Clinical Outcomes and Predictors of Poor Prognosis in Non-aneurysmal Subarachnoid Hemorrhage: A 10-Year Cohort Analysis

Introduction A large majority of spontaneous subarachnoid hemorrhages (SAH) are attributed to aneurysm rupture, though the cause remains unknown in a notable percentage of cases. Non-aneurysmal SAH (naSAH) is generally thought to follow a more benign clinical course than aneurysmal SAH (aSAH); however, similar complications may occur, and poor outcomes are still possible. Given the limited research on naSAH, this study aims to characterize these patients and correlate clinical and radiographic findings with outcomes. Methods A cohort of 149 patients with naSAH was selected from 2014 to 2023. Outcomes were assessed using the modified Rankin Scale (mRS), categorizing results as favorable (mRS 0-2) or unfavorable (mRS 3-6). Descriptive analysis was conducted, dividing the sample into two groups based on blood distribution on computed tomography scan: pretruncal (pnSAH) and non-pretruncal SAH (npnSAH). Associations between variables were tested, and a multivariable logistic regression was performed to identify significant predictors. Results The mean age was 57.54 years, with 79 males (53.0%) and 70 females (47.0%). A favorable outcome was observed in 133 patients (89.3%). Age, chronic hypertension, anticoagulant, and antiplatelet therapy were significant predictors of poor outcome (p < 0.05). A favorable World Federation of Neurosurgical Societies (WFNS) grade (I-III) was recorded in 88.6% of patients and was significantly associated with outcome (p < 0.05). Among the patients with unfavorable outcomes, 87.5% exhibited a npnSAH pattern. Rebleeding was rare, with only one case (0.7%). Acute hydrocephalus was the primary complication observed in naSAH cases (19.5%). Conclusions Patients with a npnSAH pattern were significantly more likely to experience unfavorable outcomes compared to those with a pnSAH pattern. In multivariate regression analysis, WFNS classification, bleeding pattern (pnSAH vs. npnSAH), and acute hydrocephalus were identified as independent predictors of poor outcomes.