When small aneurysms bleed: Functional outcomes and the limitations of size-based risk stratification

Area of Science:

• Neurosurgery
• Neurology
• Vascular Medicine

Background:

• Small intracranial aneurysms (≤5 mm) are often underestimated in clinical significance.
• While rupture risk is studied, post-rupture morbidity severity remains unclear.
• This study investigates aneurysm size as a predictor of functional outcome post-aneurysmal subarachnoid hemorrhage (aSAH).

Purpose of the Study:

• To determine if intracranial aneurysm size independently predicts functional outcome after subarachnoid hemorrhage.
• To assess post-rupture morbidity in patients with small versus large aneurysms.
• To identify independent predictors of poor functional outcome following aSAH.

Main Methods:

• Retrospective cohort study of 421 patients with ruptured saccular intracranial aneurysms.
• Aneurysms stratified by diameter: ≤5 mm vs. >5 mm.
• Primary outcome: functional dependence at 90 days (modified Rankin Scale >2); multivariable logistic regression used.

Main Results:

• 42.3% of ruptured aneurysms were ≤5 mm.
• Larger aneurysms (>5 mm) showed worse discharge functional status, but 90-day outcomes were similar (40.3% vs. 35.4%, P=0.303).
• Aneurysm size was not an independent predictor of poor 90-day functional outcome (P=0.304).

Conclusions:

• Ruptured small aneurysms (<5 mm) yield clinical outcomes comparable to larger ones.
• Findings challenge the notion that small ruptured aneurysms are less clinically significant.
• Aneurysm size alone is insufficient for risk stratification and outcome prediction post-aSAH.