BACKGROUND
Delayed cerebral vasospasm is a feared complication of aneurysmal subarachnoid hemorrhage (SAH).
OBJECTIVE
To investigate the relationship of systemic inflammation, measured using the systemic immune-inflammation (SII) index, with delayed angiographic or sonographic vasospasm. We hypothesize that early elevations in SII index serve as an independent predictor of vasospasm.
METHODS
We retrospectively reviewed the medical records of 289 SAH patients for angiographic or sonographic evidence of delayed cerebral vasospasm. SII index [(neutrophils × platelets/lymphocytes)/1000] was calculated from laboratory data at admission and dichotomized based on whether or not the patient developed vasospasm. Multivariable logistic regression and receiver operating characteristic (ROC) analysis were performed to determine the ability of SII index to predict the development of vasospasm.
RESULTS
A total of 246 patients were included in our study, of which 166 (67.5%) developed angiographic or sonographic evidence of cerebral vasospasm. Admission SII index was elevated for SAH in patients with vasospasm compared to those without (P < .001). In univariate logistic regression, leukocytes, neutrophils, lymphocytes, neutrophil-lymphocyte ratio (NLR), and SII index were associated with vasospasm. After adjustment for age, aneurysm location, diabetes mellitus, hyperlipidemia, and modified Fisher scale, SII index remained an independent predictor of vasospasm (odds ratio 1.386, P = .003). ROC analysis revealed that SII index accurately distinguished between patients who develop vasospasm vs those who do not (area under the curve = 0.767, P < .001).
CONCLUSION
Early elevation in SII index can independently predict the development of delayed cerebral vasospasm in aneurysmal SAH.
Introduction:
The role of neuroinflammation following aneurysmal subarachnoid hemorrhage (SAH) and its relationship to outcome is the subject of many ongoing studies. The proteolytic enzyme, caspase-1, activated by the inflammasome complex, is known to contribute to numerous downstream pro-inflammatory effects. In this study, we investigated caspase-1 activity in the cerebrospinal fluid (CSF) of SAH patients and its association to outcome.
Methods:
SAH patients were recruited from a regional stroke referral center. CSF samples from 18 SAH subjects were collected via an external ventricular drain and obtained within 72 hours of the onset of symptoms. For control subjects, we collected the CSF from 9 patients undergoing lumbar puncture with normal CSF and normal brain MRI. Caspase-1 activity was measured using commercially available luminescence assays. SAH subjects were categorized at hospital discharge into those with good outcomes (Glasgow Outcome Scale, GOS, of 4-5) and poor outcomes (GOS of 1-3). The levels of caspase-1 activity in various groups were analyzed using Mann-Whitney and Pearson correlation tests. Caspase-1 activity was also adjusted by initial severity of bleed using analysis of covariance (ANCOVA).
Results:
Caspase-1 levels from SAH patients were significantly higher than that measured from the control group (mean 1.06x10-2 vs 1.90x10-3 counts per second (CPS)/μl*min), p = 0.0002). Within the SAH group, 10 patients (55.6%) had good outcomes and 8 patients (44.4%) had poor outcomes. Caspase-1 activity was significantly higher in the poor outcome group (mean 1.54x10-2 vs 1.60x10-3 CPS/μl*min), p = 0.0012). Additionally, caspase-1 activity had a statistically significant correlation with GOS score (r = -0.60; p = 0.0100). When adjusted for initial severity of bleed, the difference in caspase-1 activity in good vs. poor outcome remained significant (adjusted mean 7.10x10-3 vs. 2.54x10-2 CPS/μl*min, p=0.004).
Conclusions:
The inflammasome-dependent protein caspase-1 is elevated in CSF early after SAH and higher in those with poor functional outcome. Inflammasome activity therefore may serve as a novel biomarker to predict outcome shortly after aneurysm rupture.
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