Bilateral Cerebral Infarcts on Diffusion-Weighted Imaging Predict Etiology of Stroke

Objective: To identify significant etiological differences between patients with bilateral and unilateral Acute Ischemic Stroke (AIS). Background: Limited data suggest bilateral AIS is relatively common, accounting for approximately ten percent of AIS. However, stroke etiology as defined by TOAST criteria has not been well defined for patients with evidence of bilateral AIS on MRI. Methods: Consecutive patients with AIS presenting to our stroke center (July 2008 to July 2013) were retrospectively identified. Patients with bilateral strokes were defined by restriction on DWI/ADC sequences. Univariate analyses and multivariate logistic regression were performed with appropriate test statistics. Results: Of the 641 AIS patient who met inclusion criteria, 74 (11.5%) had bilateral AIS findings on MRI. Compared to patients with unilateral AIS findings, patients with bilateral AIS findings had higher rates of cardioembolic disease (30.1% vs. 21.8%, p<0.001), hypercoagulable state (8.2% vs. 2.0%, p<0.001), and vasculitis (6.9% vs. 1.4%, p<0.001) but did not have significantly different rates of atrial fibrillation by telemetry or ECG (1.4% vs. 5.8%, p=0.111) or ejection fraction < 30% (7.6% vs. 3.5%, p=0.113). Patients with bilateral AIS findings were over seven times as likely to have vasculitis (OR=7.11, 95% CI=2.1083-23.9786, p=0.002) and four times as likely to have a hypercoagulable state (OR=4.69, 95% CI 1.6737-13.1173, p=0.003) as the etiology relative to patients with unilateral stroke, but bilateral AIS findings did not significantly increase the odds of a cardioembolic stroke (OR=1.40, 95% CI 0.7917-2.4715, p=0.248). Conclusions: Cardioembolic etiology of stroke occurs more often in patients with bilateral acute infarction on imaging, but only the odds of vasculitis and hypercoagulable state as etiologies were significantly increased by bilateral acute infarction. Further studies are warranted to understand imaging characteristics of bilateral strokes in regard to etiology. ©2013 The Authors. Published by the JScholar under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/ by/3.0/, which permits unrestricted use, provided the original author and source are credited. Introduction