Neural substrates of word generation during stroke recovery: the influence of cortical hypoperfusion.

Full Abstract

Several studies have demonstrated reorganization of cognitive and motor function caused by stroke. This study examined the influence of hypoperfused brain regions, in addition to the area of the infarct itself, on reorganization of the cognitive processes underlying word generation in stroke patients. In addition, we also sought to determine the influence of hypoperfusion on the blood oxygen level dependent/(BOLD) effect. Subjects with left and right subacute or chronic subcortical strokes, along with normal controls, were imaged while performing a verbal fluency task (word generation). The study population included six normal subject and six stroke patients with subcortical infarcts and cortical hypoperfusion in the middle cerebral artery territory who had recovered or improved markedly in word fluency. While normal subjects displayed a left-lateralized fronto-temporo-parietal and bilateral cingulo-striatal-thalamic-cerebellar network, the activation pattern of stroke patients was determined both by the hypoperfused regions and infarcted areas of the brain. Specifically, patients showed diminished BOLD effect in the cortical regions that were hypoperfused, even though their infarcts were subcortical, and showed increased BOLD effect in the homologous regions of the normal hemisphere. This finding raises the possibility that cortical hypoperfusion in the absence of infarct can cause shift of language functions to the opposite, intact hemisphere. However, reduced BOLD effect in the task relative to rest was found in hypoperfused regions in two patients, raising the possibility that regional function persisted, even though vascular reactivity was impaired. Results illustrate the complexities of functional imaging studies of recovery in patients with vascular lesions.

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Author information

Author/s: Prabhakaran, V (V); Raman, S P (SP); Grunwald, M R (MR); Mahadevia, A (A); Hussain, N (N); Lu, H (H); Van Zijl, P C M (PC); Hillis, A E (AE);

Affiliation: Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.

Grants: R01 DC05375 (Agency:NIDCD NIH HHS) ; R01 NS047691 (Agency:NINDS NIH HHS) ; R01 P41 RR1524 (Agency:NCRR NIH HHS)

Journal and publication information

Publication Type: Journal Article; Research Support, N.I.H., Extramural

Journal: Behavioural neurology (Behav Neurol), published in Netherlands. (Language: eng)

Reference: 2007-; vol 18 (issue 1) : pp 45-52

Dates: Created 2007/02/13; Completed 2007/03/29; Revised 2007/12/03;

PMID: 17297219, status: MEDLINE (last retrieval date: 12/26/2008)

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Adult
Brain Mapping
Case-Control Studies
Cerebral Cortex - blood supply; pathology
Cerebrovascular Circulation - physiology
Female
Functional Laterality - physiology
Humans

Infarction, Middle Cerebral Artery - pathology; physiopathology
Magnetic Resonance Imaging
Male
Middle Aged
Oxygen - blood; metabolism
Recovery of Function
Reference Values
Verbal Behavior - physiology

Associated Chemicals: Oxygen (7782-44-7)

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