The Relation Of The Dynamic Changes In Distant Parts And Cognitive Function After Local Subcortical Infarction

Stroke had the characteristics of the high incidence, high morbidity, high mortality and high recurrence rate.75% of the survivors had different degree of disability, and 90% had cognitive impairment. Currently, commonly used in clinical neuropsychological such as MMSE, MoCA, etc. detect early cognitive dysfunction. But it is easy to be affected by the subjectivity of inspectors, so did the region, race, culture, education and the other differences. Still need other objective clinical approach to diagnosis.Objective To assess the microstructual damage of whole brain and it’s relationship with the cognitive function score in patients with subcortical infarction through voxel-based analysis of diffusion tensor imaging (DTI).Method Twelve consecutive acute patients were recruited within forty-eight hours following the onset of stroke who were admitted into Subei Hospital department of Neurology from June 2014 to December 2014. Patients had the unilateral subcortical infarction by brain MRI scan confirmed. All the patients got cognitive function score before undergoing diffusion tensor imaging with a American GE 3.0T MR imager in the first, the forth and the twelfth week respectively following a predefined protocol. Ten healthy volunteers were examined once using the same MRI and DTI protocol during the study period with sex, age, culture level matched. We calculated fractional anisotropy (FA) with PANDA software(a pipeline toolbox for analyzing brain diffusion images). The statistical MRI analyses were carried using REST software(A Toolkit for Resting-State Functional Magnetic Resonance Imaging Data Processing). We preformed voxel-based analysis of variance with REST to detect brain areas differences among 2 groups using FA values as the dependent variables at different time points. A correlation analysis was also performed between the FA values and the score of MMSE and MoCA, two test of global cognitive function.Result ① Voxel-based analysis:In the time-points of 1 week, FA values were lower in the patients than in the healthy controls in the Frontal lobe, parietal lobe, insula, temporal lobe, thalamus, midbrain, medial frontal gyrus, inferior parietal lobul, putamen and claustrum, left and right sides are basically the same. In the time-points of 4 weeks, FA values were lower in the patients than in the healthy controls in the Frontal lobe, parietal lobe, insula, limbic, midbrain, medial frontal gyrus, middle frontal gyrus, postcentral gyrus, cingulate gyrus, thalamus, putamen and claustrum. In the time-points of 12 weeks, FA values were lower in the patients than in the healthy controls in the frontal lobe, insula, parietal, medial frontal gyrus, middle frontal gyrus, thalamus, putamen and claustrum. They are mainly associated with white matter fiber.② Compared with the healthy controls, FA values of the patients with only right lesion showed little difference in the ipsilateral brain, neither did the left. And no statistical difference was noticed in FA values between the three groups of patients.③ WM atlases-based analysis:In the comparison between the three groups of patients and the controls, FA values showed the statistical difference in the bilateral posterior limb of the internal capsule genu, bilateral posterior, corona radiate and external capsule in the other time points (P<0.05), but showed no statistical difference in the left posterior limb of the internal capsule genu and bilateral posterior in the time-points of 12 weeks (P>0.05).④ In the three time-points, the scores of MMSE and MoCA in the patients were statistically different from the controls(P<0.05), but the scores of MMSE not in the time-points of 4weeks (P>0.05). And no statistical difference was noticed between the scores of MMSE or MoCA in the three time-points.⑤ There was a positive correlation between FA values and the performance of MMSE and MoCA in the patients. In the time-points of 1 week, FA values in the occipital lobe, lingual gyrus, limbic lobe, posterior cingulate, calcarine_L, cerebellum anterior Lobe, cerebellum posterior lobe, precuneus and cuneus showed significant correlations with the scores of MMSE, the correlation coefficient was 0.925. But it showed no correlation between FA values and the performance of MMSE in the time-points of 4 weeks and 12 weeks. Regions related to MoCA scores in the time-points of 1 week were the occipital lobe, lingual gyrus, limbic lobe, posterior cingulate, calcarine_L, cerebellum anterior Lobe, cerebellum posterior lobe, precuneus and cuneus, the correlation coefficient was 0.877. Regions related to MoCA scores in the time-points of 4 weeks were the cerebellum posterior lobe, inferior semi-lunar lobule, cerebellar tonsil, precentral gyrus, brainstem and putamen, the correlation coefficient was 0.897.Regions related to MoCA scores in the time-points of 12 weeks were the cerebellum posterior lobe, uvula, tuber, declive and pyramis, the correlation coefficient was 0.991.Conclusion ① Cognitive dysfunction in the subcortical infarction is associated with local white matter fiber integrity changes in the brain, such as Frontal lobe, parietal lobe, insula, limbic, midbrain, medial frontal gyrus, middle frontal gyrus, cingulate gyrus, thalamus, putamen and claustrum. They may affect the recovery of cognitive function.② The voxel-based statistical analysis was richer and fuller than the white matter atlases-based analysis.③ The patients with subcortical infarction would occur cognitive impairment, and the recovery was not obvious within the first three months. In terms of detection of mild cognitive impairment, MoCA scale may be more sensitive than the MMSE scale.④ FA values in the the occipital lobe, lingual gyrus, limbic lobe, posterior cingulate, calcarine_L, cerebellum, precuneus and cuneus showed positive significant correlations with the global cognitive function.⑤ Secondary changes in white matter fibers may be an important cause of cognitive dysfunction after subcortical infarction. Whole brain, voxel-based analysis of DTI can reflect white matter secondary changes fully and accurately, which contributes to the early diagnosis of cognitive impairment in stroke.