Abstract
BACKGROUND: The rupture of an intracranial aneurysm, resulting in aneurysmal subarachnoid hemorrhage (aSAH), constitutes a devastating neurological event marked by an abrupt clinical onset and high morbidity and mortality rates. Controlled lumbar drainage following aSAH has been associated with improved neurological outcomes; however, the underlying mechanisms remain poorly understood. This study aims to characterize the lumbar and cranial cerebrospinal fluid (CSF) compartments and contrast these with serum laboratory test findings, providing a foundational framework for future investigations into the mechanisms by which lumbar drainage facilitates neurological recovery. METHODS: We retrospectively included patients with aSAH for whom CSF specimens were available. Baseline demographic data, serum laboratory test results, and CSF findings were collected following the hemorrhagic event. A CSF infection was defined as a positive microbiological culture result. RESULTS: We included 454 patients, with a total of 7,176 serum samples and 1,911 CSF samples. All patients showed an initial increase in acute-phase protein levels, with a decline afterward, and these dynamics revealed a significant effect of lumbar drainage. Lower C-reactive protein (CRP) levels were observed when using a lumbar drain (p < 0.001). Furthermore, CRP levels peaked earlier and consecutively declined earlier with the use of lumbar drains (p < 0.001). Similarly, leukocyte levels were higher in patients without lumbar drainage (p = 0.002). The majority of blood cells were detected in the lumbar CSF compartment. Notably, the differences between the lumbar and ventricular CSF compartments persisted for up to five days post hemorrhage. CONCLUSIONS: Ventricular and lumbar CSF compartments exhibit significant differences within the first days following aSAH. These findings suggest that blood cell accumulation in the lumbar compartment may contribute to post-aSAH inflammatory processes. Accordingly, the source of CSF samples should be carefully considered to ensure accurate interpretation and to guide therapeutic decision-making in the management of aSAH.