title: Microneurosurgical management of aneurysms at the A2 segment of anterior cerebral artery (proximal pericallosal artery) and its frontobasal branches.
abstract: BACKGROUND
  Aneurysms originating from the A2 segment of ACA and its frontobasal branches are rare, forming less than 1% of all IAs. There are only few reports on management of A2As. In this article, we review the practical anatomy, preoperative planning, and avoidance of complications in the microsurgical dissection and clipping of A2As.
  
  
  METHODS
  This review, and the whole series on IAs, is mainly based on the personal microneurosurgical experience of the senior author (JH) in two Finnish centers (Helsinki and Kuopio), which serve, without patient selection, the catchment area in Southern and Eastern Finland.
  
  
  RESULTS
  These two 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 35 patients carrying 35 A2As, forming 1% of all patients with IAs, 0.8% of all IAs, and 3% of all ACA aneurysms. Twenty-one (60%) patients presented with ruptured A2As with ICH in 11 (52%) and IVH in 7 (33%). Nineteen patients (54%) had multiple aneurysms.
  
  
  CONCLUSIONS
  A2As are often small, even when ruptured, with relatively wide base, and they are frequently associated with ICHs of IVHs. Our data suggest that A2As rupture at smaller size than IAs in general. The challenge is to select appropriate approach, locate the aneurysm deep inside the interhemispheric fissure, and to clip the neck adequately without obstructing branching arteries at the base. Unruptured A2As 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*; D001921:Brain / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology; D020520:Brain Infarction / Q000209:etiology / Q000517:prevention & control / Q000601:surgery; D002533:Cerebral Angiography; D003399:Craniotomy / Q000379:methods / Q000592:standards; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D018810:Magnetic Resonance Angiography; D008488:Medical Illustration; D019635:Neurosurgical Procedures / Q000295:instrumentation* / Q000379:methods*; D013345:Subarachnoid Hemorrhage / Q000503:physiopathology / Q000517:prevention & control / Q000601:surgery; D013525:Surgical Instruments / Q000592:standards