缺血性脑卒中认知功能障碍患者静息态下海马功能连接的功能性磁共振成像研究

Resting state functional magnetic resonance imaging of the hippocampus after ischemic stroke

目的 采用静息态功能性磁共振成像（fMRI）观察缺血性脑卒中认知功能障碍患者海马,尤其是与默认网络系统的功能连接模式的异常情况及其可能的机制.方法 选取缺血性脑卒中后认知功能障碍患者15例为病例组,健康老年人10例为健康对照组.采用静息态fMRI,选择左、右两侧海马作为感兴趣区,分别与全脑做相关分析,获得健康对照组和病例组的脑功能连接激活图,观察其左右海马与全脑的功能连接模式.结果 与健康对照组比较,病例组与海马功能连接减弱脑区主要包括扣带回、额叶（上、中、下回）、顶下小叶、颞上回等,组间差异有统计学意义（P＜0.05）;而功能连接增强的脑区主要包括小脑后叶、枕叶、颞叶内侧、楔前叶、距状沟等,组间差异有统计学意（P＜0.05）.结论 脑卒中后认知功能障碍患者海马功能连接模式存在异常,相关脑区之间的功能连接减弱可能是引起脑卒中后认知功能减弱的原因之一,而功能连接增强提示脑卒中认知功能障碍患者可能同时存在相应的代偿机制.

Objective To observe the functional connectivity （FC） pattern linking the hippocampus with the rest of the brain in ischemic stroke patients with cognitive dysfunction,especially the default mode network （DMN）.Methods Resting-state functional connectivity magnetic resonance imaging （fMRI） was performed on 15 ischemic stroke patients with cognitive dysfunction （the patient group） and 10 normal elderly controls.The bilateral hippocampus was the region of interest.Correlation analyses yielded a mapping of cerebral functional connectivity activation for both groups.Results Compared with the healthy controls,the patient group showed weakened functional connectivity between the hippocampus and other regions including the cingulate gyrus,the superior,middle and inferior frontal lobes,the inferior parietal lobule and the superior temporal gyrus.But there was enhanced functional connectivity with the cerebellar posterior lobe,the occipital lobe,the medial temporal lobe,the precuneus and the calcarine.The results were significantly different between the two groups.Conclusion The functional connectivity pattern of the hippocampus is impaired in stroke patients with cognitive dysfunction.Reduced functional connectivity between brain regions may be one cause of cognitive dysfunction after stroke,and enhanced functional connectivity may be an appropriate compensatory mechanism.