Unruptured intracranial aneurysms treated by three-dimensional coil embolization: evaluation of the postoperative aneurysm occlusion volume.

Our purpose was to evaluate the postoperative aneurysm occlusion volume and clinical results of treating unruptured intracranial aneurysm using three-dimensional (3D) coils. Over a 2-year period 62 aneurysms (39 with a neck < or =4 mm, 23 with a neck >4 mm) in 62 patients in five participating centres were treated. The procedure consisted, firstly, of framing the aneurysm with one or more spherical 3D coils, and secondly, of filling it with two-dimensional (2D) helical coils. Anatomical and clinical results were evaluated by univariate analysis. Multivariate analysis was used to identify independent predictors of these results. For neck sizes < or =4 and >4 mm, angiographic occlusion was complete in 31 (79%) and 16 (70%) aneurysms, respectively; the mean percentage of occlusion volume was 31.4% and 29.5%, respectively, and postoperative morbidity was 3% and 4%, respectively, with no significant differences between the two groups. There were no deaths. However, occlusion volume correlated with sac size (P = 0.037) and sac-to-neck ratio <1.5 (P = 0.073), except when three or more 3D coils per aneurysm were used (P = 0.516 and P = 0.308, respectively). Occlusion volume correlated with the number of 3D coils per aneurysm (P < 0.001) and was an independent predictor of angiographic complete occlusion (P = 0.002). The use of the largest number of 3D coils per aneurysm was safe and may improve the postoperative volume and angiographic occlusion of aneurysms with a neck >4 mm, provided the sac-to-neck ratio is > or =1.5.