Efficacy and Safety of Extracranial-Intracranial Bypass Surgery for Posterior Circulation Aneurysms: A Systematic Review and Single-Arm Meta-Analysis

Treating complex posterior circulation aneurysms poses challenges, and extracranial to intracranial (EC-IC) bypass techniques are potential therapeutic options. However, the safety and efficacy of this approach for posterior circulation aneurysms remain unclear. The study's objective was to assess the safety and efficacy of EC-IC bypass in these aneurysms. Adhering to PRISMA guidelines, we conducted a systematic review on EC-IC revascularization for posterior circulation aneurysms. Included studies had at least four patients and reported data on mortality, patency, complications, or clinical outcomes. Favorable clinical outcomes were defined as mRS below 3 or GOS above 3, and complications were any issues related to the bypass procedure. From 3,036 articles reviewed, 22 studies involving 196 patients who underwent 210 EC-IC bypass procedures for posterior circulation aneurysms were selected. The median follow-up period of 14 studies was 31.66 months (6 - 61 months). Final follow-up indicated a high bypass patency rate of 96% [95% CI: 91% - 100%; I2 = 12%], with a mortality rate of 5% [95% CI: 1% - 9%; I2 = 0%]. Additionally, 83% [95% CI: 70% - 96%; I2 = 77%] of patients showed good outcomes at the last follow-up. Complications were observed in 40% [95% CI: 26% - 55%; I2 = 80%]. Heterogeneity was associated with specific studies. EC-IC bypass procedures are a viable treatment option for posterior circulation aneurysms, with high bypass patency rates and favorable clinical outcomes. However, complications, especially neurological deficits, exist. Open revascularization remains essential for neurovascular surgeons dealing with complex aneurysms.