Flow Diversion Is Not Yet the Complete Package

Abstract

arsaut et al. prepared an article on their results after flow diversion in giant curved and bifurcation experiD ments with very low porosity flow diversion devices. This was done to improve on their prior experience to occlude aneurysms with flow diverters as a stand-alone therapy by progressively increasing the metal density of devices (1). They demonstrated that increasing the metal content of flow diversion devices (from 48 to 64 wire devices and then to double overlapping 64 wire devices) remained insufficient to reliably cause giant end wall bifurcation and curved sidewall aneurysm occlusion. Angiography at 3 months in most cases showed widely patent aneurysms and microscopic photography consistently revealed apertures through the neointima covering the devices, permitting blood flow to keep aneurysms, and branches, patent. As they point out, fundamental problems with devices deployed in a curved configuration include the incident angle of flow and the increased porosity found at the device convexity (2). They did note that the models they constructed were more challenging than previous animal models used as aneurysms were larger, and necks wider. This is an interesting article and many researchers would have argued, as Darsaut et al. did, that low porosity devices would occlude the aneurysm. The classic surgical treatment for giant aneurysms has been either microsurgical direct clip-reconstruction or occlusion followed by a cerebral bypass for those patients who fail in a balloon test occlusion. Nevertheless, the emergence of new endovascular techniques, especially flowdiverting devices, has promised to revolutionize the treatment of giant aneurysms, possibly avoiding major microsurgical operations. However, this article highlights the fact that endovascular therapy is not yet the standard for the treatment of all giant intracranial aneurysms, even in the controlled situation such as