Carotid siphon geometry and variants of the circle of Willis in the origin of carotid aneurysms

• Main Authors: Ângelo Raimundo Silva Neto, Ródio Luis Brandão Câmara, Marcelo Moraes Valença
• Format: Article
• Language: English
• Published: Academia Brasileira de Neurologia (ABNEURO) 2012-12-01
• Series: Arquivos de Neuro-Psiquiatria
• Subjects: aneurisma cerebral; sifão carotídeo; artéria comunicante fetal; hipoplasia A1; artéria carótida
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0004-282X2012001200003&lng=en&tlng=en

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.