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Neglect 2


undefined, object
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Neglect: definition
failure to respond to, report, or orient to novel or meaningful stimuli presented to the side opposite the lesion
Neglect: rule outs
sensory, motor, or memory deficits
Neglect: other terms for
unilateral spatial agnosia, amorphosynthesis, left-sided fixed hemianopia, hemi-inattention, hemi-neglect, hemispatial agnosia
Neglect: first description by
jackson (1978)
Sensory neglect: definition
deficit in awareness of stimuli contralateral to a lesion not involving sensory projection systems or primary cortical sensory areas
Neglect: 2 types OR 2 other types
spatial, personal
OR attentional/sensory and intentional/motor
Spatial neglect: 3 frames of reference
body centered, environmentally centered, object centered
Sensory neglect: associated disturbances
inattentive to stimuli ipsilateral to lesion- but this is less severe, problems with disengaging or shifting attention in contralateral direction
Distinguishing sensory neglect from sensory deficit
increasing instructional cues, using novel stimuli, or using strongly motivational cues
Probes for sensory neglect
tests of extinction, line bisection, covert attentional shifts
Sensory-representational neglect: probes for
have pt close eyes and point to body midline, pt usually points to right of midline
Motor-exploratory neglect: definition
reluctance to scan and explore L hemispace
Motor-exploratory neglect: probes
target detection tasks: more difficult tasks are more sensitive in detection (lines easier than letters, letters easier than complex shapes)
Neglect dyslexia: definition
failure to read words on left side of page
intentional neglect or limb akinesia: definition
reluctance to move limbs on L in absence to damage to corticospinal system
hemispatial akinesia: definition
pt fails to spontaneously use contralateral extremity, but may have good strength when focusing on that part
hypokinesia: definition
milder form of hemispatial akinesia, in which there is a delay in initiating movement
limbic-motivational neglect: definition
pts devalue the L side of space and act as if nothing important could happen on that side; there is no emotional salience for that side of space
Inattention: probes for milder versions
sensory extinction to double simultaneous stimulation: may still occur after hemi-attention improves, pt fails to report stimulation on contralateral side when both sides are stimulated simultaneously
Inattention: behaviors suggestive of
pts will recognize that the limbs are their own, but refer to them as though they were objects
Allesthesia: behaviors suggestive of
disturbance of body schema perception in tactile modailty, in which stimulation of one side of body is perceived as located on other side
4 types of motor neglect
akinesia, hypokinesia, motor extinction, motor impersistence
motor extinction: definition
pts who do not display akinesia when they are moving only one limb may do so when they must move both limbs simultaneously
motor impersistence: definition
inability to sustain a motor activity
spatial neglect
can occur in three dimensions of space: horizontal, vertical, and radial (near, far)
spatial neglect: behavioral manifestations and probes for
line bisection, cancelleation tasks, and drawing
spatial neglect: adaptive behavior manifestations
failure to groom or dress contralateral side
hemispatial neglect: frames of reference (2)
body-centered or environmental
Neglect classifications: sectors of space
personal neglect, peripersonal neglect (within reaching space), and far extrapersonal neglect (only when stimuli are out of reach)
anosagnosia: definition
unawareness or denial of deficits or of affected extremities
anosagnosia: behavioral manifestations
if pts are asked to complete a task wtih affected limb, will say they are left handed or claim to have done the task when they haven't
anosodiaphoria: definition
pt will admit to sensory or motor impairment, but be unconcerned about it, may follow a period of anosagnosia
Neglect: which hemisphere?
Much more frequent and severe after R hemi lesions because R hemi specializes in spatial distribution of attention.
Neglect: three cortical regions involved
Parietal (inferior), frontal, limbic
Neglect: subcortical regions involved
thalamus, striatum, superior collliculus
thalamic neglect: deficit attributed to
problem with engaging, not disengaging as seen in parietal lesions
Neglect: parietal component
inferior parietal lobe, key role is in spatial attention as integrating spatial map with motor output channels
small lesions here rarely lead to neglect, need subcortical damage and large parietal lesion
Neglect: frontal component
? plays critical role in attention network by converting plan and intentions into sequences of motor acts that shift focus of attention
lesions confined to frontal lobe can cause neglect
specific regions possibly frontal eye fields or inferior frontal gyrus
Neglect: limbic component
cingulate is least well understood, but may play role in identifying motivational relevance of events and sustaining effort
can have neglect with only cingulate gyrus lesion, rarely
Neglect: cingulate gyrus two proposed components
anterior- reflecting global attentional engagement
posterior- lateralized shifts of relevance and focal attention
Two hypotheses of mechanisms underlying neglect syndromes
reprsentational hypothesis (one proponent Bisiach)
attentional hypothesis (seems to be more accepted, proponents include Heilman, Posner, Mesulam)
Neglect: representational hypotheses defined
posterior parietal cortex is thought to contain an elaborate spatial representation of the external world, unilateral loss of this representation causes neglect
Representational hypotheses of neglect: classic experiment
Pts were asked to describe a cathedral in Milan; they failed to describe landmarks imagined on left side of scene
Which cathedral was it?
Piazza del Duomo in Milan
Piazza del Duomo experiment could be interpreted...
impaired representation (mental), impaired scanning of representation, inability to attend to contralesional hemispace
Cueing of Piazza del Duomo experiment patients
improved performance, suggesting attentional component, which isn't well explained by representational view
Unilateral Akinesia Hypothesis of Neglect
(an Attentional hypothesis proposed by Heilman)
defect in orienting to stimuli due to disruption in arousal system in affected hemisphere.
Unilateral Akinesia Hypothesis of Neglect
(an Attentional hypothesis proposed by Heilman): Problem
why don't most severe cases of neglect follow damage to RAS?
Covert Orienting Hypothesis of neglect (an attentional hypothesis proposed by Posner)
disengage, shift, engage model
neglect results from inability to shift away from intact hemispace
ATtentional network hypothesis of neglect (an attentional hypothesis proposed by Mesulam)
neglect is a network syndrome, represents damage to one or more components of a distributed network, represents a domain-specific impairment of spatial attention
Neglect: assessment issues, what to rule out
primary sensory deficits (by varying attentional cues),
motor deficits
unilateral hearing loss
does not occur after unilateral lesions, if pt has unilateral hearing loss, it is neglect
visual field cuts
are not affected by position of eyes in space, neglect is
sensory evoked potentials
are normal in neglect pts
assessment of neglect should include these modalities
auditory, visual, somesthetic
standardized testing for neglect
cancellation: look at omissions and search strategy
line bisection: deviations to ipsilateral side
drawing: copy or draw clock
reading and writing
Neglect: treatment by managing environment
arrange to reduce risk of injury, position important stimuli on R side, reduce competing/distracting stimuli, present some stimuli in neglected field for therapy
Neglect: training
operant techniques can improve exploration of contralesional space, but this might remain task specific and not generalize
Neglect: cueing
attentional cueing may help, bottom up cues include providing novel stimuli, top down cues include providing directions to attend
Neglect: behavioral goals
conscious knowledge of the importance of searching to left hemispace before engaging
kinesia paradoxica: definition
principally, an endo-evoked akinesia, with poor response to internal cues, but normal response to external cues (often seen in parkinson's disease)
endogenously evoked akinesia: definition
poor motor response to internal stimuli
exogenously evoked akinesia: definition
poor motor response to external stimuli
defective vigilance: definition
pt will be able to detect contralesional stimuli initially, but, with repeated stimulation, will eventually fail

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