A Dynamic MRI Study Of Structure And Function Changes About Primary Motor Cortex After Stroke

Objective The secondary structural damage and functional reorganization of primary motor cortex(M1) in chronic stroke patients affecting motor pathway have been reported. But the spatial relationship between the structural damage region and functional reorganization region and the dynamic changes of neurological function of these two regions are still unclear. We aimed to clarify this issue by collect subcortical stroke patients functional MRI data longitudinally and analyze the data by Voxel-based morphometry(VBM) and resting-state functional MRI technique.Subjects and Methods Thirteen patients experienced subcortical stroke underwent a series of high resolution T1 weighted imaging and resting-state f MRI assessments over a period of half year, i.e., within first week, at 2 weeks, at 1month, at 3months, and 6months after stroke onset. Twelve age- and gender- matched healthy volunteers were recruited as controls while they underwent the same assessments only one time. Firstly, we compared the difference of VBM, ALFF, Re Ho between the chronic stage data of patients and healthy controls. Then, we defined the decreased gray matter volume area of ipsilateral M1 as structural damage region. We defined the increased ALFF and Re Ho area of ipsilateral M1 as functional reorganization region. Secondly, we calculated the resting-state functional connectivity of ipsilateral M1 structural damage region and contralateral M1, the rs FC of ipsilateral M1 functional reorganization region and contralateral M1 respectively. Finally, repeated measures in SPSS was used to analyze the dynamic changes of M1-M1 rs FC of patients. Two sample t test was used to compare the difference of M1-M1 rs FC between patients and healthy controls.Results 1. 7 patients(4 males, 3 females) underwent all 5 times examinations were finally recruited. 10 volunteers(5 males, 5 females) were also recruited as control group. 2. The decreased gray matter volume area and increased ALFF and Re Ho area could be found in ipsilateral M1 of patients. The increased ALFF and Re Ho area were superposed with each other. The gray matter volume area was adjacent to increased ALFF area. 3. The rs FC of ipsilateral M1 structural damage region(decreased gray matter volume area) and contralateral M1 of patients reduced at the first week, and reached lowest point at two weeks after onset. The rs FC began to increase since 1month after onset, and finally higher than normal level. 4. The rs FC of ipsilateral M1 functional reorganization region(increased ALFF area) and contralateral M1 of patients reduced at the first week, and began to increase since 2 weeks after onset. The rs FC increased slowly since 1month after onset, and reached normal level after 6 months.Conclusions: 1. Both the structural damage and functional reorganization region could be found in ipsilateral M1 in chronic subcortical stoke patients affecting motor pathway. 2. The rs FC of ipsilateral M1 structural damage region and contralateral M1 of patients initially reduced,and then increased to higher than normal level. This phenomenon indicated that a kind of functional reorganization could occur in structural damage region. 3. The rs FC of ipsilateral M1 functional reorganization region and contralateral M1 of patients initially reduced,and finally restored to normal level. This phenomenon indicated that different neurological functions could recover vary in degree after stroke.