title: Bilateral segmental absence of the internal carotid artery with rete compensation associated with absence of basilar artery: case report.
abstract: BACKGROUND
  Bilateral ICA absence is a rare lesion. Collateral circulation to the middle and anterior cerebral arteries in the absence of one or both ICAs may develop transcranial anastomoses from the external carotid system, a so-called CRM. Very rarely, theses arterial channels are observed in humans.
  
  
  METHODS
  In the following case study, a 38-year-old man presented himself. He had a headache and scalp laceration after having had an accident. A right external carotid angiography identified anastomoses to distal intracranial vessel through the internal maxillary artery, but the intracranial vessels were only faintly visible. A right ascending pharyngeal arteriography showed an abnormal course and anastomoses with the intracranial vessel. The right ICA was absent. The left external carotid angiography demonstrated a network of tortous arteries in the region of the cavernous and petrous portion of ICA. The plexus of vessels on the left side communicated with the proximal part of the cavernous segment of the ICA. Both vertebral angiographies demonstrated a sudden diminution in caliber at the level of vertebrobasilar junction. There was an anomalous arterial collateral circulation originating from vertebral muscular and meningeal branch. There was also an absence of the basilar artery (BA).
  
  
  CONCLUSIONS
  This is the first case with CRM associated with bilateral segmental ICA and BA absence. The cause of this bilateral segmental ICA and BA absence may be maldevelopment of vessel connective tissue or extracellular matrix.
authors.affiliation: Department of Neurosurgery, Seoul Paik Hospital, Inje University College of Medicine, Seoul 100-032, South Korea. hanibalkms@hanmail.net
authors.forename: Myoung Soo
authors.initials: MS
authors.lastname: Kim
authors.forename: Seung-Joon
authors.initials: SJ
authors.lastname: Lee
authors.forename: Chae Heuck
authors.initials: CH
authors.lastname: Lee
authors.forename: Hyo Il
authors.initials: HI
authors.lastname: Park
mesh_terms: D001163:Arteriovenous Anastomosis / Q000502:physiology*; D001488:Basilar Artery / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D001921:Brain / Q000098:blood supply; D002343:Carotid Artery, Internal / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D002533:Cerebral Angiography; D002560:Cerebrovascular Circulation / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology*; D006261:Headache / Q000209:etiology; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000000981:diagnostic imaging*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged