Analysis of intrathecal interleukin-6 as a potential predictive factor for vasospasm in subarachnoid hemorrhage

OBJECTIVE: Inflammatory response seems to be one of the relevant pathophysiological aspects for developing vasospasm in subarachnoid hemorrhage. The probable diagnostic value of intrathecal proinflammatory markers is still unclear and is assessed in this study. METHODS: We analyzed daily clinical data and laboratory tests of the cerebrospinal fluid (CSF) of 64 patients with mostly poor-grade subarachnoid hemorrhage during a period of 14 days. Special attention was given to the relationship between the development of vasospasm and the time course of the intrathecal interleukin (IL)-6 concentrations in CSF (IL-6(CSF)). The potential power of IL-6(CSF) for predicting vasospasm was studied. RESULTS: Vasospasm developed in 28.1% of the patients, with a mean onset of 6.4 days after bleeding, and was detected by conventional methods. Patients with vasospasm demonstrated statistically significant higher median values of IL-6(CSF) on Days 4 and 5 (P < 0.05). Most importantly, the increase of IL-6(CSF) preceded the conventional signs of vasospasm. A cut-off value of IL-61C(SF) of at least 2000 pg/ml on Day 4 yielded an 11.72-fold higher relative risk (95% Confidence interval, 2.93-46.60) of developing vasospasm, predicting vasospasm with a sensitivity of 88.9% and a specificity of 78.3%. We found a statistically significant correlation between IL-6(CSF) and delayed cerebral ischemia for Day 7 (P = 0.03). However, there was no correlation with IL-6(CSF) on any other day and outcome. CONCLUSION: IL-6(CSF) seems to be a reliable early marker for predicting vasospasm after subarachnoid hemorrhage on Days 4 and 5 before clinical onset.