title: The progression of an infundibulum to aneurysm formation and rupture: case report and literature review.
abstract: OBJECTIVE
  Infundibula (IFs) are funnel-shaped symmetrical enlargements that occur at the origins of cerebral arteries and are apparent on 7 to 25% of otherwise normal angiograms. They are frequently considered as normal anatomic variants of no pathogenic significance.
  
  
  METHODS
  We report the case of a ruptured posterior communicating artery aneurysm that had developed at the site of a previously known IF in a 49-year-old hypertensive woman. She had a poor conscious level at admission, with widespread subarachnoid hemorrhage and obstructive hydrocephalus.
  
  
  METHODS
  The patient was immediately ventilated, and an external ventricular drain was inserted. The aneurysm was successfully clipped; however, secondary hemorrhage occurred both before and during craniotomy. She developed marked hypernatremia and subsequently died.
  
  
  CONCLUSIONS
  This is the 11th case of IF-to-aneurysm progression reported. It suggests that in certain cases, serial investigations may be indicated with IFs to detect aneurysm formation and preempt rupture.
authors.affiliation: Department of Neurosurgery, Hurstwood Park Neurological Centre, Princess Royal Hospital, West Sussex, England.
authors.forename: L A
authors.initials: LA
authors.lastname: Marshman
authors.forename: P J
authors.initials: PJ
authors.lastname: Ward
authors.forename: P H
authors.initials: PH
authors.lastname: Walter
authors.forename: R S
authors.initials: RS
authors.lastname: Dossetor
mesh_terms: D017542:Aneurysm, Ruptured / Q000473:pathology*; D002339:Carotid Arteries / Q000473:pathology; D002536:Cerebral Arteries / Q000033:anatomy & histology / Q000473:pathology*; D003399:Craniotomy; D018450:Disease Progression; D004322:Drainage; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D006849:Hydrocephalus / Q000209:etiology / Q000601:surgery; D006955:Hypernatremia / Q000209:etiology; D006973:Hypertension / Q000150:complications; D002532:Intracranial Aneurysm / Q000473:pathology* / Q000601:surgery; D008875:Middle Aged; D012008:Recurrence; D012422:Rupture, Spontaneous; D013345:Subarachnoid Hemorrhage / Q000209:etiology