Rehabilitation of Unilateral Spatial

Neglect

Phinoj K Abraham, MOTh.,Asst. Professor,

SRM College of Occupational TherapyPresented on : 02-08-2012

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Key Article

“Rehabilitation of Unilateral Spatial

Neglect: New Insights from

Magnetic Resonance Perfusion

Imaging”

Argye E Hillis., Arch Phys Med Rehabil 2006;87(12 Suppl 2):S43-9.2

Overview

• Introduction & Background

• Heterogeneity(types) of Unilateral Neglect (USN)

• Management of USN

• Fluctuation in neglect severity after stroke

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Introduction

• USN- often a tremendous challenge to rehabilitation professionals

• Contributors of this challenges

1. Anosognosia (failure to recognize deficits)2. Anosodiaphoria (Lack of concern regarding

defecits) & denile3. Heterogeneity of the condition4. Fluctuation in neglect severity after stroke

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Heterogeneity of USN

• Authors vary considerably in dividing this syndrome• Near Vs. Far neglect• Intentional Vs. Attentional neglect• Visual Vs. Motor / Tactile Neglect• Personal Vs. Peripersonal Neglect• Viewer centered (Egocentric) Vs. Stimuli Centered

(Allocentric) neglect• Motor Vs. Premotor Neglect

• So Much….??!! 5

From this we can understand that…

• Unilateral neglect is a heterogeneous syndrome with several subtypes.

• It’s possible that many distinct disorders have been inaccurately lumped together under a single label

• It appears that impairments of several different mechanisms converge to result in neglect

So I Thought to do little more

literature search

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Classification

• Despite the previously mentioned limitations, we

may loosely describe unilateral neglect with four

overlapping variables: • Type• Range• axis and • orientation.

Ref: Wikipedia

But No Cross Ref..!!7

A. Type

Type

Disorders of Input

Inattention

Disorders of Output

Motor Neglect

Pre motor Neglect

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Type Contd…

• The neglect of input, • “Attentional” or “visual-perceptual”neglect 1

• Ignoring contralesional sights, sounds, smells, or

tactile stimuli.

• Patients may have “representational neglect,”2

patients may ignore the left side of memories,

dreams, and hallucinations.1. Neurobiology of Unilateral Neglect NEUROSCIENTIST 12(2):153–163, 2006.

2. Ste´phanie Ortigue, MS et al 2001 Ann Neurol 2001;50:401–404

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Type Contd…

• Output Neglect

• Motor Neglect1

• Patient does not use a contralesional limb despite the

neuromuscular ability to do so.

• Premotor /Intentional Neglect or directional hypokinesia1

• Patient can move unaffected limbs ably in ipsilateral

space, but has difficulty directing them into

contralesional space1. Neurobiology of Unilateral Neglect NEUROSCIENTIST 12(2):153–163, 2006.

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B. Range

• Range in terms of what the patient neglects

Range

Egocentric Allocentric

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C. Axis

• Most tests for neglect look for rightward or leftward

errors.

• But patients may also neglect stimuli on one side of

a horizontal or radial axis.

• For example, when asked to circle all the stars on a

printed page, they may locate targets on both the

left and right sides of the page while ignoring those

across the top or bottom.

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D. Orientation

• “Left of what”

• Person Egocentric N

• Stimuli Allocentric N

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Diverted…??!

Let’s go back to the main article..!!14

Egocentric Vs. Allocentric Neglect

• Based on the ‘distinction between reference frame of

USN’• Egocentric also called as viewer centered N.

• “neglect of the contraleisional side of the view of the patient”

• Allocentric also called as Stimulus Centered N.

• “Neglect of contralesional side of each stimulus in the

view”

• Some patient can have both type of neglect together15

Neuro-Anatomic

Evidence

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Neuro-anatomic Evidence

• STUDY 1 - Hillis AE et, al., 2000

• Authors Concluded that

• Viewer Centered neglect

strongly associated with

Hypoperfusion and/infarct of

1. Right angular gyrus

2. Right supra marginal gyrus &

3. Right visual association cortex 17

Neuro-anatomic Evidence Contd…

• Stimuli Centered neglect

strongly associated with

Hypoperfusion

and/infarct of

1. Superior temporal

gyrus

Hillis AE et,al., 200018

Neuro-anatomic Evidence Contd…

• STUDY 2 - Ota et al., 2001

• Left viewer centered

neglect was associated

with hypoperfusion of Rt

angular gyrus

• Stimulus centerd N –

with Rt superior

temporal gyrus

Viewer Centered USN

Stimulus Centered USN

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Neuro-anatomic Evidence Contd…

• STUDY 3 Corbetta & Shulman proposed that,

• spatial neglect requires damage or dysfunction of 2

separate attentional mechanisms with different

localizations:

1. a top-down, spatially specific attentional

mechanism in left or right intraparietal sulcus

(dorsal parietal), biased toward attending to space

in the opposite visual field or space defined by the

midline of the trunk and

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Neuro-anatomic Evidence Contd…

2) a bottom-up attentional mechanism devoted to

reshifting of attention toward a stimulus on either side

of space, located in right ventral parietal (angular gyrus

- temporoparietal junction).

• On this hypothesis, USN is more common after right

hemisphere stroke than left-hemisphere stroke,

because a single lesion can affect both mechanisms

only in the right hemisphere21

Treatment of

Egocentric USN

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Principles of Rx

• Rehabilitation for viewer-centered USN should focus on both 1. shifting attention further to the left of the viewer

and 2. increasing the sustained attention and the size of the

viewer centered attentional window or work space.

