Extracranial-Intracranial Bypass for Treatment of Blister Aneurysms: Efficacy and Analysis of Complications Compared with Alternative Treatment Strategies.

OBJECTIVE: Blister aneurysms (BAs) represent a clinical challenge without a consensus treatment strategy. We report our institution's experience with BAs with an emphasis on the use of extracranial-to-intracranial (EC-IC) bypass.

METHODS: Seventeen patients with BAs (88% [15/17] ruptured) were treated with microsurgical techniques (5 clip wrappings, 4 clip ligations, 4 EC-IC bypasses and clip trappings, 2 internal carotid artery ligations [1 combined with clip wrapping], and 2 clip trappings).

RESULTS: Six of 17 patients experienced intraoperative ruptures. There were no intraoperative ruptures among the bypass cases and 75% (3/4) of patients achieved a good neurologic outcome. Further, a literature review was performed to identify all previously reported cases of BAs undergoing clip ligation, clip wrapping, EC-IC bypass/clip trapping, and endovascular therapies, encompassing 246 BA cases across 33 studies. Intraoperative ruptures occurred in 29% of clip ligations (23/79), 27.2% of clip wrappings (6/35), 16.1% of EC-IC bypasses (5/31), and 0% of endovascular treatments. Aneurysm recurrence occurred in 2.97% (3/101) with endovascular therapies to 0% with EC-IC bypass. Mortality was 8.8% for clip ligation/wrapping (10/114), 6.5% for EC-IC bypass (2/31), and 4.0% for endovascular treatments (4/101).

CONCLUSIONS: Endovascular interventions have a favorable procedural safety profile but high rates of retreatment for persistent filling or posttreatment aneurysmal growth. Clip ligation and clip wrapping techniques have lower retreatment rates but slightly higher intraoperative risk. EC-IC bypass can safely provide definitive aneurysm securement and should be considered as a first-line therapy for BAs at high-volume bypass centers.