Abstract WP19: Diaschisis Of The Blood-brain Barrier

Abstract

Background: Focal ischemia is thought to have global effects on the brain. Chronic cerebrovascular disease is associated with blood-brain barrier (BBB) disruption. We aimed to determine if ischemic stroke has a remote effect on the BBB. Methods: Patients with acute ischemic stroke who were imaged with MR perfusion weighted imaging (PWI) on presentation and again 24 hours later were included in the study. PWI source images were used to measure BBB disruption as a percentage of the signal that is due to gadolinium leakage. BBB was averaged within a region of interest (ROI) consisting of supratentorial white matter (WM) contralateral to the ischemic stroke. The ROI was defined using a group-averaged diffusion tensor imaging (DTI) fractional anisotropy map. For infratentorial strokes the ROI consisted of bilateral supratentorial WM. For bilateral strokes, the ROI consisted of WM in the less affected hemisphere after removal of the infarct. Segmentation algorithms were used to define infarct volume in mL on DTI at 24 hours and WM hyperintensity volume (WMHvol) on the initial FLAIR image. Average percent BBB disruption was compared with age, baseline modified Rankin scale (mRS), NIHSS, stroke volume, and WMHvol using linear regression. Results: 44 patients were included with a median age of 74, 39% female. Median NIHSS was 4; mean stroke volume was 10 mL. The baseline mRS ranged from 0-3 with a median of 0. The median BBB was 0.86% (IQR:0.72%-1.09%). Higher average BBB disruption measured in the WM remote from the acute stroke was associated with larger stroke volumes (p=0.006, r 2 =0.17, beta 0.410, CI:0.003-0.018), larger WMHvol (p<0.001, r 2 =0.26, beta 0.51, CI: 0.10-0.32), and higher NIHSS (p=0.039, r 2 =0.01, beta 0.312, CI:0.002-0.064) but not with age (p=0.447), sex (p=0.729), or baseline mRS (p=0.093). In multiple linear regression stroke volume (p=0.008) and WMHvol (p<0.001) were independently associated with remote disruption of the BBB but not NIHSS (p=0.684). Conclusions: Focal ischemia resulted in a proportional disruption of the BBB in the WM remote from the acute lesion. This effect was independent of the severity of WMHvol, a measure of cerebral small vessel disease. These findings support the concept of ischemic stroke having global effects on the brain.