Indirect flow diversion for the treatment of saccular posterior inferior cerebellar artery aneurysms: An 11-year single-center retrospective study.

IntroductionPosterior inferior cerebellar artery (PICA) aneurysms are rare but associated with high rupture rates and significant morbidity and mortality. Both surgical and endovascular treatments can be technically challenging. This study evaluates the efficacy and safety of indirect flow diversion using flow-diverting stents (FDS) deployed in the vertebral artery, covering the PICA origin.Patients and methodsWe retrospectively reviewed all patients treated at our center between March 2013 and March 2024 for proximal saccular PICA aneurysms using FDS deployed in the V4 segment of the vertebral artery. Clinical and aneurysm characteristics, procedural details, imaging follow-up, and clinical outcomes were collected and analyzed.ResultsFourteen patients were treated, including eight (57%) as first-line procedures. Adequate aneurysm occlusion (O'Kelly-Marotta grade C or D) was achieved in 50% of cases at last follow-up (median: 38.5 months (interquartile range: 29.5-48.0; total: 47.6 person-years)). No hemorrhagic or clinically significant ischemic events occurred. One asymptomatic ischemic lesion (7%) was detected on magnetic resonance imaging. No aneurysm growth or rupture was observed during follow-up. PICA patency was preserved in all cases, with non-significant narrowing in two patients. Neointimal hyperplasia was observed in six patients (43%).ConclusionIndirect flow diversion with vertebral artery FDS coverage of the PICA origin appears to be a technically feasible and safe strategy. Although complete occlusion rates may be lower than in other anatomical locations, the long-term stability and low complication rates support its use as a therapeutic option in selected cases.