Apraxia & Neglect
apraxias and neglect
Apraxia
- An inability to perform a purposeful action in the setting of preserved overall neurologic function.
- It is more common with left brain injuries.
Neglect
- Is a lack of regard for objects in the contralateral hemisphere.
- It's more common with right brain injuries.
Apraxia
Key Landmarks: We use a left lateral hemisphere.
- For reference, include the following sulci:
- Central sulcus
- Precentral sulcus
- Intraparietal sulcus
Frontally-based executive apraxias
- Affect movement
Posterior apraxias
- Affect sensory skills & sensorimotor planning.
The executive apraxias
Limb-kinetic apraxia
- Limb-kinetic apraxia occurs from injury to the premotor area.
In limb-kinetic apraxia, there is impairment in finely graded finger movements and awkwardness of the arm and hand, manifesting with an inability to rhythmically open and close the affected hand.
Speech apraxia
- In speech apraxia (which is a slowing and incoordination of speech in the presence of otherwise normal language and sound vocalization) there is injury to what is referred to in this context as the left precentral gyrus of the insula.
The posterior apraxias
Ideational apraxia
- Ideational apraxia occurs from left hemispheric temporoparietal junction injury.
- By at least one accepted definition, ideational apraxia is an inability to correctly conceptualize an action but variations in the definitions of ideational and ideomotor apraxia exist.
- For instance, patients with ideational apraxia might brush their teeth with a spoon or may be unable to sequence a complex action, meaning, for instance, rather than putting a letter into an envelope and sealing it, they might seal the envelope and then try to stuff the letter into it.
Ideomotor apraxia
- Ideomotor apraxia occurs from injury to the left inferior parietal lobule (supramarginal gyrus & angular gyrus).
- Note that ideomotor apraxia also occurs through disconnection phenomena from injury to the premotor cortex and anterior corpus callosum.
- Ideomotor apraxia is a failure to know how to perform a complex motor movement; gestures, such as waving goodbye, are more severely affected than concrete movements, such as using an actual tool.
Optic ataxia
- Optic ataxia (aka visuomotor ataxia) occurs from injury to the superior parietal lobule (although it's argued that the actual lesion site for optic ataxia may lie more inferoposterior at the parieto-occipital junction).
- Optic ataxia manifests with an inability to accurately reach for objects due to visual guidance impairment.
- Optic ataxia is one of three important features of Balint syndrome, which is due to bilateral occipitoparietal lesions.
Balint Syndrome
- Optic ataxia
- Gaze apraxia (aka oculomotor apraxia or optic apraxia)
- An inability to direct the eyes toward the intended target (instead the eyes fixate on random objects or wander aimlessly)
- Simultagnosia
- The visual fixation on a part of an object and an inability to see the object for its whole.
Gerstmann syndrome
- Gerstmann syndrome occurs from injury to the left hemispheric inferior parietal lobule with specific involvement of the angular gyrus.
It is a four-part syndrome of
- Left–right disorientation
- Finger agnosia, which is a finger naming disorder
- Dyscalculia, which is a calculation disorder
- Dysgraphia, which is a writing disorder.
hemispatial neglect
- May be as mild as to cause extinction to double simultaneous stimulation, meaning that patients will perceive a sensory stimulus on the left side when it is presented only to that side and neglect the stimulus when it is presented to both sides.
- Or it may be as severe as to cause failure to attend to the left half of the world, entirely.
- Large right parietal lobe injuries can cause anosognosia, which is a lack of awareness of the presence of a deficit.
- When anosognosia accompanies occipital lobe injury, which results in a visual field deficit, patients may display a denial of their own blindness, called Anton syndrome.
Autotopagnosia
- In a separate form of lack of awareness, patients may demonstrate autotopagnosia, which manifests with an unawareness of one's own body parts.
- For instance, in right hemispheric strokes with hemispatial neglect, patients with autotopagnosia may insist that their left hand is not their own but is instead the examiner's hand.