Flow diverters (pipeline embolization device, Silk flow diverter, and Surpass flow diverter) have been developed to treat intracranial aneurysms. These endovascular devices are placed within the parent artery rather than the aneurysm sac. They take advantage of altering hemodynamics at the aneurysm/parent vessel interface, resulting in gradual thrombosis of the aneurysm occurring over time. Subsequent inflammatory response, healing, and endothelial growth shrink the aneurysm and reconstruct the parent artery lumen while preserving perforators and side branches in most cases. Flow diverters have already allowed treatment of previously untreatable wide neck and giant aneurysms. There are risks with flow diverters including in-stent thrombosis, perianeurysmal edema, distant and delayed hemorrhages, and perforator occlusions. Comparative efficacy and safety against other therapies are being studied in ongoing trials. Antiplatelet therapy is mandatory with flow diverters, which has highlighted the need for better evidence for monitoring and tailoring antiplatelet therapy. In this paper we review the devices, their uses, associated complications, evidence base, and ongoing studies. 1. Introduction During recent decades, endovascular treatment of cerebrovascular aneurysms has evolved to include unassisted coil embolization techniques, whose efficacy and safety are supported by class-1-evidence, assisted coil embolization techniques, and newly developed techniques using flow diverters [1]. While the various coil embolization techniques, including balloon assisted and stent assisted coiling, are targeted towards the aneurysm sac, flow diverters represent a paradigm shift with the intervention carried out in the parent artery [2, 3]. Flow diverter aneurysm embolization can be combined with coil embolization, further expanding the options available to clinicians and patients [3]. Flow diverters were first tested in untreatable aneurysms or those that had failed previous endovascular therapy [2]. With the approval of these devices in the USA, Europe, and other countries experience with “off-label” uses is evolving. In this paper we review the use of flow diverters for treatment of intracranial cerebral aneurysms. We review the putative mechanism of action, the technical features of devices and their uses, and the evidence for efficacy and safety of flow diverters for intracranial aneurysms. 2. Flow Diversion and Mechanism of Action Flow diverters are stent-like devices that are deployed endovascularly to treat aneurysms. Conceptually, flow diverters allow
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