Rehabilitation of Unilateral Spatial neglect


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This presentation is primarily based on an article Titled "Rehabilitation of Unilateral Spatial Neglect: New Insights from Magnetic Resonance Perfusion Imaging" by Argye E Hillis., Arch Phys Med Rehabil 2006;87(12 Suppl 2):S43-9.
Aim of this presenattaion was to give an insight to my students about Rehabilitation of Unilateral Spatial neglect

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Rehabilitation of Unilateral Spatial neglect

  1. 1. Rehabilitation of Unilateral Spatial Neglect Phinoj K Abraham, MOTh., Asst. Professor, SRM College of Occupational Therapy Presented on : 02-08-2012 1
  2. 2. 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
  3. 3. Overview • Introduction & Background • Heterogeneity(types) of Unilateral Neglect (USN) • Management of USN • Fluctuation in neglect severity after stroke 3
  4. 4. 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) & denile 3. Heterogeneity of the condition 4. Fluctuation in neglect severity after stroke 4
  5. 5. 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
  6. 6. 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 So I Thought to do little more together under a single label literature search • It appears that impairments of several different mechanisms converge to result in neglect 6
  7. 7. 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
  8. 8. A. Type Type Disorders of Input Inattention Disorders of Output Motor Neglect Pre motor Neglect 8
  9. 9. 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 9
  10. 10. 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 space 1. Neurobiology of Unilateral Neglect NEUROSCIENTIST 12(2):153–163, 2006. 10
  11. 11. B. Range • Range in terms of what the patient neglects Range Egocentric Allocentric 11
  12. 12. 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. 12
  13. 13. D. Orientation • “Left of what” • Person  Egocentric N • Stimuli  Allocentric N 13
  14. 14. Diverted…??! Let’s go back to the main article..!! 14
  15. 15. 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 together 15
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  17. 17. 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
  18. 18. Neuro-anatomic Evidence Contd… • Stimuli Centered neglect strongly associated with Hypoperfusion and/infarct of 1. Superior temporal gyrus 18 Hillis AE et,al., 2000
  19. 19. Neuro-anatomic Evidence Contd… • STUDY 2 - Ota et al., 2001 • Left viewer centered neglect was associated with hypoperfusion of Rt Viewer Centered USN angular gyrus • Stimulus centerd N – with Rt superior temporal gyrus 19 Stimulus Centered USN
  20. 20. 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 20
  21. 21. 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 hemisphere 21
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  23. 23. 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. 23
  24. 24. 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 24
  25. 25. 1. Prism Adaptation 25 Pisella et al. 2006
  26. 26. 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 26 Steven M. Miller et al 2000
  27. 27. 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 27
  28. 28. Theoretical frame of a possible pattern of left- and right-hemisphere contributions to the overall neural representation of egocentric space. 28 © Oxford University Press 1999 Oliveri M et al. Brain 1999;122:1731-1739
  29. 29. 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). 29
  30. 30. 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
  31. 31. 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 31
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  33. 33. 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 leftsided 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. 33
  34. 34. Effect of various Rehab strategies' in the Mx of USN • Prisam Adaptation • rTMS • Caloric stimulation Vibration   +  Several days Few Weeks 2 months – 1.5 years • Need more research to further comment on this point Argye E Hillis 2006 34
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  36. 36. Fluctuations in Neglect Severity after Stroke • Cause: • The main mechanisms underlying fluctuation in neglect is change in blood flow (hypoperfusion) 36
  37. 37. 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. 37
  38. 38. 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. 38
  39. 39. 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 visuospatial 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 on 03-08-12 • Caloric reflex test on 03-08-12 39
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