Abstract 286: Flow Diversion of PICA and PICA Segment Vertebral Artery Aneurysms

Introduction/Purpose Aneurysms originating from the posterior inferior cerebellar artery (PICA) and the PICA segment of the vertebral artery (VA) are atypical, accounting for only 0.49‐3% of intracranial aneurysms 1 . Traditional treatment has included stent‐assisted coil embolization, proximal occlusion, clipping, bypass, and graft reconstruction 2 . Recently, flow diversion has emerged as a promising treatment option 3‐4 . We report a cohort of patients with aneurysms originating from the PICA and PICA segment of the VA treated with flow diversion. Materials/Methods This retrospective cohort study utilized data from the Neurovascular Quality Index (NVQI) database, a comprehensive repository of pre/peri/post‐procedural details. The database includes information extracted from EMR charts by HIPAA‐trained data entry coordinators. The NVQI database was examined for patients with cerebral aneurysms treated between 07/22/20 and 07/25/24. Patients included were those with unruptured and ruptured saccular and/or fusiform aneurysms originating from the PICA and PICA segment of the VA who were treated with flow diversion. Patient demographics, presenting symptoms, procedural details, peri‐ and post‐ procedural complications (hemorrhage, stroke, seizure, and death), and radiographic and clinical follow‐up data were analyzed. Angiographic follow‐up, typically conducted 6‐months post‐treatment, was evaluated using the O'Kelly‐Marotta 5 (OKM) score, which is a standard system used for aneurysms to assess angiographic outcomes after flow diversion. Results Between 07/22/20 and 07/25/24, 608 patients underwent aneurysm treatment, with 19 (3.1%) having aneurysms originating from the PICA (10) or PICA segment of the VA (9). The cohort was 52.6% male with an average age of 55.8 years (± 12.4). Four patients (21.1%) presented with subarachnoid hemorrhage due to ruptured aneurysms at presentation, while 15 patients (78.9%) had aneurysms that were found unruptured. Regarding aneurysm morphology, 7 were saccular (36.8%), 6 were fusiform (31.6%), and 6 were fusiform dissecting (31.6%). The average maximum transverse dimension of the aneurysm was 7.6 mm (±3.79), and the average parent artery diameter was 3.4/2.8 mm (±0.62/0.74) proximally and distally, respectively. A total of 24 Pipeline Embolization Devices (PEDs) were used to treat 19 aneurysms. In 15 patients, 1 stent was used, in 3 patients, 2 stents were used, and in 1 patient, 3 stents were used. Of these aneurysms, 15 were found unruptured and treated with flow diversion alone, 2 were previously ruptured and initially treated with coil embolization, and 2 acutely ruptured and were treated with urgent flow diversion. Final follow‐up angiography is available for 12 patients (66.7%). Among these, 8 patients (66.7%) showed aneurysm cure (OKM‐D), 3 patients (25%) showed progressive decrease on the OKM scale (C2/C3, <5%) with no plans of further treatment, and 1 patient (8.3%) is planned for further treatment. Seven patients (36.8%) are awaiting 6‐month angiography follow‐up. Complications included stroke in 1 patient (5.3%) and seizure in another (5.3%), with no deaths. Conclusion Flow diversion for aneurysms originating from the PICA and PICA segment of the VA is a reasonable option for many patients. In this series, cure was achieved in 66.7% of patients, with a complication rate of 10.5% and no deaths. This study highlights the safety and efficacy of flow diversion in treating these challenging aneurysms.