• Rehabilitation of stimulus-centered USN should focus on shifting attention further to the left of stimuli or increasing the size of the stimulus centered attentional window.

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Treatment of Egocentric USN

A. Rx methods to shift attention further to the left

of the viewer

1. Prism Adaptation

2. Caloric Stimulation

3. Trans cranial magnetic stimulation

4. Vibrationa Stimulation on the posterior neck

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1. Prism Adaptation

Pisella et al. 2006

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2. Caloric Stimulation

• The caloric stimulation

procedure involved irrigating

the external ear canal with iced

water until subjects reported

vertigo and examiners observed

nystagmus.

• It can also induce a temporary

remission ofhemispatial neglect

Steven M. Miller et al 2000

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3. Transcranial magnetic stimulation (rTMS)

• By Kinsburne 1970

• Posited that, each hemisphere spatial attention mechanism in

each dorsal parietal cortex inhibited by the other hemisphere

• In normal brain tendency to rightward orienting supported by

the left hemisphere.

• Right hemisphere lesions determine left neglect by exaggerating

this physiologic rightward bias.

• Left hemisphere lesions would only rarely provoke right neglect

because they release a right hemisphere attentional vector,

which is less powerful than the left one Paolo Bartolomeo, MD 1999

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Theoretical frame of a possible pattern of left- and right-hemisphere

contributions to the overall neural representation of egocentric space.

Oliveri M et al. Brain 1999;122:1731-1739© Oxford University Press 1999

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3. TMS Contd…

• Researches showed that,

• In right brain-damaged patients, left frontal

TMS (trans cranial magnetic stimulation) would

interfere with a hypothetical left frontal–right

parietal inhibition vector, with the net effect of

a right parietal disinhibition and consequent

partial restoration of left extinctions (black

arrow in the previous picture).

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4. Vibration

• Vibratory stimulation of the posterior neck

muscles has also been shown to improve USN.

(Brighina F et al 2003)

• This intervention would ameliorate

egocentric,rather than allocentric, neglect

(Bottini G et al 2001) 30

B. Rx methods to improve sustained attention • Pharmacological Intervention

• Noradrenergic pathway stimulating drugs like ‘guanficine’

• Need Further research in this area Argye E Hillis 2006

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Treatment of

Allocentric USN

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Treatment of Allocentric USN• By increasing the size of “Attentional window”

• In their single case study Hillis AE et al found out that• the size of the “attentional window” for stimulus

recognition was increased by presenting large circles in the same block of trials with small circles with left-sided or right-sided targets (gaps).

• Improved detection of left-sided targets in the small circles (butnot in the large circles) was achieved when large circles were presented in the same block of trials.

• It was hypothesized that this improvement was due to increasing the size of the attentional window with the larger circles.

Cortex. 1999 Jun;35(3):433-42.

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Effect of various Rehab strategies' in the Mx of USN

• Prisam Adaptation Several days• rTMS Few Weeks• Caloric stimulation + Vibration 2 months – 1.5 years

• Need more research to further comment on this point Argye E Hillis 2006

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Fluctuations in Neglect

Severity after Stroke

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Fluctuations in Neglect Severity after Stroke

• Cause:

• The main mechanisms underlying fluctuation

in neglect is change in blood flow

(hypoperfusion)

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Management - Summery

• In Acute Stage

• Earlier (in acute stage) medical management for

increasing blood circulation is has a great

effectiveness.

• In Chronic Stage

• Prism adaptation, rTMS, caloric stimulation, and

vibrotactile stimulation may be effective in more sub

acute or chronic stages of stroke.

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Conclusion• Damage or dysfunction of right angular gyrus and intraparietal

sulcus respectively lead to an abnormal shift of attention to the right of the viewer and reduced vigilance or attentional window. Together, these deficits cause left viewer-centered neglect.

• In contrast, damage or dysfunction of right superiortemporal cortex seems to cause left stimulus-centered neglect.

• reperfusion therapy to improve blood perfusion to brain is likely to have an effect only in the acute stage of stroke.

• prism adaptation, rTMS, caloric stimulation, and vibrotactile stimulation may be effective in more subacute or chronic stages of stroke.

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References• Scientific Articles

• ARGYE E. HILLIS Rehabilitation of Unilateral Spatial Neglect: New insights from magnetic resonance perfusion imaging Arch Phys Med Rehabil 2006;87(12 Suppl 2):S43-9

• Pisella et al., 2006 Prism adaptation in the rehabilitation of patients with visuo-spatial cognitive disorders Laure Curr Opin Neurol 19:000–000. 2006 Lippincott Williams & Wilkins.

• Steven M. Miller Trung T. Ngo., Studies of caloric vestibular stimulation: implications for the cognitive neurosciences, the clinical neurosciences and Neurophilosophy Acta Neuropsychiatrica 2007: 19: 183–203

• ARGYE E. HILLIS Neurobiology of Unilateral Spatial Neglect NEUROSCIENTIST 12(2):153–163, 2006

• Paolo Bartolomeo, et al., ; Left unilateral neglect or Right hyperattention? NEUROLOGY 1999;53:2023–2027

• Oliveri M et al. Theoretical frame of a possible pattern of left- and right-hemisphere contributions to the overall neural representation of egocentric space. Brain 1999;122:1731-1739

• Hillis AE, Mordkoff JT, Caramazza A. Mechanisms of spatial attention revealed by hemispatial neglect. Cortex. 1999 Jun;35(3):433-42.

• Web Resources• Hemi lateral Neglect http://en.wikipedia.org/wiki/Hemispatial_neglect on 03-08-12• Caloric reflex test http://en.wikipedia.org/wiki/Caloric_reflex_test on 03-08-12

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