Cerebrospinal Fluid Hemoglobin to Monitor for Aneurysmal Subarachnoid Hemorrhage Related Secondary Brain Injury

This is an international multicentre observational study to validate cerebrospinal fluid hemoglobin (CSF-Hb) as a monitoring biomarker for aneurysmal subarachnoid hemorrhage related secondary brain injury (SAH-SBI). It is hypothesized that there is an association between the concentration of CSF-Hb and the occurrence of SAH-SBI during the first 14 days after the bleeding (post-SAH). The primary objective of this study is to evaluate the association between ventricular CSF-Hb and SAH-SBI during the first 14 days post-SAH. The secondary objectives are to investigate: * the association between ventricular CSF-Hb and angiographic vasospasms (aVSP), delayed cerebral ischemia (DCI) and delayed ischemic neurological deficits (DIND) during the first 14 days post-SAH, * the accuracy of ventricular CSF-Hb to monitor for aVSP, DCI and DIND during the first 14 days post-SAH, * the association between lumbar CSF-Hb and SAH-SBI, aVSP, DCI and DIND during the first 14 days post-SAH, * the accuracy of lumbar CSF-Hb to monitor for aVSP, DCI and DIND during the first 14 days post-SAH, * the association between baseline measures and CSF-Hb (ventricular and lumbar during the first 14 days post-SAH), * the association between CSF-Hb (ventricular and lumbar during the first 14 days post-SAH) and co-interventions/complications, * the association between CSF-Hb (ventricular and lumbar during the first 14 days post-SAH) and chronic hydrocephalus at 12 weeks follow-up, * the association between CSF-Hb (ventricular and lumbar during the first 14 days post-SAH) and functional outcome at 12 weeks follow-up, * exploratory CSF proteome/metabolome analyses to assess Hb toxicity, inflammation, neuronal, or vascular damage.