Cortical language activation in stroke patients recovering from aphasia with functional MRI

Two mechanisms for recovery from aphasia, repair of damaged language networks and activation of compensatory areas, have been proposed. In this study, we investigated whether both mechanisms or one instead of the other take place in the brain of recovered aphasic patients. Using blood oxygenation le...

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Bibliographic Details
Published in:Stroke (1970) 1999-11, Vol.30 (11), p.2331-2340
Main Authors: YUE CAO, VIKINGSTAD, E. M, GEORGE, K. P, JOHNSON, A. F, WELCH, K. M. A
Format: Article
Language:English
Subjects:
Adult
Aphasia - classification
Aphasia - metabolism
Aphasia - physiopathology
Biological and medical sciences
Cerebral Cortex - metabolism
Cerebral Cortex - physiopathology
Female
Follow-Up Studies
Frontal Lobe - physiopathology
Functional Laterality - physiology
Humans
Image Processing, Computer-Assisted - methods
Language
Language Tests
Magnetic Resonance Imaging - methods
Male
Medical sciences
Middle Aged
Neural Pathways - metabolism
Neural Pathways - physiopathology
Neurology
Oxygen - blood
Oxygen Consumption - physiology
Parietal Lobe - physiopathology
Recovery of Function
Recruitment, Neurophysiological - physiology
Stroke - metabolism
Stroke - physiopathology
Temporal Lobe - physiopathology
Vascular diseases and vascular malformations of the nervous system
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Summary:Two mechanisms for recovery from aphasia, repair of damaged language networks and activation of compensatory areas, have been proposed. In this study, we investigated whether both mechanisms or one instead of the other take place in the brain of recovered aphasic patients. Using blood oxygenation level-dependent functional MRI (fMRI), we studied cortical language networks during lexical-semantic processing tasks in 7 right-handed aphasic patients at least 5 months after the onset of left-hemisphere stroke and had regained substantial language functions since then. We found that in the recovered aphasic patient group, functional language activity significantly increased in the right hemisphere and nonsignificantly decreased in the left hemisphere compared with that in the normal group. Bilateral language networks resulted from partial restitution of damaged functions in the left hemisphere and activation of compensated (or recruited) areas in the right hemisphere. Failure to restore any language function in the left hemisphere led to predominantly right hemispheric networks in some individuals. However, better language recovery, at least for lexical-semantic processing, was observed in individuals who had bilateral rather than right hemisphere-predominant networks. The results indicate that the restoration of left-hemisphere language networks is associated with better recovery and inversely related to activity in the compensated or recruited areas of the right hemisphere.
ISSN:0039-2499
1524-4628
DOI:10.1161/01.STR.30.11.2331