An infundibulum (plural: infundibula) is a conical outpouching from an artery (usually intracranial), with a broad base narrowing to an apex from which a vessel originates. The most common location for an infundibulum is the origin of the posterior communicating artery (PCOM) from the supraclinoid internal carotid artery. They are common, found in up to a quarter of all cerebral angiograms 1.
The main importance of an infundibulum is that it may be mistaken for a saccular (berry) aneurysm (which is rounded and has the branch at its base). An infundibulum in most cases measures less then 3 mm. Unlike an aneurysm, an infundibulum is not believed to be a risk for rupture and subarachnoid hemorrhage. Only very rarely does an infundibulum eventually develop into an aneurysm 1 and it is generally not thought that an incidental infundibulum requires follow-up unless additional clinical concern is present. Prudent factors that may indicate follow-up include large size, family history of subarachnoid hemorrhage or aneurysm, connective tissue disorders or history of dissection, or an aneurysm elsewhere.
- 1. Marshman LA, Ward PJ, Walter PH, Dossetor RS. The progression of an infundibulum to aneurysm formation and rupture: case report and literature review. Neurosurgery. 43 (6): 1445-8; discussion 1448-9. Pubmed