Neglect and Rehabilitation Flashcards
Left-sided hemianopia
Left homonymous hemianopia is a visual condition that causes a loss of vision in the left half of the visual field in the left eye and the right half of the visual field in the right eye
left sided hemianopia causes
Neglect typically involves damage to
parietal, not occipital, lobe but may
include optic radiations
unilateral neglect
a neurological condition where individuals fail to attend to or recognize one side of their visual field or environment, typically the side opposite to a brain injury, most commonly after damage to the right hemisphere, causing neglect of the left side.
Anosognosia
– unawareness, or denial of illness or
deficit (e.g. hemiplegia, hemianopia)
Anosodiaphoria
indifference to illness or disability
effects of anosognosia and anosodiaphoria
Both associated with damage to right frontal lobe.
– Both contribute to problems for rehabilitation
Definition of neglect
“Following right hemisphere brain damage a patient without impairment of intellectual functioning appears to ignore, forget or turn away from the left side of space- as if that half of the world has ceased to exist…” Mesulam, (1985)
Central anchor
spatial coordinates can vary with size, content of stimulus array and the behavioural response required
left vs right hemipshere neglect
Chronic neglect associated with Right hemisphere damage
Left hemisphere damage can produce right neglect but this is usually less severe and resolves quickly
Nature of brain damage (1)
Cerebrovascular ischemia (restriction) or haemorrhage (bleeding) produces tissue damage
Nature of brain damage (2)
– Right middle cerebral artery (MCA) damage usually
involving right inferior parietal lobe (IPL)
Husain & Nachev, (2006)
Nature of brain damage (3)
Frontal neglect (Husain and Kennard, 1996)
Right hemisphere Brodmann’s Area 44 premotor cortex (equivalent of Broca’s area in L.H.)
nature of brain damage (4) MCA
Middle Cerebral Artery (MCA)
Contour map of lesion location (CT) of 8 neglect patients - right hemisphere
Overlap - Inferior parietal lobe (IPL) – associated with sever neglect
(Superior parietal lobe – may cause extinction and mis-reaching)
Vallar & Perani, 1986
early cases (1)
Brain (1941)
Three patients with parieto-occipital damage “When asked to describe the route from the tube station to her flat she described this in detail correctly and apparently visualising landmarks, but she
consistently said right instead of left for the turnings…”
early cases (2)
Paterson and Zangwill’s (1944) classic
case
39 year old male, penetrating wound right
parieto-occiptal region (explosion)
X-ray possible (unlike earlier cases) confirmed involvement of right inferior parietal lobe (supramarginal gyrus/angular gyrus)
early case (2,2)
Unimpaired: Speech and language, reading words, writing and
calculation, object recognition, depth perception
Deficits
- Left hemianopia (upper quadrant improved), neglect,
extinction, visual-construction, agnosia for left side of space
(collided with objects)
- Left eye movements – problem reading text
Allochiria - objects transposed from left to right side
-Setting time on a clock e.g. twenty to two, set as twenty past two
-Pointing (eyes closed) to objects on left – pointed towards right showing an ipsilesional spatial bias
Clinical tests of neglect (1)
Confrontational testing for visual fields and extinction
fingers at opposing sides of peripheral and see if they recognise finger before it gets to middle
Clinical tests of neglect (3)
Touch – hemianaesthesia loss of
touch
Visual and tactile extinction
Clinical tests of neglect (2)
Anosognosia
e.g. Bisiach’s 4-point scale of awareness:
- 0 = disorder spontaneously acknowledged
- 1 = reported only following specific questioning
- 2 = acknowledged only after its demonstration
- 3 = no acknowledgement of the disorder
drawing test of neglect
right side will be far more detailed than left in those with left sided hemianopia
behavioural innatention tests
…
nelgect dyslexia
ommissions and substitutes where they give a similar response but not accurate
Fred “Red.”
Object-based neglect
…
Chimaeric faces and objects
…
Heterogeneous
- Not a unitary disorder
– Representations of space not unitary
– Personal space, peripersonal (reaching) and extrapersonal space
Representations of space
Retinotopic
spatial layout on retina
Representations of space
egocentric
– location in relation to own body (to my left) IPL
Representations of space
allocentric
independent of own position (episodic memory e.g. north of here, road map)
hippocampus
quote about rehabilitation
“Rehabilitation should have a central place in both theoretical and clinical thinking..’”
(Robertson et al. 1993)
real world findings
Neglect is a predictor of poor Activities Daily
Living (ADL) functioning Even after florid symptoms have resolved
Rehabilitation strategies should be tied to
theoretical models and inform these models insights into mechanisms involved in neglect.
Heilman’s Attentional-intentional model
Neglect reflects a failure to attend (detect) and intent (to make action)
Representation of left and right space mapped across both hemispheres
*Right-hemisphere dominant role (both directions), left-hemisphere attends to right only
* Failure to attend and intend linked to hypoarousal (decrease) following right-hemisphere damage
Kinsbourne’s vectorial model
- Each hemisphere involved in directing contraversive attention (e.g. L.H. – rightward)
- L.H. stronger orienting tendency (even in non brain damage) but natural inhibition
- Damage to RH – leaves LH overactive with rightward bias of attention
- Activation of hemisphere (e.g. LH by language) induces shift attention
Rizzolatti’s pre-motor model
Spatial attention mediated by neural circuits
each involved in different region of space
* Personal – own body
* peripersonal – around body
* extrapersonal – beyond reach
* Combined activity of neurons in this circuit
form representation used to control goaldirected responses
* Neglect is a deficit of spatial awareness
resulting from damage to the underlying
neural representation of space
Behavioural interventions
Based on the use of strategies to
help patient orient to neglected
side of space
E.G. Visual scanning training
Involves instructions and cueing to
get patient to make leftward eye
and head movements ‘Scanning machine’
more on scanning training
