1096 Revascularization Strategies for Complex Posterior Circulation Aneurysms

INTRODUCTION: The management of ruptured complex posterior circulation aneurysms remains challenging. Cerebral bypass techniques combined with endovascular embolization offer a unique multidisciplinary approach. METHODS: We analyzed retrospective data from patients who underwent bypass for posterior circulation aneurysms from January 2016 to July 2023. The data sourced from an IRB-approved, prospectively maintained database included patient demographics, clinical status, aneurysm characteristics, treatments, complications, and neurological outcomes. Fisher’s exact test was performed for categorical variables using JMP Pro 18. RESULTS: 31 patients underwent bypass for posterior circulation aneurysms; most were ruptured (71%), fusiform/dissecting (87%), and involved PICA (48.4%). Suboccipital craniotomies were performed in 64.5% of cases, with intracranial-intracranial (IC-IC) bypass constructs in 48.4%. Interposition grafts were utilized in 41.9%, with DLCFA (descending branch of lateral circumflex femoral artery) being the most common. Aneurysm occlusion was performed via endovascular embolization in 38.7% and proximal clip occlusion in 32.3%. There were 6 cases of treatment-related infarcts. At discharge, the average Glasgow Outcome Scale (GOS) was 3.4 ± 1.1, and the Modified Rankin Scale (mRS) was 3.2 ± 1.7. At follow-up (average 33.1 months), 71.4% of bypasses were patent, and the GOS and mRS improved to 4.5 ± 0.7 and 1.2 ± 1.5 respectively. Good outcomes (mRS=2, GOS=4) occurred in 90% of patients available for follow-up. Better outcomes were associated with the following: unruptured aneurysm (p=0.02), clipping (p=0.005), IC-IC bypass (p=0.02), no treatment-related stroke (p=0.002), and no VP shunt (p=0.02). An example case (STA-DLCFA-PCA bypass and proximal clipping for fusiform basilar aneurysm) with imaging and intraoperative footage is shown. CONCLUSIONS: The multidisciplinary bypass strategies described in this series were effective for the treatment of complex posterior circulation aneurysms with good long-term outcomes. Unruptured aneurysms, IC-IC bypasses, and microsurgical clipping rather than endovascular embolization were associated with better late-term outcome scores.