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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Cao
Y
Y
NMR Research Center, Department of Neurology, Henry Ford Health Sciences Center, Case Western Reserve University, Detroit, MI, USA. yue@radiology.msu.edu
Vikingstad
E M
EM
George
K P
KP
Johnson
A F
AF
Welch
K M
KM
D000328:Adult; D001037:Aphasia / Q000145:classification / Q000378:metabolism / Q000503:physiopathology*; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology*; D005260:Female; D005500:Follow-Up Studies; D005625:Frontal Lobe / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007802:Language; D007807:Language Tests; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009434:Neural Pathways / Q000378:metabolism / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010296:Parietal Lobe / Q000503:physiopathology; D020127:Recovery of Function; D011999:Recruitment, Neurophysiological / Q000502:physiology; D020521:Stroke / Q000378:metabolism / Q000503:physiopathology; D013702:Temporal Lobe / Q000503:physiopathology
D010100:Oxygen