visuospatial neglect Flashcards
(25 cards)
What is spatial neglect
An inability to report, respond or orient to stimuli presented on the side opposite a brain lesion not due to primary sensory or motor deficits (Heilman et al., 1985). It is a deficit of attention not vision. Targets on the nonimpaired side engage a participant more than targets on the impaired side.
What are Posner et al. (1984) 3 components of visual attention?
Engage attention on a target
Disengage attention from the target
Shift attention to new target
Which of Posner et al.,’s (1984) components are those with neglect suggested to struggle with?
Disengagement of attention from target
What behaviours do those with spatial neglect display
Difficulties navigating through space
Inability to perceive full table or objects around them.
Often actively stay away from stimulus that they can perceive meaning that more likely to bump into something on the left especially as space gets smaller as seen in doorway tasks.
Which brain areas are typically affected in neglect?
Often due to stroke in R parietal lobe. More severe and more long-lasting when associated with R hemisphere damage. Can be result of L sided injury however, less common. Mixed consensus on whether inferior parietal or temporal or even subcortical areas
Who supports neglect’s relation to the parietal area and who argues partietal / subcortical areas?
(MORT et al., 2003) support the involvement of the inferior parietal area whereas Karnath (Karnath, Ferber and Himmelback, 2001) AND (Karnath, Himmelbach and Rorden, 2002) argue the function of the temporal or subcortical areas.
What is the difference between visual field deficit and spatial attentional deficit
Visual field deficit can be adjusted for with mechanism such as turning head so full area could be viewed with movement. Visual field deficit means a narrower area of view. Spatial attentional deficit such as spatial neglect means that patient’s are unable to perceive certain areas due to attention being biased to a certain side. In neglect there is a gradient across space.
Which type of deficit is neglect related to?
Neglect is a deficit of spatial attention.
What is the effect of competition on spatial neglect?
Competition worsens neglect. For example, when there are stimuli on both sides, those with neglect will only report on the right side due to extinction.
What biases exist in visuospatial neglect?
Individuals with visuospatial neglect present with a lateralised bias to the ipsilateral side of the lesion. Likely in relation to imbalance post lesion leading to overactivity of the L hemisphere.
What methods are available methods for assessing spatial neglect? What are there limitations?
Star Cancellation task - quite a sensitive task
Copying task
Line bisection - not very objective, most people have a right sided bias
Computer tasks - e.g. feature / conjunction task - less risk learned effect
How often does spatial neglect occur in stroke occur?
80% of stroke patients affected in early stages of stroke
What is visuospatial neglect a predictor of?
Poor outcome as leads to:
- Higher disability level
- Longer length of stay in hospital
- Increased chance of requiring long-term care
what is the impact of neglect on peoples’ lives?
can mean unable to even use equipment that would help be independent such as powered wheel chairs, let alone be able to drive independently again. Can put them at increased danger to injury due to lack of awareness of obstacles around them.
What are challenges in rehabilitation of neglect?
Top down approach to treatment is not necessarily effective
What are possible approaches for rehabilitation in spatial neglect?
Top down treatments are “fundamentally atheoretical” Barret et al., 2006 suggesting that they are less valid. Much evidence suggesting that a bottom-up approach that is stimulus-driven that is insight-orientated self-modification
What is cueing and scanning?
Halligan, Donegan and Marshall found that with line bisection when cued to the Left were more likely to be closer to central, however, when cued to right hand side were even further from middle. It is a top down method however. It is an informal strategy and easy to use however clinical studies are inconclusive.
What is phasic alerting?
Again uses a top down strategy. Involves fixation, variable delay of cue, central sound cue although enabling patients to be aware of L side stimuli does not have long term effect.
Not mentioned in clinical revews.
Remains an informal strategy in rehab as difficult not to use.
What is limb activation?
Tested patients with neglect that tended to walk to R hand side of doorways. Found pateitns with movement in left hand, move with left hand out to side and this made them more central.
Exciting approach, however, why wasn’t left leg activation sufficient, what do if hemiparesis.
What is the theory behind limb activation?
That if movement and attention are so closely linked then eliciting movement on the contralesional side should improve neglect.
What is vestibular stimulation?
Can involve squirting cold water in someones ears can be used as a way of priming therapy. Example where patient that usually always turns to the right by stimulating through coldwater in L ear was able to turn to sit on bed to the left. Unsure of why works. Argument that by stimulating vestibular system stimulates R side of brain.
What is prism adaptation?
Put on prism goggles which causes shift, adjust to learn to get object despite shift, when taking glasses off end of shifting to left. Rossetti et al., 1998
What are the challenges moving from theory to practice in spatial neglect?
Often naturally complete ideas like cueing and phasic alerting.
Often have multiple people so have to be aware of those around and ensure that they don’t reverse cue back to the right.
Need more advanced engineered equipment to help patients.
what is spatial neglect in clinical terms?
Heterogeneous disorder
Affects sensory and motor systems
Affects different representations of space
Associated with anosognosia
A syndrome
