the gesture the examiner is making but cannot
reproduce it
• Difficulties in the planning of the gesture while the mental conception is intact
• Most often parietal lesion
• Lesion disconnecting left auditory (or visual) from motor areas
• If unilateral left apraxia: RH lesion or Corpus callosum
Sympatehic Apraxia
• A type of ideomotor apraxia
• Posterior language comprehension area is intact
• Lesion around the left inferior frontal area
• R arm paralysed
• L arm apraxic: Right motor cortex is intact so the L
arm can move but a command is not received
from the L motor cortex through the CC
• Left hemisphere dominance for skilled movement (in
right handed)
Dressing Apraxia
• Automatic, spontaneous capacity for dressing is lost
• Parietal right lesions: incapacity of effectuating the acts of dressing correctly, sequence, what to put
where…
• Parietal lesions of the left hemisphere: dressing apraxia appears to be more related to general deficits
of planning of gestures with both limbs.
• Not the same as personal hemineglect!
Apraxia of gait
• A motor planning deficit
• Patients with gait apraxia have a hard time getting started with walking and may have a Gait apraxia is
commonly seen in dementia (especially vascular dementia).
• No motor weakness
• Disorder of locomotion characterized by inability in lifting the feet from the floor despite alternating
stepping action (frozen gait), and disequilibrium.
• Responsible site of lesions are in the frontal lobe, dorsomedial frontal cortex, SMA region or immediately
subjacent white matter
• and/or the basal ganglia
• Gait recruits a complex network
• It is observed in an advanced stage of Parkinson’
Constructional Apraxia
• Inability to understand spatial relationship between objects
• Ex: reconstruct a puzzle or reproduce a model with blocks
• Parietal lobe lesions
• Mostly Right, also left
Reminder: the right hemisphere is better for spatial construction, orientation, distributing our attention in space
