Normanchester: Here is a link that describes the differences between an infundibulum and an aneurysm. Dr. Chouddhri says an infundibulum is a "fake aneurysm." I happened upon this link when I was diagnosed with an aneurysm 2 years ago. Kudos to your neuro doc that he called it out for what it was. On this video Dr. Chouddhri states that patients are referred to him for aneurysm treatment but he finds when he personally reviews their angiograms that they actually only have an infundibulum.