title: Geometry of saccular cerebral aneurysms not associated with a branch vessel.
abstract: OBJECTIVE
  Saccular cerebral aneurysms located at nonbranching sites are uncommon. Their distribution, morphological features, and presence of a branch vessel or a tiny perforator(s) separate from the aneurysm neck were investigated.
  
  
  METHODS
  From a series of 303 microsurgically clipped saccular cerebral aneurysms, 40 aneurysms were identified at sites not related to a branch vessel.
  
  
  RESULTS
  The distribution of aneurysms at nonbranching sites was internal carotid: 21 of 40 (52.5%); main stem of the middle cerebral artery/secondary branch of the middle cerebral artery: 6 of 40 (15%); anterior cerebral artery: 1 of 40 (2.5%); pericallosal artery: 1 of 40 (2.5%); pericallosal/callosal marginal: 3 of 40 (7.5%); vertebral artery: 1 of 40 (2.5%); posterior cerebral artery: 1 of 40 (2.5%); posterior cerebral artery/secondary branch of the posterior cerebral artery: 1 of 40 (2.5%); anterior inferior cerebellar artery: 1 of 40 (2.5%); and distal posterior inferior cerebellar artery: 1 of 40 (2.5%). Branch vessels were seen in 5 cases, and small perforating vessels were observed in 2 instances.
  
  
  CONCLUSIONS
  Saccular aneurysms occurring at nonbranching sites are uncommon. Their geometry is particularly favorable for flow directed stents and is most amenable to aneurysms located on large-diameter conducting vessels such as the internal carotid, vertebral, and vertebrobasilar vessels. Smaller parent arteries harboring this type of aneurysm will require new technology to maintain patency of these more distal vessels. If endovascular techniques cannot achieve aneurysm sac obliteration, then open craniotomy and aneurysm clipping will provide a satisfactory alternative.
authors.affiliation: Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana. Electronic address: michael.pritz@denlabs.com.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Pritz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015901:Angiography, Digital Subtraction; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D002533:Cerebral Angiography / Q000379:methods; D002536:Cerebral Arteries / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D002560:Cerebrovascular Circulation; D057510:Endovascular Procedures; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D018810:Magnetic Resonance Angiography; D008297:Male; D008866:Microsurgery; D008875:Middle Aged; D018579:Patient Selection; D014057:Tomography, X-Ray Computed; D014654:Vascular Patency; D014711:Vertebral Artery / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D055815:Young Adult
keywords: Cerebral arteries; intracranial aneurysm; saccular aneurysm; treatment