An Early Increase of Blood Leukocyte Subsets in Aneurysmal Subarachnoid Hemorrhage Is Predictive of Vasospasm

Objective: Vasospasm is a severe complication in patients with aneurysmal subarachnoid hemorrhage (aSAH) and cannot be reliably predicted. Its pathophysiology remains elusive with the current body of evidence suggesting inflammation as one of the main driving forces. We here aimed to analyze circulating immune cell subsets over time in patients with aSAH with or without vasospasm. Methods: We performed a prospective observational study recruiting patients with spontaneous aSAH. Peripheral blood withdrawn at pre-specified time-points after aSAH, day 0, days 3-4, 6-8, 10-11, 13-15, and 18-21. Flow cytometry analysis, cell blood counts, and laboratory and diagnostic parameters were performed. Patients were monitored by transcranial Doppler for vasospasm as well as by advanced imaging and divided into a group with (VS) and without vasospasm VS (NVS). Results: We included 42 patients for study analysis, 21 VS and 21 NVS. An early significant increase at day 0 in platelet, leukocyte, neutrophil, lymphocyte, NK lymphocyte, monocyte, and CD 14++ CD16- DR+ monocyte counts was found in patients with later ensuing vasospasm. The early differences in platelets, leukocytes, lymphocytes, and NK lymphocytes remained significant on multivariate analysis. Conclusions: An early increase of immune cellular subsets in aSAH may contribute to predict VS.