Infundibular Dilations and Subarachnoid Hemorrhage: to Treat or Not to Treat?

BACKGROUND: Infundibular dilations are funnel-shaped widenings at the origin of a cerebral artery, most commonly the posterior communicating artery. Controversy exists as to whether an infundibulum represents a normal anatomic variant or a lesion with the potential for rupture and subarachnoid hemorrhage (SAH). METHODS: We reviewed all reported cases of infundibular dilations and SAH in the world literature and present an illustrative case. RESULTS: Most infundibula in the context of SAH were associated with an aneurysm either on or near an infundibulum. However, there have been 7 reports in which the infundibulum could have been the primary site of rupture and no associated aneurysm was identified. Close review reveals significant limitations of those 7 reports. CONCLUSIONS: The literature, and our own experience, do not support the treatment of infundibula, even in SAH patients. Treatment should be directed toward an associated aneurysm, not the infundibulum.