Endovascular management of saccular aneurysms of the proximal A1 segment: technical particularities and long term outcomes.

Background: Saccular aneurysms of the proximal A1 segment (SAPA) are rare, but their treatment is challenging and scarcely described in the literature. We report the immediate and long term outcomes of their endovascular management.

Methods: We retrospectively analyzed all consecutive SAPA cases treated endovascularly at our center between 2003 and 2023. Per procedural complications and radioclinical outcomes were prospectively recorded.

Results: Among 2468 patients followed up for aneurysms, 12 (0.49%) had an SAPA (average age 53.8±9.6 years, 9 women). The SAPA averaged 3.3 mm, all posteriorly oriented. Ten were ruptured (83.3%). Initial treatments included conventional coiling or balloon assisted coiling (CC/BAC) for nine aneurysms, and proximal A1 segment focal occlusion (PAFO) for three. Initial occlusion was deemed satisfactory in all instances: total occlusion in eight cases (67%) and subtotal occlusion in four cases (33%). Four aneurysmal perforations occurred (33%), all during CC/BAC on ruptured aneurysms. Over a 10.2 year average follow-up, six recanalizations (50%) were noted, all after initial CC/BAC: three were early (≤14 days), with one causing fatal rebleeding. No recanalizations after PAFO was observed (five in total, two as a complement after CC/BAC). Favorable clinical outcomes (modified Rankin Scale score of 0-2) were seen in 91% of cases (11/12) at the last follow-up.

Conclusions: Selective coiling of the aneurysmal sac is technically difficult due to their small size and the complex microcatheterization pathway. This method presents a significant risk of aneurysmal perforation, especially in ruptured cases, and a high rate of recanalization. PAFO, when collateralization permits, appears to be a reliable therapeutic alternative offering favorable long term outcomes.