title: Microneurosurgical management of aneurysms at A4 and A5 segments and distal cortical branches of anterior cerebral artery.
abstract: BACKGROUND
  Aneurysms originating distal to the A3 segment of the ACA, located on the A4 and the A5 segments or the distal cortical branches of the ACA (AdistAs) are rare, forming about 0.5% of all IAs. There are only few reports on management of AdistAs. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of AdistAs.
  
  
  METHODS
  This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (J. H.) 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 10000 patients with IAs since 1951. In the Kuopio Cerebral Aneurysm Database of 3005 patients and 4253 IAs, there were 26 patients carrying 26 AdistAs, forming 0.9% of all patients with IAs, 0.6% of all IAs, and 2% of all ACA aneurysms. A total of 10 (38%) patients presented with ruptured AdistAs, with ICH in 4 (40%) and IVH in 2 (20%); 16 patients (62%) had multiple aneurysms.
  
  
  CONCLUSIONS
  AdistAs are small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs. Our data suggest that AdistAs rupture at smaller size than IAs in general. The challenge is to locate the aneurysm inside the interhemispheric fissure and to clip the neck adequately without obstructing branching arteries at the base. Unruptured AdistAs also need microneurosurgical clipping even when they are small.
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: Juha
authors.initials: J
authors.lastname: Hernesniemi
authors.forename: Mika
authors.initials: M
authors.lastname: Niemelä
authors.forename: Timo
authors.initials: T
authors.lastname: Koivisto
authors.forename: Antti
authors.initials: A
authors.lastname: Ronkainen
authors.forename: Jaakko
authors.initials: J
authors.lastname: Rinne
authors.forename: Juha
authors.initials: J
authors.lastname: Jääskeläinen
mesh_terms: D020771:Anterior Cerebral Artery / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D002533:Cerebral Angiography; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D008866:Microsurgery; D019635:Neurosurgical Procedures