Interleukin-6 Levels in Cerebrospinal Fluid and Plasma in Patients with Severe Spontaneous Subarachnoid Hemorrhage

Abstract

Inflammatory processes play a key role in the pathophysiology of subarachnoid hemorrhage (SAH). This study evaluated whether different temporal patterns of intrathecal and systemic inflammation could be identified in the acute phase after SAH. The intensity of the inflammation was also assessed in clinical subgroups. Cerebrospinal fluid (CSF) and blood samples were collected at days 1, 4, and 10 after ictus in 44 patients with severe SAH. Interleukin-6 (IL-6) was analyzed by a routine monoclonal antibody-based method. Median IL-6 values for each day were calculated. Day 4 IL-6 values were compared in dichotomized groups (age, sex, World Federation of Neurosurgical Societies [WFNS] grade, Fisher scale grade, outcome, vasospasm, central nervous system infection and systemic infections). CSF IL-6 levels were significantly elevated from day 1 to days 4 and 10, whereas plasma IL-6 showed a different trend at lower levels. Median CSF IL-6 concentrations for days 1, 4, and 10 were 876.5, 3361, and 1567 ng/L, whereas plasma was 26, 27.5, and 15.9 ng/L, respectively. No significant differences in CSF concentrations were observed between the subgroups, with the most prominent one being in day 4 IL-6 in the WFNS subgroups (grades 1-3 vs. 4-5, 1158.5 vs. 5538 ng/L; P= 0.056). Patients with systemic infection had significantly higher plasma IL-6 concentrations than patients without infection (31 vs. 16.05 ng/L, respectively; P= 0.028). Distinctly different inflammatory patterns could be seen intrathecally compared with the systemic circulation. In plasma, a significant difference in the intensity of the inflammation was seen in cases with systemic infection. No other subgroup showed statistically significant differences.