title: Results of re-exploration because of compromised distal blood flow after clipping unruptured intracranial aneurysms.
abstract: BACKGROUND
  One of the major causes for performing unplanned re-exploration of a craniotomy after microsurgery for unruptured intracranial aneurysms (UIAs) is compromised distal blood flow after clipping. Therefore, it is important to identify the causes of compromised distal blood flow after clipping and the factors that influence the prognosis for re-exploration in order to decrease ischemic complications related to clipping UIAs.
  
  
  METHODS
  Between January 2007 and December 2013, 1954 patients underwent microsurgery for UIAs. In this cohort, 20 patients (1.0%) required unplanned re-exploration of the craniotomy for several reasons, and 11 patients (0.6%) underwent unplanned re-exploration with clip repositioning or changing of the previous clip because of compromised distal blood flow after clipping. Patient characteristics, aneurysm properties, intraoperative findings, annual incidence and prognosis were analyzed in these 11 patients.
  
  
  RESULTS
  The annual incidence of re-exploration has gradually decreased since the introduction of several intraoperative monitoring techniques. In total, 3.0% of UIAs in the M1 trunk, 0.8% of UIAs at the origin of the anterior choroidal artery (AchA) and 0.5% of UIAs at the bifurcation of the middle cerebral artery (MCA) required re-exploration. Here, all 11 UIAs had broad necks, and atherosclerosis was identified around 10 UIAs. Six patients with compromised MCA flow demonstrated relatively better outcomes following re-exploration than five patients with a compromised lenticulostriate artery (LSA) or AchA flow. Four patients with delayed ischemic symptoms demonstrated relatively better outcomes than the seven patients who developed ischemic symptoms immediately postoperatively.
  
  
  CONCLUSIONS
  Clinicians need to be more careful not to compromise distal blood flow when clipping UIAs at the MCA and AchA origin. Various intraoperative monitoring techniques can help reduce the incidence of compromised distal blood flow after clipping.
authors.affiliation: Department of Neurosurgery, Asan Medical Center, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul, 138-736 l, South Korea.
authors.forename: Wonhyoung
authors.initials: W
authors.lastname: Park
authors.forename: Jae Sung
authors.initials: JS
authors.lastname: Ahn
authors.forename: Sung Ho
authors.initials: SH
authors.lastname: Lee
authors.forename: Jung Cheol
authors.initials: JC
authors.lastname: Park
authors.forename: Byung Duk
authors.initials: BD
authors.lastname: Kwun
mesh_terms: D000368:Aged; D002545:Brain Ischemia / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D002536:Cerebral Arteries / Q000503:physiopathology / Q000601:surgery*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003399:Craniotomy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000503:physiopathology / Q000601:surgery*; D008297:Male; D008866:Microsurgery / Q000009:adverse effects*; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D012086:Reoperation; D013525:Surgical Instruments