Abstract
Although great progress has been made in the surgical management of cerebral aneurysms, successful treatment of giant thrombosed aneurysms is still difficult. Parent artery occlusion therapy has been accepted as an alternative treatment for these aneurysms. However, several problems have been reported in terms of the occlusion therapy.
We have experienced 13 patients with giant thrombosed aneurysms: 3 at the cavernous portion of the internal carotid artery (ICA), 3 at the middle cerebral artery (MCA), 3 at the vertebral artery (VA), 3 at the basilar artery (BA) and 1 at the superior cerebellar artery (SCA). Nine cases were treated surgically (parent artery occlusion for 3 ICA aneurysms, neck clipping for 2 MCA aneurysms, and aneurysmectomy in 2 aneurysms) and 4 cases conservatively. While postoperative results were fairly good in cases with ICA and MCA aneurysms, aneurysms in the posterior fossa were difficult to manage surgically.
We constructed a hydraulic vascular model for the vertebro-basilar system with a giant aneurysm from silicon and glass tubes with lengths and diameters similar to those of an average adult. When unilateral VA was occluded proximal to the PICA, reversed flow from the other VA to the PICA was observed, which decreased the intraaneurysmal stagnation. Partial occlusion of the proximal VA might be preferable so as to have a residual flow value equal to that of PICA. When unilateral VA was occluded distal to the PICA, stagnation was observed in aneurysms whose neck was more than 7 mm (2.8 tubular diameter) away from the VA union.
Stagnation in the basilar head aneurysm depended on the occlusion site and the tangential flow at the aneurysmal neck. The longest half-time was observed when the BA was occluded distal to the exit of the SCA and the flow was less than 20 ml/min. In cases where the diameters of Pcoms differed greatly, intraaneurysmal thrombosis might be enhanced by placing a bypass to the PCA on the side of the smaller Pcom.
