Abstract
Sixty-seven patients with first acute ischemic stroke onset between 3 to 7 days and 25 age- and sex- matched controls were analyzed for the performance of a resting-state functional MRI to investigate whether the functional connectivity (FC) of the motor network in acute ischemic stroke is independently associated with functional outcomes. The FC of cortical motor network and default mode network was analyzed. The FC was compared between controls, patients with favorable outcomes (modified Rankin Scale, mRS ≤1), and patients with unfavorable outcomes (mRS ≥2) at 3 months. Of the 67 patients, 23 (34%) exhibited unfavorable outcomes. In multivariate analysis, the FC between ipsilesional primary motor cortex (M1) and contralesional dorsal premotor area (PMd) ≤0.63, were independently associated with unfavorable outcomes (odds ratio = 6.32, P = 0.032), whereas the FC of default mode network was not different between groups. The interhemispheric FC of the motor network is an independent predictor of functional outcomes in patients with acute ischemic stroke.
Highlights
Ischemic stroke is a leading cause of disability in developed countries
The functional connectivity (FC) matrices of motor network by using dynamic Global Signal Regression (dGSR) are presented in the Fig. 9, and the corresponding analysis of variance (ANOVA) P value matrices of the 3-group comparison are presented in the Fig. 10
Most previous studies regarding functional magnetic resonance imaging (fMRI) in stroke enrolled patients at 2 weeks or later after stroke onset with about 20 patients in each study[11,12,13,14,15,16,17,18,19,20,21,22,23], so it was not possible to test the predictive power of FC by using multivariate analyses
Summary
Ischemic stroke is a leading cause of disability in developed countries. More than half patients with ischemic stroke can not go back to work despite months of aggressive treatment and rehabilitation[1]. Stroke severity, lesion volume, or lesion location are important factors influencing functional outcome; but none of them could be intervened effectively, and mild stroke severity does not guarantee a favorable outcome[2] Several factors, such as uncontrolled hypertension, hyperglycemia, and inflammation, have been proposed to predict unfavorable functional outcomes[3,4,5]. Resting-state functional magnetic resonance imaging (fMRI) is a valid research tool for stroke[10] With this technique, the functional connectivity (FC) represents the synchrony of intrinsic blood oxygen level-dependent (BOLD) signal fluctuations among different brain regions. Previous studies had relatively small subject number in each study, and it is difficult to eliminate the influence of confounding factors of stroke outcome Another issue is the potential hemodynamic lag in the hemisphere with ischemic lesions, which may affect the measurement of FC24,25. We hypothesized that the FC of the motor network in patients with acute ischemic stroke is worse than health population, and the FC at acute stage of stroke is predictive of the functional outcomes
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