Middle Cerebral Artery Aneurysm: Proximal Middle Cerebral Artery Aneurysm Treated with Telescoping Flow Diverter Implantation and Loose Coiling After Preparatory Implantation of a Braided Stent as a Scaffold

Abstract

A fusiform aneurysm in the M1 segment of the left-hand middle cerebral artery (MCA) had been incidentally discovered in a 50-year-old female. Diagnostic work-up, including a clinical examination, non-contrast-enhanced computed tomography (NCCT), CT angiography (CTA), and diagnostic angiography (DSA), performed at the original hospital also revealed high-grade, proximal stenosis of the internal carotid artery (ICA) on the left-hand side. The patient was then referred to our institution for endovascular occlusion of the aneurysm. The case was discussed in the weekly neurovascular board meeting where it was decided to perform endovascular, extra-aneurysmatic flow diversion. This would include loose coil packing of the aneurysmal sac to promote thrombosis. Our intention was to keep the flow diverter’s distal and proximal ends away from the MCA and ICA bifurcations in order to minimize the risk of thromboembolic complications potentially caused by covering the side branches, namely, the anterior cerebral artery (ACA) in the A1 and MCA in the M2 segment. Since nearly the entire M1 segment was affected by the fusiform dilatation, the distal and proximal landing zones for the flow diverter were rather short. Therefore, we decided to start by implanting a long, braided stent across the fusiform aneurysm, as this is more porous than a flow diverter. This would be followed by a second treatment session in which two flow diverters would be implanted and the aneurysmal sac loosely packed with coils once the initial stent had stabilized and endothelialization had occurred. Both procedures were carried out under general anesthesia with no clinical or technical complications. To enable good access in the first procedure, the stenosis in the ICA was treated beforehand by balloon dilation and implanting a self-expanding stent. The patient was discharged in a neurologically asymptomatic status after each treatment stage. Follow-up angiography performed 3 months after the second session revealed a complete occlusion of the fusiform aneurysm in the clinically unchanged asymptomatic patient, with no evidence of either intimal hyperplasia in the stented segment or that the side vessels had been negatively affected. The main topic of this chapter is the staged approach to the complex treatment of fusiform intracranial aneurysms starting with the implantation of a braided stent to act as scaffolding for hemodynamically active, low-porosity flow diverters.