Microparticles in aneurismal subarachnoid hemorrhage: role in acute and delayed cerebral ischemia

Abstract

Background: Microthrombosis has been demonstrated in early and delayed cerebral ischemia after aneurismal subarachnoid hemorrhage (aSAH). Markers of coagulation activation as microparticles (MPs) are an established risk factor for thrombosis. We tested the hypothesis that levels of microparticles might correlate with (i) aSAH severity (ii) early cerebral ischemia (ECI) and (iii) delayed cerebral ischemia (DCI). Methods: Consecutive aSAH patients (age 18-80) admitted to our department between November 2011 and September 2012 were included in the study. Total Mps (AnnexinV+), platelet Mps (PLTMPs, AnnexinV+/CD41+), tissue factor MPs (TF-MPs, AnnexinV+/ CD142+), and endothelial MPs (E-MPs, AnnexinV+/CD144+) were measured by flow cytometry in venous blood samples, obtained at early (<3 day) and delayed phase (7-10 days). Multi-parameter MRI was performed to evaluate ischemic damage and vasospasm at the same timepoints. Levels of MPs were evaluated comparing patients according to (i) SAH severity (World Federation of Neurological Surgeons score) (ii) ECI severity and (iii) occurrence of delayed complications (vasospasm and DCI). Results: Twenty-five patients (age 57 ± 12 years) were included in the analysis. Overall increased levels of MPs were observed at early phase after aSAH when compared to controls (334, IQR 80-775 vs. 64 IQR 40-147, P = 0.0024). In the early phase no significant differences in MPs level were observed in patients with different aSAH severity (MPs tot 436, IQR 76-918 vs. 313 and IQR 83-638 respectively, P = 0.56). Interestingly patients with most severe ECI (MPs tot 95, IQR 47-178 and 69, IQR 28-95 vs. 37 IQR 34-39, Kruskal-Wallis test P = 0.19) and DCI (MPs tot 131, IQR 74-281 and 53 IQR 35-361 vs. 46 IQR 19-117, Kruskal-Wallis test P = 0.29) showed the highest values of MPs, but this trend did not reach statistical significance, probably because of the the still small sample size small number of patients included in the study. Conclusions: Microparticles and microthrombosis may increase the severity of early and delayed ischemic damage after aneurismal SAH. A larger number of patients are required to confirm this preliminary observation.