Abstract 118: PICA and PICA Segment Vertebral Artery Aneurysms Treated with Flow Diversion: A Case Series

Introduction/Purpose Aneurysms originating from the posterior inferior cerebellar artery (PICA) and the PICA segment of the vertebral artery (VA) are atypical, comprising 0.49‐3% of intracranial aneurysms. 1 Previous treatments include stent‐assisted coil embolization, proximal occlusion, clipping, bypass, and graft reconstruction. 2 Recently, flow diversion has emerged as a promising treatment option. 3‐4 This study reports on a cohort of patients with aneurysms 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 treated for cerebral aneurysms between 07/22/20 and 07/10/25. Included were patients with unruptured and ruptured aneurysms originating from the PICA and PICA segment of the VA who were treated with flow diversion. Demographics, symptoms, procedural details, complications, and radiographic and clinical follow‐up data were then analyzed. Angiographic follow‐up, conducted approximately six months post‐treatment, was evaluated using the O’Kelly‐Marotta (OKM) scale 5 to assess angiographic outcomes after flow diversion. Results Between July 22, 2020, and July 10, 2025, 706 patients underwent aneurysm treatment, with 22 (3.12%) having aneurysms from the PICA (11) or PICA segment of the VA (11). The cohort was 54.5% male with an average age of 57.7 years (± 12.2). Among them, 31.8% were smokers and 81.8% had hypertension. Most aneurysms were unruptured at treatment (77.3%) and 36.4% were found asymptomatic. Common symptoms included headache (50.0%), dizziness (18.2%), numbness (9.1%), and ataxia (9.1%). Subarachnoid hemorrhage was present in 22.7% of cases. Aneurysms were saccular (40.09%), fusiform (22.7%), and fusiform dissecting (36.4%). The average maximum transverse dimension was 7.63 mm (±3.67), and the average parent artery diameter was 3.4/2.9 mm (±0.62/0.67) (proximal/distal). 28 pipeline stents were used to treat 22 aneurysms. Of these, 17 were incidentally found, 2 were previously ruptured and treated with coil embolization, and 3 acutely ruptured and were treated urgently with flow diversion. Final follow‐up imaging was available for 20 patients (95.2%). Among them, 17 patients (85.0%) showed aneurysm cure (OKM‐D), 3 patients (15.0%) showed progressive decrease on the OKM scale (C2/C3, <5%) with no plans of further treatment, and 1 patient (5.0%) required retreatment and resulted in aneurysm cure. Complications included stroke in 1 patient (4.5%), seizure in 2 patients (9.1%), and vasospasm in 3 patients (13.6%), with no deaths reported. Conclusion Flow diversion for PICA and PICA segment of the VA aneurysms is feasible and safe. In this series, radiographic cure was achieved in 85.0% of patients with follow‐up imaging, with a complication rate of 18.2%. This study highlights the effectiveness and safety of flow diversion in treating these challenging aneurysms.