Interleukin 6 in the Cerebrospinal Fluid As a Biomarker for Onset of Vasospasm and Ventriculitis After Severe Subarachnoid Hemorrhage

Objective: The aim of the study was to investigate the diagnostic potential of interleukin 6 (IL-6) and other soluble biomarkers in serum and cerebrospinal fluid (CSF) for early diagnosis of cerebral vasospasm (cVS) and external ventricular drain-associated ventriculitis (VC) and to separate these conditions from aneurysmal subarachnoid hemorrhage (aSAH) without further complication (SAH).

Methods: The concentrations of serum biomarkers and markers in the CSF were collected in 63 consecutive patients with aSAH and external ventricular drainage. Arithmetical means and standard deviations, area under the curve (AUC), cutoff values (C-OFF), sensitivity (SE), and specificity (SP) were calculated for markers and their correlation with SAH, cVS, and VC.

Results: Clinical courses included 27 patients with cVS, 17 with VC, and 19 with SAH. Mean ± standard deviationIL-6 values were 7588 ± 4580 pg/mL at onset of VC and 4102 ± 4970 pg/mL for cVS and higher than 234 ± 239 pg/mL in SAH (P < 0.001). IL-6 showed excellent diagnostic potential for differing between VC and SAH (AUC, 1.00; C-OFF, 707; SE, 100%; SP, 100%), and a moderate diagnostic potential for differing VC from cVS (AUC, 0.757; C-OFF, 3100 pg/Ml; SE, 86.7%; SP, 70.6%). The concentration of IL-6 within the cVS group was significantly increased compared with SAH (AUC, 0.937; C-OFF, 530 pg/mL; SE, 87.5%; SP, 91.7%).

Conclusions: IL-6 is increased after aSAH in patients with cVS or VC. Patients with a IL-6 level higher than a C-OFF of 3100 pg/mL have an increased likelihood for VC; patients with IL-6 levels between 530 and 3100 pg/mL have an increased posttest probability for cVS.