399 Infundibulum Study: A Retrospective Analysis of Cerebral Vascular Infundibula. An Analysis on Growth and Its Significance at an Australian Tertiary Neurosurgical Centre

Abstract

INTRODUCTION: Debate exists regarding the natural history of cerebral infundibula. Pre-aneurysmal lesions and benign anatomical variants have both been proposed. To date there are no large cohort studies defining natural history. METHODS: Retrospective surveillance infundibula were undertaken in a single tertiary cerebrovascular centre. All Infundibula diagnosed on either MRA, CTA or DSA and followed up for 5 years were eligible for inclusion. Radiological and demographic characteristics were recorded at baseline. Infundibula growth, rupture and aneurysmal formation were outcomes of interest. Kaplan Meir curves were used to assess variables of interest with respect to time on surveillance. Groupwise comparison as conducted via Fischer exact testing. RESULTS: 420 cerebral infundibula were followed prospectively, across 402 patients over 2418 infundibula-years. Eleven (2.62%) grew on surveillance, and three (0.7%) formed de-novo aneurysms. Median time to growth was 85 months (36-263) and median time to aneurysm formation was 112 months (96-142). Of the Infundibula that grew, the proportion that were male sex was significant higher compared to those that did not (p < 0.007). Of the Infundibula that grew in surveillance, 2/11 (18.2%) formed aneurysms (p = 0.001). With respect to Kaplan Meir analysis, male sex remained a significant predictor of growth (p = 0.007) and growth on surveillance (p < 0.001) remained a significant predictor of aneurysm formation. CONCLUSIONS: Growing infundibula are high risk of forming aneurysms and warrant ongoing surveillance.