title: Differentiating Carotid Terminus Occlusions into Two Distinct Populations Based on Willisian Collateral Status.
abstract: OBJECTIVE
  The outcomes of acute internal carotid artery (ICA) terminus occlusions are poor. We classified ICA terminus occlusions into 2 groups according to the occlusion pattern of the circle of Willis and hypothesized that clinical outcomes would significantly differ between them.
  
  
  METHODS
  Consecutive patients with acute ICA terminus occlusions evaluated by baseline computed tomographic angiography were enrolled. We investigated the occlusion patterns in the circle of Willis, retrospectively classified patients into simple ICA terminus occlusion (STO; with good Willisian collaterals from neighboring cerebral circulation) and complex ICA terminus occlusion (CTO; with one or more of A2 anterior cerebral artery, fetal posterior cerebral artery occlusion, or hypoplastic/absent contralateral A1; or with poor collaterals from anterior communicating artery) groups, and compared their baseline characteristics and outcomes.
  
  
  RESULTS
  The STO group (n=58) showed smaller infarct volumes at 72 hours than the CTO group (n=34) (median, 81 mL [interquartile range, 38-192] vs. 414 mL [193-540], P<0.001) and more favorable outcomes (3-month modified Rankin Scale 0-3, 44.8% vs. 8.8%, P<0.001; 3-month mortality, 24.1% vs. 67.6%, P<0.001). In multivariable analyses, STO remained an independent predictor for favorable outcomes (odds ratio 6.1, P=0.010).
  
  
  CONCLUSIONS
  Favorable outcomes in STO group suggested that the outcomes of acute ICA terminus occlusions depend on Willisian collateral status. Documenting the subtypes on computed tomographic angiography would help predict patient outcome.
authors.affiliation: Department of Neurology, Ajou University School of Medicine, Ajou University Medical Center, Suwon, Korea.
authors.forename: Sun-Uk
authors.initials: SU
authors.lastname: Lee
authors.affiliation: Department of Neurology, Ajou University School of Medicine, Ajou University Medical Center, Suwon, Korea.
authors.forename: Ji Man
authors.initials: JM
authors.lastname: Hong
authors.affiliation: Department of Radiology, Ajou University School of Medicine, Ajou University Medical Center, Suwon, Korea.
authors.forename: Sun Yong
authors.initials: SY
authors.lastname: Kim
authors.affiliation: Department of Neurology, Samsung Medical Center, Sungkyunkwan University, Seoul, Korea.
authors.forename: Oh Young
authors.initials: OY
authors.lastname: Bang
authors.affiliation: Calgary Stroke Program, Departments of Clinical Neurosciences and Radiology, Hotchkiss Brain Institute, University of Calgary, Calgary, AB, Canada.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Demchuk
authors.affiliation: Department of Neurology, Ajou University School of Medicine, Ajou University Medical Center, Suwon, Korea.
authors.forename: Jin Soo
authors.initials: JS
authors.lastname: Lee
keywords: Carotid artery thrombosis; Cerebral infarction; Circle of Willis; Collateral circulation; Endovascular procedures