Comparison of Scoring Systems for Ruptured and Unruptured Small Intracranial Aneurysms: A Retrospective Analysis

Abstract

The management of small (≤7 mm) intracranial aneurysms (SIAs) remains challenging owing to the low but non-negligible rupture risk and potential treatment complications.

The objective of this study is to assess and compare the differences in scoring system results between patients with ruptured and unruptured SIAs.

We investigated all patients with ruptured and unruptured SIAs admitted to the Department of Neurosurgery in 2021 and 2022. In the case of patients with subarachnoid hemorrhage, only those with ruptured SIA qualified for the study. The risk of SIAs rupture was estimated using four different scoring systems: PHASES, small intracranial aneurysms of the anterior circulation (SIAAC), unruptured cerebral aneurysm study (UCAS), and the simplified version of the unruptured intracranial aneurysm treatment score (UIATS) by Juvela.

The study included 170 patients (64.7% women). Ruptured aneurysms were associated with higher scores across all systems. Simplified UIATS demonstrated the largest mean difference between group (1.94 ± 2.48 vs. 4.18 ± 2.90; p < 0.001, ΔCI: 1.42–3.06, Cohen's d = 0.84), whereas SIAAC (4.53 ± 2.10 vs. 6.83 ± 2.75; p < 0.001, ΔCI: 1.48–3.13, Cohen's d = 0.95) has shown the highest effect size. No significant size differences were noted between ruptured and unruptured SIAs (p = 0.059). Receiver operating characteristic curve analysis identified SIAAC as the top post hoc rupture status predictor in small aneurysms (AUC = 0.746), outperforming UCAS (AUC = 0.725), simplified UIATS (AUC = 0.710), and PHASES (AUC = 0.636). SIAAC achieved 94% sensitivity and 88% specificity at the optimal cutoff (2.50).

Simplified UIATS and SIAAC may serve as useful tools in decision-making for the treatment of aneurysms ≤7 mm outperforming other, more frequently used scoring systems.