title: Risk factors and consequences of unexpected trapping for ruptured anterior communicating artery aneurysms.
abstract: BACKGROUND
  While clipping cerebral aneurysms at the neck is optimal, in some cases this is not possible and other strategies are necessary. The purpose of this study was to describe the incidence, risk factors, and outcomes for inability to clip reconstruct ruptured anterior communicating artery (ACoA) aneurysms.
  
  
  METHODS
  Of the 70 cases of ruptured ACoA aneurysms between January 2006 and December 2013, our institutional experience revealed four cases of small ACoA aneurysms that had been considered clippable prior to operation but required trapping. When a unilateral A2 segment of anterior cerebral artery (ACA) was compromised by trapping, revascularization was performed by bypass surgery. Clinical presentation, angiographic characteristics, operative approach, intraoperative findings, and treatment outcomes were assessed.
  
  
  RESULTS
  Very small aneurysm under 3 mm was a risk factor for unexpected trapping. The reason for unexpected trapping was laceration of the aneurysmal neck in two cases, and lack of clippaple component due to disintegration of entire aneurysmal wall at the time of rupture in the others. Aneurysms with bilateral A1 were treated with sole trapping through pterional approach in two cases. The other two cases had hypoplastic unilateral A1 segment of ACA and were treated with combination of aneurysm trapping and revascularization of A2 segment of ACA through interhemispheric approach. No patients had new cerebral infarctions of cortical ACA territory from surgery. Cognitive dysfunction was observed in three cases, but all patients became independent at 12-month follow up.
  
  
  CONCLUSIONS
  Unexpected trapping was performed when ruptured ACoA aneurysms were unclippable. Trapping with or without bypass can result in reasonable outcomes, with acceptable risk of cognitive dysfunction.
authors.affiliation: Department of Neurosurgery, Kurashiki Central Hospital, Kurashiki, Okayama, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Fukuda
authors.affiliation: Department of Neurosurgery, Himeji Medical Center, Himeji, Hyogo, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Iwasaki
authors.affiliation: Department of Neurosurgery, Shiroyama Hospital, Habikino, Osaka, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Murao
authors.affiliation: Department of Neurosurgery, Kurashiki Central Hospital, Kurashiki, Okayama, Japan.
authors.forename: Sen
authors.initials: S
authors.lastname: Yamagata
authors.affiliation: Division of Neurosurgery, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: Benjamin W Y
authors.initials: BW
authors.lastname: Lo
authors.affiliation: Division of Neurosurgery, St. Michael's Hospital, Toronto, Ontario, Canada.
authors.forename: R Loch
authors.initials: RL
authors.lastname: Macdonald
keywords: Anterior communicating artery aneurysm; cerebral revascularization; cognitive function; subarachnoid hemorrhage; unexpected trapping
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