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

• Published in: Arquivos de neuro-psiquiatria Vol. 70; no. 12; pp. 917 - 921
• Main Authors: Silva Neto, AR, Camara, RLB, Valenca, M M
• Format: Journal Article
• Language: English
• Published: Brazil Academia Brasileira de Neurologia - ABNEURO 01-12-2012; Academia Brasileira de Neurologia (ABNEURO)
• Subjects: aneurisma cerebral; Aneurysm; Angiography; Arteries; artéria carótida; artéria comunicante fetal; Carotid Artery, Internal - diagnostic imaging; Carotid Artery, Internal - pathology; Case-Control Studies; Cerebral Angiography; Circle of Willis - diagnostic imaging; Circle of Willis - pathology; Female; Hemodynamics; hipoplasia A1; Humans; Hypoplasia; Intracranial Aneurysm - diagnostic imaging; Intracranial Aneurysm - etiology; Male; Middle Aged; NEUROSCIENCES; PSYCHIATRY; Retrospective Studies; sifão carotídeo; Stress; hipoplasia A1; intracranial aneurysm; aneurisma cerebral; sifão carotídeo; carotid siphon; artéria comunicante fetal; artéria carótida; A1 hypoplasia; carotid artery; fetal communicating artery
• ISSN: 0004-282X; 1678-4227; 1678-4227; 0004-282X
• DOI: 10.1590/s0004-282x2012001200003

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.