Internal carotid bifurcation aneurysms: frequency, angiographic anatomy and results of coiling in 50 aneurysms

Abstract

Internal carotid artery (ICA) bifurcation aneurysms are uncommon. Little is known about incidence, anatomical characteristics and results of endovascular treatment. We report our experience with endovascular treatment of 50 ICA bifurcation aneurysms in 46 patients. There were 13 men (28%) and 33 women (72%) with a mean age of 49.3 years (range 23-76 years). Of 50 aneurysms, 26 (52%) were ruptured and 24 (48%) were unruptured. Of the 46 patients, 23 (50%) had one to five additional aneurysms. The frequency of ICA bifurcation aneurysms was 2.4% (53 of 2,249, 95% CI 1.8-3.1%). Their mean size was 9.6 mm (median 6 mm, range 2-55 mm). Aneurysm neck was symmetrically on A1 and M1 in 30 aneurysms (60%), dominant on A1 in 14 (28%), on M1 in 2 (4%) and on the ICA in 4 (8%). Aneurysm fundus projection was superior in 28 aneurysms (56%), posterior in 9 (18%), anterior in 10 (20%) and lateral in 3 (6%). Four aneurysms were coiled with balloon assistance. Procedural morbidity and mortality of coiling was 2% each. During follow-up, 7 of 50 aneurysms (all 10 mm or larger) were additionally treated (retreatment rate 14%). ICA bifurcation aneurysms are rare with a frequency of 2.4% of treated aneurysms in our institution. They are often associated with additional aneurysms. Most aneurysm necks are located symmetrically on A1 and M1 and fundus projection is mostly superior. Coiling is safe and effective for the management of these aneurysms. The aneurysms that needed retreatment were >/=10 mm.