title: Evolution from an infundibulum of the posterior communicating artery to a saccular aneurysm.
abstract: BACKGROUND
  An infrequent case of a de novo aneurysm formation originating from an infundibulum at the origin of the posterior communicating artery (PcomA) is presented. The aneurysm developed within 7 years in a patient who initially presented with subarachnoid hemorrhage (SAH) from a saccular aneurysm of the vertebral artery.
  
  
  METHODS
  A 43-year-old female patient was admitted to our hospital on 16th June 2000 after an acute onset of massive occipital headache. A computed tomography (CT) scan showed a subarachnoid hemorrhage (SAH) around the brainstem and 4-vessel angiography revealed an aneurysm originating from the V4 segment of the right vertebral artery (VA) as the cause of the SAH. A small aneurysm at the basilar artery (BA)/superior cerebellar artery (SCA) bifurcation was also found. Injection of the left internal carotid artery (ICA) showed a diffuse enlargement at the origin of the left PcomA, which at this time was considered to be a so-called infundibulum. The VA aneurysm was treated by coil occlusion. Follow-up digital subtraction angiography (DSA) in 2005 showed a de novo aneurysm formation at the VA junction, again treated by coil occlusion. The PcomA infundibulum at the left ICA was not examined. Follow-up angiography performed in 2007 revealed a saccular de novo aneurysm of the left ICA arising from the origin of the left PcomA with a maximum diameter of 12 mm. Coil occlusion of the PcomA aneurysm was subsequently carried out.
  
  
  CONCLUSIONS
  Infundibular widening of cerebral arteries can develop into true aneurysms. Mid-term and long-term follow-up MRI (e.g., in yearly intervals) is advised for infundibula with a diameter of 3 mm or more. In patients with other aneurysm(s), with a documented de novo aneurysm formation or with a familial occurrence of aneurysms, the risk of evolution of an infundibulum to a saccular aneurysm may be increased and follow-up should be even more stringent.
authors.forename: S
authors.initials: S
authors.lastname: Fischer
authors.forename: N
authors.initials: N
authors.lastname: Hopf
authors.forename: H
authors.initials: H
authors.lastname: Henkes
mesh_terms: D000328:Adult; D015901:Angiography, Digital Subtraction; D002340:Carotid Artery Diseases / Q000175:diagnosis / Q000628:therapy; D002343:Carotid Artery, Internal; D002533:Cerebral Angiography; D018450:Disease Progression; D004621:Embolization, Therapeutic; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000628:therapy; D012008:Recurrence; D019233:Retreatment; D013345:Subarachnoid Hemorrhage / Q000175:diagnosis / Q000628:therapy; D014057:Tomography, X-Ray Computed; D014711:Vertebral Artery