title: The critical role of the external carotid artery in cerebral perfusion of patients with total occlusion of the internal carotid artery.
abstract: OBJECTIVE
  The ipsilateral external carotid artery (ECA) can potentially provide an important collateral pathway for cerebral blood flow in the presence of occlusion or severe stenosis of the internal carotid artery (ICA), recovering up to 15% of the middle cerebral arterial flow. The aim of the study is to elucidate the role of ECA in cerebral flow of patients with total ICA occlusion.
  
  
  METHODS
  Retrospective study of prospectively collected data of 139 patients with total ICA occlusions. The patients were divided to symptomatic and asymptomatic and were categorized in four subgroups according to the stenosis rates: A) ipsilateral ECA<70% and contralateral internal carotid artery stenosis <70%; B) ipsilateral ECA stenosis <70% and contralateral internal carotid artery stenosis ≥70%; C) ipsilateral ECA stenosis ≥70% and contralateral ICA stenosis <70%; D) ipsilateral ECA stenosis ≥70% and contralateral ICA stenosis ≥75%.
  
  
  RESULTS
  Fifty eight (41.7%) patients were asymptomatic. The highest rate (48.2%) of asymptomatic patients was in Group A. Among patients with strokes, the highest rate belonged in groups C and D (44.4% and 50% respectively) where ipsilateral ECA stenosis was ≥70% irrespectively of the contralateral ICA patency. Ipsilateral external carotid artery stenosis ≥70% proved to be and independent risk factor for symptom presentation (P=0.013).
  
  
  CONCLUSIONS
  The study reveals the significant role of ECA patency in cerebral flow in patients with ICA occlusion.
authors.affiliation: Department of Vascular Surgery, Attikon University, Hospital, University of Athens, Athens, Greece. dalainas@freemail.gr
authors.forename: I
authors.initials: I
authors.lastname: Dalainas
authors.forename: E D
authors.initials: ED
authors.lastname: Avgerinos
authors.forename: M E
authors.initials: ME
authors.lastname: Daskalopoulos
authors.forename: A
authors.initials: A
authors.lastname: Papapetrou
authors.forename: C P
authors.initials: CP
authors.lastname: Papasideris
authors.forename: V
authors.initials: V
authors.lastname: Katsikas
authors.forename: K
authors.initials: K
authors.lastname: Xiromeritis
authors.forename: K
authors.initials: K
authors.lastname: Moulakakis
authors.forename: T
authors.initials: T
authors.lastname: Gianakopoulos
authors.forename: C D
authors.initials: CD
authors.lastname: Liapis
mesh_terms: D015901:Angiography, Digital Subtraction; D058070:Asymptomatic Diseases; D002342:Carotid Artery, External / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016893:Carotid Stenosis / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation; D016009:Chi-Square Distribution; D003097:Collateral Circulation; D005260:Female; D006115:Greece; D006801:Humans; D002546:Ischemic Attack, Transient / Q000209:etiology / Q000503:physiopathology; D016015:Logistic Models; D018810:Magnetic Resonance Angiography; D008297:Male; D020768:Middle Cerebral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015999:Multivariate Analysis; D011237:Predictive Value of Tests; D011379:Prognosis; D012039:Regional Blood Flow; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D020521:Stroke / Q000209:etiology / Q000503:physiopathology; D014057:Tomography, X-Ray Computed; D018616:Ultrasonography, Doppler, Duplex