Reduced severity of strokes in patients with silent brain infarctions

Background: Silent brain infarctions (SBIs), leukoaraiosis (LA), and microbleeds (MBs) are ischaemic silent radiologic abnormalities that act as predictors of subsequent strokes. This study investigated the independent effect of silent radiologic abnormalities on initial stroke severity and short-term outcome.

Methods: A consecutive series of patients who had their first ischaemic stroke within 72 h of symptom onset were included. Demographic and clinical characteristics were collected on admission, and magnetic resonance imaging was performed to evaluate the ischaemic lesion, SBI, LA, and MB. Factors potentially associated with lower initial stroke severity (admission NIH Stroke Scale 0–5) and good short-term outcome (discharge NIH Stroke Scale 0–5, modified Rankin Scale 0–1) were validated by multivariate analysis.

Results: Silent brain infarctions were noted in 82 (45%) of the 182 patients. Although there were no statistically significant differences in stroke subtypes and lesion location, univariate analysis revealed that patients with SBI had reduced stroke severity (P = 0.005) and infarction volume (P = 0.001). After adjusting for covariates, the presence of SBI was independently associated with lower stroke severity and good short-term outcome when the NIH Stroke Scale was used as dependent variable (OR 3.368, 95% CI 1.361–8.332, P = 0.009; OR 3.459, 95% CI 1.227–9.755, P = 0.019, respectively). However, the presence of SBI lost significance when the discharge-modified Rankin Scale was used as dependent variable (P = 0.058).

Conclusion: Amongst silent radiologic abnormalities, SBI was the only predictor of reduced stroke severity and infarct volume. Silent brain infarction deserves more attention in evaluating stroke severity.