title: Microneurosurgical management of internal carotid artery bifurcation aneurysms.
abstract: BACKGROUND
  Internal carotid artery bifurcation aneurysms form 2% to 9% of all IAs. They are more frequent in younger patients than other IAs. In this article, we review the practical microsurgical anatomy, the preoperative imaging, surgical planning, and the microneurosurgical steps in the dissection and the clipping of ICAbifAs.
  
  
  METHODS
  This review and the whole series on IAs are mainly based on the personal microneurosurgical experience of the senior author (JH) in 2 Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland.
  
  
  RESULTS
  These 2 centers have treated more than 11 000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients with 4253 IAs, 831 (28%) patients had altogether 980 ICA aneurysms, of whom 137 patients had 149 (4%) ICAbifAs. Ruptured ICAbifAs, found in 78 (52%) patients, with median size of 8 mm (range, 2-60 mm), were associated with ICH in 15 (19%) patients. Ten (7%) ICAbifAs were giant (> or = 25 mm). Multiple aneurysms were seen in 59 (43%) patients. The ICAbifAs represented 18% of all IAs ruptured before the age of 30 years.
  
  
  CONCLUSIONS
  The main difficulty in microneurosurgical management of ICAbifAs is to preserve flow in all the perforators surrounding or adherent to the aneurysm dome. This necessitates perfect surgical strategy based on preoperative knowledge of 3D angioarchitecture and proper orientation during the microsurgical dissection.
authors.affiliation: Department of Neurosurgery, Helsinki University Central Hospital, 00260 Helsinki, Finland.
authors.forename: Martin
authors.initials: M
authors.lastname: Lehecka
authors.forename: Reza
authors.initials: R
authors.lastname: Dashti
authors.forename: Rossana
authors.initials: R
authors.lastname: Romani
authors.forename: Ozgür
authors.initials: O
authors.lastname: Celik
authors.forename: Ondrej
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authors.lastname: Navratil
authors.forename: Leena
authors.initials: L
authors.lastname: Kivipelto
authors.forename: Riku
authors.initials: R
authors.lastname: Kivisaari
authors.forename: Hu
authors.initials: H
authors.lastname: Shen
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ishii
authors.forename: Ayse
authors.initials: A
authors.lastname: Karatas
authors.forename: Hanna
authors.initials: H
authors.lastname: Lehto
authors.forename: Jouji
authors.initials: J
authors.lastname: Kokuzawa
authors.forename: Mika
authors.initials: M
authors.lastname: Niemelä
authors.forename: Jaakko
authors.initials: J
authors.lastname: Rinne
authors.forename: Antti
authors.initials: A
authors.lastname: Ronkainen
authors.forename: Timo
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authors.lastname: Koivisto
authors.forename: Juha E
authors.initials: JE
authors.lastname: Jääskelainen
authors.forename: Juha
authors.initials: J
authors.lastname: Hernesniemi