Severe in-stent stenosis after intracranial saccular aneurysm treatment with a flow diverter stent

Background: The development of flow diverters (FDs) has provided neurointerventionalists with an additional option for the treatment of intracranial aneurysms. These devices lead to aneurysm occlusion by triggering intraaneurysmal thrombosis through their potential to disrupt blood flow into the aneurysm sac and by inducing intimal hyperplasia. This enables the complete exclusion of the aneurysm from circulation, but it is also responsible for in-stent stenosis. Case description: A 68-year-old latin woman with a medical history of irregular treated arterial hypertension and a 40 year history of smoking habit was diagnosed with an unruptured intracranial saccular aneurysm in the left internal carotid artery and then referred to be treated with a Flow Diverter stent. At the 6 mont follow-up angiography, a severe in-stent stenosis (>75%) was observed at the distal portion of the stent. The patient was otherwise asymptomatic and no distal flow limitation was observed. It was decided to maintain the dual antiplatelet regimen and a 12 month follow-up angiography was performed, being noticed substantial improvement, with a mild intra-stent stenosis of approximately 25% at the same site. Conclusion: Severe in-stent stenosis in an uncommon finding after aneurysmal treatment with flow diverter devices, but usually with later asymptomatic improvement without any other intervention, being of great importance its knowledge by neurointerventionalists.