Abstract 92: Cerebral Microbleeds in Transient Ischemic Attack and Minor Cerebrovascular Events

Background: Transient focal neurological episodes (TFNE) can occur in cerebral amyloid angiopathy (CAA) and can mimic transient ischemic attack (TIA). Hypothesis: Risk factors and outcomes of patients with minor stroke or TIA would differ in patients with and without cerebral microbleeds (CMB), including in patients with lobar microbleeds potentially consistent with CAA. Methods: 431 of 510 patients with high-risk TIA (motor or speech deficits > 5 minutes) or minor stroke in the previously reported CATCH (CT and MRI in the triage of TIA and minor cerebrovascular events to identify high risk patients) study underwent baseline MRI. 416 scans with sufficient quality were analyzed for presence and location of CMB and cortical superficial siderosis. Clinical symptoms, baseline characteristics, recurrent TIA or stroke and 90 day modified Rankin scale (mRs) were prospectively collected. Results: CMB were detected in 65/416 (15.6 %), with a predominantly lobar pattern (75.4 %), and superficial siderosis in 11/416 (2.6 %). In a multivariable logistic regression model adjusted for number of risk factors age was associated with presence of CMB (odds ratio (OR) 1.04; 95 % confidence interval (CI) 1.02 - 1.06, P = 0.001). Presence of CMB was not associated with recurrent stroke or TIA (9.2 % vs. 11.1 %, P=0.65) or unfavorable mRS (> 1) at 90 days (20 % vs. 16 %, P =0.42). Superficial siderosis was present in 11/416 (2.6%). 42 patients (10.1 %) fulfilled modified Boston criteria for possible or probable CAA. Presenting symptoms were not different between patients with vs. without possible/probable CAA, when considering either all patients or just those with TIA. Possible/probable CAA was not associated with recurrent stroke or TIA (7.1 % vs. 11.2 %, P = 0.42) or unfavorable mRs (> 1) at 90 days (23.8 % vs. 15.8 %, P = 0.18). Conclusions: CMB in TIA and minor stroke patients are moderately common but do not strongly predict clinical recurrence and or 90-day functional outcome. Clinical presentations for CAA-related TFNE and TIA might be overlapping, suggesting that MRI may be needed to differentiate them.