Flow Diversion of Posterior Circulation Cerebral Aneurysms: A Single-Institution Series of 59 Cases

Background: Posterior circulation cerebral aneurysms are at higher risk of rupture and are more symptomatic than those in the anterior circulation. Existing treatments carry significant morbidity. Early reports of flow diversion for posterior circulation aneurysms have suggested high complication and low occlusion rates.

Objective: To report safety and efficacy of flow diversion with the pipeline embolization device (ev3, Medtronic Inc, Dublin, Ireland) for aneurysms located throughout the posterior circulation.

Methods: A prospective, institutional review board-approved database was analyzed for all patients with posterior circulation aneurysms treated by flow diversion at our institution.

Results: Fifty-nine embolization procedures were performed on 55 patients. Average aneurysm size was 9.4 mm. Morphology was saccular (45%), fusiform (29%), or dissecting/pseudo-aneurysms (25%). Sixty-two percent of aneurysms arose along the vertebral artery. There were 7 mid-basilar (13%) and 7 basilar apex (13%) aneurysms. Procedural success was 98%; 1 Pipeline embolization device was placed in 85%; and coiling was performed in 17% of cases. There were 5 major complications (8%), all strokes. Patients with major stroke had modified Rankin Scale score at last follow-up of 1, 3, 4, 6, and 6 (2 mortalities). There were zero intracerebral or subarachnoid hemorrhages. No variable predicted complications on univariate or multivariate analysis. Follow-up digital subtraction angiography was performed for 43 patients (78%). Complete occlusion was 68% at 6 mo and 78% at 12 mo. Average follow-up was 11.8 mo. Fusiform or dissecting morphology and large or giant aneurysm size were predictors of aneurysm persistence at 6 mo on multivariate logistic regression.

Conclusion: This is a large single-institution series of Pipeline (Medtronic Inc) for posterior circulation aneurysms and demonstrates acceptable safety and effectiveness in these challenging cases.