title: Carotid siphon geometry and variants of the circle of Willis in the origin of carotid aneurysms.
abstract: This study evaluated anatomical variants in the carotid siphon and of the circle of Willis in patients with aneurysms. We performed a retrospective analysis of cerebral angiographies. The Control Group was composed of patients without aneurysms. Posterior communicating artery (PcomA) aneurysms were more common in women (p<0.05), and the anterior communicating artery (AcomA) aneurysms in men (p<0.1). The incidence of fetal-type PcomA was higher in cases with co-occurring PcomA aneurysm (24 versus 8%, p<0.05). Patients with AcomA aneurysm had higher incidence of A1 hypoplasia (p<0.0001, OR=32.13, 95%CI 12.95-79.71) and lower frequency of fetal-type PcomA compared to their control counterparts (p=0.0125). The angle of carotid siphon was narrower in patients with PcomA aneurysm (27.3±19.1 versus 34.8±22.6, p=0.028). In conclusion, a narrower carotid siphon or the presence of fetal-type PcomA or A1 hypoplasia may cause hemodynamic stress, thereby promoting the formation of aneurysms in susceptible individuals.
authors.affiliation: Hospital Universitário Onofre Lopes, Natal RN, Brazil. angelo@neuronrn.com.br
authors.forename: Ângelo Raimundo
authors.initials: ÂR
authors.lastname: Silva Neto
authors.forename: Ródio Luis Brandão
authors.initials: RL
authors.lastname: Câmara
authors.forename: Marcelo Moraes
authors.initials: MM
authors.lastname: Valença
mesh_terms: D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging* / Q000473:pathology; D016022:Case-Control Studies; D002533:Cerebral Angiography; D002941:Circle of Willis / Q000000981:diagnostic imaging / Q000473:pathology*; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000000981:diagnostic imaging / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies