脑卒中后运动性失语发生机制的功能磁共振成像研究

Blood oxygen level and the pathogenic mechanism of expressive aphasia after stroke

目的利用血氧水平依赖性功能磁共振成像（BOLD—fMRI）技术研究脑卒中后运动性失语患者语言任务下脑区的激活特征，探讨运动性失语的发生机制。方法选择符合条件的运动性失语患者9例设为病例组，接受汉语标准失语症检查及图片命名任务状态下BOLD—fMRI检查。采用SPM8软件对fMRI数据进行图像预处理及统计分析，并与年龄相近的健康成人组作对比，分析两组间激活脑区的差异。结果健康成人组激活脑区一致性较好，均为视觉、语言、认知相关脑区，包括双侧额下回、颞上回、岛叶、基底核；左侧额上回、额中回、中央前回、丘脑、颞中回（P〈0．005）。脑卒中后运动性失语患者的激活脑区差异较大，可见如下特点：①所有患者左侧或／和右侧视觉处理有关皮质区（额中回、颞中回、舌回、梭状回等）均有激活；②左侧半球激活体积较对照组健康人明显较少（P〈0．01）；③左侧额下回（Broca’s区）、左侧额中回、右侧额下回（Broca镜像区）等与语言相关的脑区仅有部分激活，且激活较对照组健康人减弱；④右侧颞上回、双侧顶上小叶、左侧颞下回等脑区较对照组健康人激活增强（P〈0．05）。结论语言表达过程可能与多个相关脑区组成的网络有关，右侧半球参与了正常语占的产生过程。脑卒中后失语是由于病变通过直接破坏语言功能区或远隔效应所致，左侧半球多个脑区及右侧额下回（Broca镜像区）激活减弱，右侧半球部分脑区激活相对增强。右侧额下回在失语后不同的时期中所起的作用可能不同。

Objective To evaluate the activation patterns in the cortexcs 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 Rehabili- tation Research Center＇s aphasia examination （CRRCAE）. The control group received BOLD-fMRi only. SPM8 soft-ware 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 preccntral 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 aduhs. Regions related to language such as the left inferior frontal gyrus （Broea＇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. Conelusions 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.