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

Background and Purpose-Two mechanisms for recovery from aphasia, repair of damaged language networks and activation of compensatory areas, have been p roposed. In this study, we investigated whether both mechanisms or one inst ead of the other take place in the brain of recovered aphasic patients Methods-Using blood oxygenation level-dependent functional MRI (fMRI), we s tudied cortical language networks during lexical-semantic processing tasks in 7 right-handed aphasic patients at least 5 months after the onset of lef t-hemisphere stroke and had regained substantial language functions since t hen. Results-We found that in the recovered aphasic patient group, functional la nguage activity significantly increased in the right hemisphere and nonsign ificantly decreased in the left hemisphere compared with that in the normal group. Bilateral language networks resulted from partial restitution of da maged functions in the left hemisphere and activation of compensated (or re cruited) areas in the right hemisphere. Failure to restore any language fun ction in the left hemisphere led to predominantly right hemispheric network s in some individuals. However, better language recovery, at least for lexi cal-semantic processing, was observed in individuals who had bilateral rath er than right hemisphere-predominant networks, Conclusions-The results indicate that the restoration of left-hemisphere la nguage networks is associated with better recovery and inversely related to activity in the compensated or recruited areas of the right hemisphere.