Hypoperfusion of Wernicke's area predicts severity of semantic deficit in acute stroke

Hillis, Argye E.; Wityk, Robert J.; Tuffiash, Elizabeth; Beauchamp, Norman J.; Jacobs, Michael A.; Barker, Peter B.; Selnes, Ola A.

doi:10.1002/ana.1265

Cited by 191 publications

(137 citation statements)

References 45 publications

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“…Hypoperfusion was defined as Ͼ2.5 s mean delay in time-to-peak arrival of contrast across voxels in the ROI relative to the homologous region in the left hemisphere. This threshold was based on evidence that tissue with this degree of hypoperfusion is dysfunctional, although it may not be at risk for progressing to infarction, whereas a delay of Ͻ2.5 s is not associated with dysfunction (Hillis et al, 2000(Hillis et al, , 2001. ROIs were defined manually using the Damasio and Damasio (1989) templates.…”

Section: Methodsmentioning

confidence: 99%

Anatomy of Spatial Attention: Insights from Perfusion Imaging and Hemispatial Neglect in Acute Stroke

Hillis¹,

Newhart²,

Heidler³

et al. 2005

J. Neurosci.

292

223

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The site of lesion responsible for left hemispatial neglect after stroke has been intensely debated recently. Some studies provide evidence that right angular lesions are most likely to cause left neglect, whereas others indicate that right superior temporal lesions are most likely to cause neglect. We examine two potential accounts of the conflicting results: (1) neglect could result from cortical dysfunction beyond the structural lesion in some studies; and (2) different forms of neglect with separate neural correlates have been included in different proportions in separate studies. To evaluate these proposals, we studied 50 patients with acute right subcortical infarcts using tests of hemispatial neglect and magnetic resonance diffusion-weighted and perfusion-weighted imaging performed within 48 h of onset of symptoms. Left "allocentric" neglect (errors on the left sides of individual stimuli, regardless of location with respect to the viewer) was most strongly associated with hypoperfusion of right superior temporal gyrus (Fisher's exact test; p Ͻ 0.0001), whereas left "egocentric" neglect (errors on the left of the viewer) was most strongly associated with hypoperfusion of the right angular gyrus ( p Ͻ 0.0001). Patients without cortical hypoperfusion showed no hemispatial neglect. Because the patients did not have cortical infarcts, our data show that neglect can be caused by hypoperfused dysfunctional tissue not detectable by structural magnetic resonance imaging. Moreover, different forms of neglect were associated with different sites of cortical hypoperfusion. Results help explain conflicting results in the literature and contribute to the understanding of spatial attention and representation in the human brain.

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Section: Methodsmentioning

confidence: 99%

Anatomy of Spatial Attention: Insights from Perfusion Imaging and Hemispatial Neglect in Acute Stroke

Hillis¹,

Newhart²,

Heidler³

et al. 2005

J. Neurosci.

292

223

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“…For instance, imaging diffusion and perfusion a few hours after ischemic stroke can reveal functionally impaired regions that are not at the core of the lesion. This advance will lead to a better understanding of the brain-symptom relationships in the acute phase of aphasia (160). Very brief and localized magnetic pulses produced by transcranial magnetic stimulation (TMS) can be used to transiently stimulate neural populations and induce either facilitation or inhibition of cognitive operations (277).…”

Section: New Imaging Techniquesmentioning

confidence: 99%

Renewal of the Neurophysiology of Language: Functional Neuroimaging

Démonet¹,

Thierry²,

Cardebat³

2005

Physiological Reviews

369

207

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Functional neuroimaging methods have reached maturity. It is now possible to start to build the foundations of a physiology of language. The remarkable number of neuroimaging studies performed so far illustrates the potential of this approach, which complements the classical knowledge accumulated on aphasia. Here we attempt to characterize the impact of the functional neuroimaging revolution on our understanding of language. Although today considered as neuroimaging techniques, we refer less to electroencephalography and magnetoencephalography studies than to positron emission tomography and functional magnetic resonance imaging studies, which deal more directly with the question of localization and functional neuroanatomy. This review is structured in three parts. 1) Because of their rapid evolution, we address technical and methodological issues to provide an overview of current procedures and sketch out future perspectives. 2) We review a set of significant results acquired in normal adults (the core of functional imaging studies) to provide an overview of language mechanisms in the “standard” brain. Single-word processing is considered in relation to input modalities (visual and auditory input), output modalities (speech and written output), and the involvement of “central” semantic processes before sentence processing and nonstandard language (illiteracy, multilingualism, and sensory deficits) are addressed. 3) We address the influence of plasticity on physiological functions in relation to its main contexts of appearance, i.e., development and brain lesions, to show how functional imaging can allow fine-grained approaches to adaptation, the fundamental property of the brain. In closing, we consider future developments for language research using functional imaging.

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“…3,8,[11][12][13]16,18,21,22,24,25,28 Such studies describe the size of perfusion imaging deficit, perfusion-diffusion mismatch, and size of DWI deficit. In some cases, studies compared the predictive ability of different parameters in an attempt to identify the strongest predictors of later clinical outcome.…”

Section: Representative Articles From Acute Cerebral Ischemia Perfusimentioning

confidence: 99%

Systematic Review of CT and MR Perfusion Imaging for Assessment of Acute Cerebrovascular Disease

Provenzale¹,

Shah²,

Patel³

et al. 2008

AJNR Am J Neuroradiol

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Hypoperfusion of Wernicke's area predicts severity of semantic deficit in acute stroke

Cited by 191 publications

References 45 publications

Anatomy of Spatial Attention: Insights from Perfusion Imaging and Hemispatial Neglect in Acute Stroke

Anatomy of Spatial Attention: Insights from Perfusion Imaging and Hemispatial Neglect in Acute Stroke

Renewal of the Neurophysiology of Language: Functional Neuroimaging

Systematic Review of CT and MR Perfusion Imaging for Assessment of Acute Cerebrovascular Disease

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