Simulation study on therapeutic vertebral artery occlusion for VA-PICA giant aneurysm.

We investigated haemodynamic effects of therapeutic vertebral artery (VA) occlusion on giant aneurysms at the bifurcation of the VA-posterior inferior cerebellar artery (PICA). An hydraulic model of the human vertebro-basilar artery was manufactured from glass and silicone tubes. Glass-spheres 2.5 cm in diameter were placed at the bifurcation as model aneurysms with respective distances of 8.5, 7.5, 6.5 and 5.5 mm between the VA union and aneurysmal neck. A 40% glycerol solution was perfused in this system and the half-life of the dye injected into aneurysms was regarded as an index of intra-aneurysmal stagnation. Flow conditions in aneurysms depended on the presence or absence of the effect of contralateral VA flow as well as the PICA flow. The half-life increased significantly after VA occlusion proximal to the PICA when the aneurysmal neck was more than 7.5 mm away from the VA union and PICA flow volume was less than 12 ml min-1. The half-life in aneurysms located within 6.5 mm from the union changed little after VA occlusion regardless of the PICA flow volumes. The haemodynamic simulation study would be helpful in speculating on the efficacy of this treatment.