title: [Morphological characteristics of cerebral aneurysm of Willis' circle: a direct anatomical study].
abstract: OBJECTIVE
  To determine the prevalence and morphologic characteristics of unruptured aneurysms of Willis' circle in a sample of mestizo Colombian population.
  
  
  METHODS
  A mixture of resin and mineral red was injected into cerebral arteries by dissection and canalization of common carotids and vertebral arteries of the encephalons of 125 mestizo male cadavers of 16 to 65 years old. The procedure was carried out during the autopsy course at the Legal Medicine Institute, Bucaramanga - Colombia. Then the encephalons were extracted and fixed. After that, the Willis' circles were identified and the presence of aneurysms at this level was determined with magnifying glass.
  
  
  RESULTS
  A total of nine aneurysms were observed in six brains (4.8%). The most frequent location was the supraclinoid segment of the intern carotid artery, with 4 cases (44.4%), three of which were localized in the origin of the anterior choroidal artery. Additionally, three aneurysms were found in the anterior communicating artery (33.3%). From the remaining cases, one (11.1%) was localized in the pre-communicating segment of the anterior cerebral artery, and the other in the bifurcation of the basilar artery. The average size of the aneurysms was 2.49 mm SD 0.37. The affected encephalons presented concomitant variations of the Willis' circle configuration, being predominant the presence of hypoplasic posterior communicanting arteries.
  
  
  CONCLUSIONS
  The aneurysm prevalence in the evaluated sample was similar to the reported in other populations. In this work, the presence of aneurysms on the origin of the anterior chorioid artery, an unusually reported localization, was prominent.
authors.affiliation: Departamento de Ciencias Basicas, Universidad Industrial de Santander, Bucaramanga, Colombia.
authors.forename: Silvia Tatiana
authors.initials: ST
authors.lastname: Quintero-Oliveros
authors.forename: L E
authors.initials: LE
authors.lastname: Ballesteros-Acuña
authors.forename: J O
authors.initials: JO
authors.lastname: Ayala-Pimentel
authors.forename: P L
authors.initials: PL
authors.lastname: Forero-Porras
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002102:Cadaver; D002941:Circle of Willis / Q000473:pathology*; D003105:Colombia / Q000453:epidemiology; D006801:Humans; D002532:Intracranial Aneurysm / Q000453:epidemiology / Q000473:pathology; D008297:Male; D008875:Middle Aged; D055815:Young Adult