Delayed rupture of extradural internal carotid artery aneurysms after flow diverter placement: A systematic...

Delayed rupture following flow diverter (FD) placement in intradural internal carotid artery aneurysms (ICA-Ans) is a well-documented life-threatening complication. Delayed rupture of extradural ICA aneurysms (EICA-Ans) after FD placement is rare, and no comprehensive analysis has been conducted. This study systematically reviewed cases of delayed rupture of EICA-Ans after FD placement and investigated the anatomical features associated with this complication.

We performed a systematic review of the literature and identified 18 cases of delayed rupture after FD placement of EICA-Ans. These were analyzed alongside 2 cases from our institution. As a comparison group, we reviewed 24 patients treated with FD for unruptured EICA-Ans without delayed rupture at our institution. Anatomical features, including the cavernous internal carotid artery (C-ICA) angulation and aneurysm neck location relative to the horizontal segment of the C-ICA, were evaluated.

Among patients with delayed rupture, 15 of 17 aneurysms exhibited severe C-ICA angulation (<90°), and 16 of 17 aneurysms had proximally located necks in the horizontal segment. These features were significantly more frequent in the delayed rupture group than in the nondelayed rupture group (15/17 vs. 5/24; P < 0.001).

Severe C-ICA angulation and proximal aneurysm neck location may increase mechanical stress after FD placement, potentially contributing to a delayed rupture. The identification of high-risk anatomical features can optimize patient selection and procedural strategies.