Early Progressive Changes in White Matter Integrity Are Associated with Stroke Recovery

Abstract

Information on microstructural white matter integrity has been shown to explain post-stroke recovery beyond clinical measures and focal brain damage. Especially, knowledge about early white matter changes might improve prediction of outcome. We investigated 42 acute reperfused ischemic stroke patients (mean age 66.5 years, 40% female, median admission NIHSS 9.5) with a symptomatic MRI-confirmed unilateral middle cerebral artery territory infarction 24-72 h post-stroke and after 3 months. All patients underwent neurological examination and brain MRI. Fifteen older healthy controls (mean age 57.3 years) were also scanned twice. We assessed fractional anisotropy (FA), mean diffusivity (MD), axial (AD), and radial diffusivity (RD). Patients showed significantly decreased white matter integrity in the hemisphere affected by the acute infarction 24-72 h post-stroke, which further decreased over 3 months compared with controls. Less decrease in FA of remote white matter tracts was associated with better stroke recovery even after correcting for infarct location and extent. A regression model including baseline information showed that the modified Rankin Scale and mean FA of the genu of the corpus callosum explained 53.5% of the variance of stroke recovery, without contribution of infarct volume. Furthermore, early dynamic FA changes of the corpus callosum within the first 3 months post-stroke independently predicted stroke recovery. Information from advanced MRI measures on white matter integrity at the acute stage, as well as early dynamic white matter degeneration beyond infarct location and extent, improve our understanding of post-stroke reorganization in the affected hemisphere and contribute to an improved prediction of recovery.

Keywords: Corpus callosum; DTI; Longitudinal; Prediction; Recovery; Stroke.

Fig. 1

Processing flowchart, showing preprocessing steps and lesion registration for each individual. Group analyses were performed using the fMRIB58 FA template

Fig. 2

a Lower white matter integrity in stroke patients compared with controls at post-treatment scan (24–72 h after symptom onset) shown in blue. Note that even in this homogeneous sample, there is substantial variability in the extent of the ischemic lesions ranging from 1 to 14 overlapping lesions presented in orange-yellow. FA, fractional anisotropy. b Significant decreases in white matter integrity (assessed by FA) in patients compared with controls over 3 months post-stroke

Fig. 3

Less decrease in white matter integrity (assessed by FA values) in the genu of the corpus callosum and the left inferior fronto-occipital fasciculus (anterior part). Both remain associated with better stroke recovery (delta NIHSS) after correction for lesion location and extent