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

• Published in: Stroke (1970) Vol. 30; no. 11; pp. 2331 - 2340
• Main Authors: YUE CAO, VIKINGSTAD, E. M, GEORGE, K. P, JOHNSON, A. F, WELCH, K. M. A
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins 01-11-1999
• 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; Human; Nervous system diseases; Stroke; Cerebral cortex; Cardiovascular disease; Exploration; Functional analysis; Nuclear magnetic resonance imaging; Language disorder; Cerebral disorder; Vascular disease; Language; Central nervous system disease; Aphasia; Medical imagery; Neurological disorder; Cerebrovascular disease
• ISSN: 0039-2499; 1524-4628
• DOI: 10.1161/01.STR.30.11.2331

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.