Blood oxygen level and the pathogenic mechanism of expressive aphasia after stroke / 中华物理医学与康复杂志

ABSTRACT

Objective To evaluate the activation patterns in the cortexes of expressive aphasics after stroke so as to explore the pathogenic mechanism of expressive aphasia.Methods Blood oxygen level dependent functional magnetic resonance imaging (BOLD-fMRI) was the method of choice.It was administered to 9 subjects with expressive aphasia at 1 to 3 months post-stroke onset and to 10 healthy controls.Active areas in the patients' brains were observed using a block-designed picture-naming task,and language function was tested with the China Rehabilitation Research Center's aphasia examination (CRRCAE).The control group received BOLD-fMRI only.SPM8 software was used to process the fMRI data.Results Differences were observed in the mapping of activated areas between the two groups,but many activated areas showed no difference.Significant differences in activation were observed in areas associated with vision,language and cognition,including the bilateral inferior frontal gyrus,the bilateral superior temporal gyrus,the bilateral insula,the bilateral basal ganglia,the left superior frontal gyrus,the left middle frontal gyrus,the left precentral gyrus,the left thalamus,and the left middle temporal gyrus.All the patients had activated cortex regions associated with visual processing in the left and/or right hemisphere,such as the middle frontal gyrus,the middle temporal gyrus,the lingual gyrus and the fusiform gyrus.The activation volumes in the left hemisphere were significantly smaller than those in normal adults.Regions related to language such as the left inferior frontal gyrus (Broca's area),the left middle frontal gyrus,and the right inferior frontal gyrus (the mirror region of Broca's area) were activated in some of them.While the activation frequency,activated volume and activation intensity generally were all less in the patients than in the controls,the activation intensity in the right superior temporal gyrus,the bilateral superior parietal lobule and the left inferior temporal gyrus were stronger.Conclusions Language production may be associated with multiple,interconnected regions.The right hemisphere participates in natural language processing.Aphasia damages both linguistic and cognitive areas,reducing activation in Broca's aphasia.Activation areas in the left hemisphere and the right inferior frontal gyrus decrease significantly,while some regions in the right hemisphere are relatively more activated.The right inferior frontal gyrus may play a different role in language recovery at different periods of aphasia after stroke.