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

Background: Saccular aneurysms of the proximal A1 segment (SAPA₁) 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 SAPA₁ 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 SAPA₁ (average age 53.8±9.6 years, 9 women). The SAPA₁ 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 (PA₁FO) 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 PA₁FO 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. PA₁FO, when collateralization permits, appears to be a reliable therapeutic alternative offering favorable long term outcomes.