Impact of Clinical Variables and Aneurysm Morphology on Hemorrhage Volume and Clinical Outcomes

Neurosurgery 98:394–403, 2026

This study investigates determinants of aneurysmal subarachnoid hemorrhage (aSAH) volume and its effect on early clinical outcomes using objective, semiautomated CT quantification in 200 ruptured intracranial aneurysms. Multivariate analysis identified older age, higher Hunt and Hess score, and bifurcation aneurysm location as independent predictors of larger aSAH volume, while sex (female) correlated with lower volumes.

Outcome analysis stratified by age showed that in patients 18–64 years greater aSAH volume increased risk of delayed cerebral ischemia, clinical vasospasm, and 7-day mortality; in patients ≥65 years larger volume was associated only with 7-day mortality. The authors recommend multicenter studies using objective quantification to validate age-specific clinical implications.

Hemorrhage Volume Predictors: Larger aneurysmal subarachnoid hemorrhage (aSAH) volumes are associated with older age, higher Hunt and Hess (HH) scores at admission, and ruptured aneurysms located at arterial bifurcations, especially the basilar tip; women have lower hemorrhage volumes than men.

Aneurysm Morphology: Aneurysm size, aspect ratio (AR), size ratio (SR), and irregular morphology do not significantly influence aSAH volume, although bifurcation location is a strong predictor of increased hemorrhage volume.

Hemodynamics Over Morphology: Hemorrhage volume appears to be more influenced by cerebral flow dynamics and aneurysm location (bifurcation vs. sidewall) than by traditional morphological parameters such as size or shape.

Age-Dependent Outcomes: In patients aged 18–64 years, larger aSAH volume is linked to increased risk of delayed cerebral ischemia (DCI), clinical vasospasm, and 7-day mortality; in patients ≥65 years, larger volume is only associated with increased 7-day mortality, not DCI or vasospasm.

Elderly Population Specifics: Lower risk of vasospasm and DCI in elderly patients may be due to arteriosclerotic changes and larger cisternal spaces, which allow greater blood accumulation without corresponding clinical symptoms.

Objective Measurement: Use of semiautomated, machine learning-based tools (e.g., MATLAB segmentation) provides more reliable and reproducible quantification of hemorrhage volume compared to subjective grading systems.

Clinical Implications: Objective hemorrhage quantification could improve risk stratification, facilitate personalized treatment, and enhance understanding of blood clearance and outcomes after aSAH.

Research Recommendations: Multicenter studies using objective quantification methods are needed for validation and to refine management strategies for ruptured aneurysms, considering age-specific differences