title: Infraoptic anterior cerebral artery: review, report of two cases and an anatomical classification.
abstract: BACKGROUND
  Infraoptic course of the pre-communicating anterior cerebral artery (A1) is a rare anomaly. In total, there are 42 examples reported in the literature. We report two further patients. The first had an intradural cerebral aneurysm at the low bifurcation of an internal carotid artery (ICA) with bilateral infraoptic course of A1. The second had right infraoptic course of A1 with associated left parietal cerebral arteriovenous malformation and is the first report of such an association.
  
  
  CONCLUSIONS
  Overall, 59% of the examples were associated with cerebral aneurysms. Different terminology such as carotid-anterior cerebral artery anastomosis and infraoptic anterior cerebral artery has been used. Having analyzed the reports of infraoptic A1, we found the vascular configurations of the A1 could be better described by classifying them into four types. Such a classification can facilitate analysis of the embryogenesis explanation for this anomaly and the pathogenesis of the associated aneurysms. Besides, such a classification also has some practical implications.
authors.affiliation: Department of Neurosurgery, Tuen Mun Hospital, Tuen Mun, New Territories, Hong Kong. wongsuito@hotmail.com
authors.forename: S T
authors.initials: ST
authors.lastname: Wong
authors.forename: S C
authors.initials: SC
authors.lastname: Yuen
authors.forename: K F
authors.initials: KF
authors.lastname: Fok
authors.forename: K Y
authors.initials: KY
authors.lastname: Yam
authors.forename: D
authors.initials: D
authors.lastname: Fong
mesh_terms: D000328:Adult; D020771:Anterior Cerebral Artery / Q000002:abnormalities* / Q000473:pathology* / Q000601:surgery; D001921:Brain / Q000098:blood supply; D002343:Carotid Artery, Internal / Q000002:abnormalities / Q000473:pathology / Q000601:surgery; D002533:Cerebral Angiography; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D002532:Intracranial Aneurysm / Q000145:classification / Q000209:etiology* / Q000473:pathology*; D002538:Intracranial Arteriovenous Malformations / Q000209:etiology / Q000473:pathology / Q000601:surgery; D008297:Male; D019635:Neurosurgical Procedures / Q000295:instrumentation / Q000379:methods / Q000592:standards; D009900:Optic Nerve / Q000033:anatomy & histology*; D013525:Surgical Instruments; D016896:Treatment Outcome