Objective <p>This study aimed to clarify the prognostic significance of intracranial pressure (ICP) monitoring in patients with aneurysmal subarachnoid hemorrhage (aSAH) who underwent surgical treatment. Specifically, we analyzed clinical demographic data and ICP-related parameters (e.g., optimal cerebral perfusion pressure [CPPopt], ΔCPP) to identify key prognostic indicators, with the ultimate goal of providing evidence to guide and optimize postoperative management strategies for this patient population.</p> Design <p>Retrospective analysis of prospectively collected data.</p> Setting <p>Neurosciences critical care unit of a university hospital.</p> Patients <p>A prospective cohort of 15 aSAH patients undergoing multiparameter monitoring (April 2024–January 2025) and a retrospective cohort of 45 surgically treated aSAH patients (2022–2024) were included.</p> Interventions <p>None.</p> Measurements and main results <p>Demographic data, ICP monitoring results, and Glasgow Outcome Scale (GOS) scores were collected from all patients at one month postoperatively. The absolute difference between the optimal cerebral perfusion pressure (CPPopt) and the 15-min mean cerebral perfusion pressure (CPP) was defined as ΔCPP.​</p> <p>Patients were stratified into two groups based on their GOS scores: the favorable prognosis group (GOS 4–5) and the poor prognosis group (GOS 1–3). Subsequently, statistical analysis was performed to explore the associations between prognostic outcomes and both demographic data (e.g., gender, age, surgical approaches) and monitoring parameters (e.g., pressure reactivity index [PRx], pressure reactivity slope [RAP], ICP, ΔCPP).</p> <p>A retrospective cohort of 52 patients with aSAH — treated at the Second Hospital of the University of South China between 2022 and 2024 — was matched with a prospective cohort at a 1:3 ratio using propensity score matching (conducted via R software). After matching, 45 patients from the prospective cohort were retained as controls. Baseline characteristics were well-balanced between the retrospective (test) group and the prospective (control) group, and the distributions of prognostic outcomes were compared between the two groups.</p> <p>Elevated initial ICP was a strong predictor of poor prognosis (41.33 ± 10.23 vs. 25.89 ± 10.42&#xa0;mm Hg, p = 0.014). In patients with ICP ≥ 25&#xa0;mm Hg, decompressive craniectomy (DC) was associated with a trend toward improved outcomes (Relative Risk [RR] ≈4.8, p = 0.08).​</p> <p>The poor-outcome group exhibited a greater mean ΔCPP compared with the favorable-outcome group (12.88 vs. 10.61, p = 0.033). Hypoperfusion (i.e., cerebral perfusion pressure [CPP] &lt; optimal CPP [CPPopt]) was significantly associated with adverse outcomes (p = 0.038). In contrast, hyperperfusion (i.e., CPP &gt; CPPopt) was not significantly associated with harm (p = 0.084).​</p> <p>Furthermore, patients who underwent ICP monitoring had a higher favorable prognosis rate than those without monitoring (60% vs. 31.1%, p = 0.046).</p> Conclusions <p>First, in the clinical management of aSAH patients, ICP monitoring plays a pivotal role: it not only facilitates surgical decision-making (e.g., selection of decompressive craniectomy) but also optimizes postoperative hemodynamic management strategies tailored to individual patients.​</p> <p>Second, two key factors were identified to predict poor prognosis in aSAH patients: one is the deviation from postoperative CPPopt, among which hypoperfusion is a particularly impactful subtype; the other is elevated initial ICP.​</p> <p>Furthermore, this study confirmed that management guided by multiparameter monitoring significantly improves short-term clinical outcomes in aSAH patients, providing practical evidence for the optimized clinical management of this patient population.</p>