Flow diverters (FDs) have been developed for intracranial aneurysms difficult to treat with conventional endovascular therapy and surgical clipping. We reviewed 94 patients with 100 large or giant unruptured internal carotid artery (ICA) aneurysms treated with Pipeline embolization device (PED) embolization from December 2012 to June 2017 at Juntendo University Hospital. The patients’ mean age was 63.4 years (range, 19–88), and there were 90 women 89.4%. Aneurysm locations were: C4 (45), C3 (4), and C2 (51) in ICA segments. Mean aneurysm size and neck width were 16.9 ± 6.8 mm and 8.3 ± 4.4 mm, respectively, in 40 symptomatic and 60 asymptomatic aneurysms. Follow-up catheter angiographies of 85 patients with 90 aneurysms showed no filling in 62 aneurysms (68.9%), entry remnant in 16 (17.8%), subtotal filling in 11 (12.2), and total filling in 1 (1.1%) with a mean follow-up of 10.2 ± 5.6 months. In-stent stenosis occurred in 1 patient and parent artery occlusion in 2 during follow-up. Hemorrhagic complications occurred in 4 (4.3%): delayed aneurysm rupture (2) and intraparenchymal hemorrhage (2). Ischemic complications with neurological symptoms occurred in 2 (2.1%): very delayed device occlusion (1) and intraprocedural distal embolism (1). Eighteen patients (45%) showed improvement in pre-existing cranial nerve dysfunction because of the aneurysm’s mass effect, 3 patients (7.5%) worsened. One patient died of systemic organ failure unassociated with the procedure. Morbidity and mortality rates were 4.3% and 1.1%, respectively. PED embolization for unruptured large and giant ICA aneurysms is safe and efficacious. Physicians should be observant of characteristic risks associated with FD therapy.

Flow diversion stents (FDSs) are constructed from high-density braided mesh, which alters intra-aneurysmal hemodynamics and leads to aneurysm occlusion by inducing thrombus formation. Although there are potential complications associated with FDS embolization, one of the serious complications is the parent artery occlusion due to the in-stent thrombosis. A 72-year-old woman with a symptomatic giant fusiform aneurysm in the cavernous segment of ICA underwent single-layer pipeline embolization device (PED) embolization. Six-month and 1-year follow-up conventional angiographies showed the residual blood flow in the aneurysm. Two-year follow-up MRI showed the aneurysm sac shrinkage and the antiplatelet therapy was discontinued. The patient suffered from symptomatic parent artery occlusion due to the in-stent thrombosis, 4 months after antiplatelet therapy discontinuation. The patient with the incompletely occluded aneurysm after PED embolization should be given long-term antiplatelet therapy because of the risk of delayed parent artery occlusion.

Background Flow diversion with the Pipeline embolization device (PED) is a widely accepted treatment modality for aneurysm occlusion. Previous reports have shown no recanalization of aneurysms on long-term follow-up once total occlusion has been achieved. Case description We report on a 63-year-old male who had a large internal carotid artery cavernous segment aneurysm. Treatment with PED resulted in complete occlusion of the aneurysm. However, follow-up angiography at four years revealed recurrence of the aneurysm due to disconnection of the two PEDs placed in telescoping fashion. Conclusion Herein, we present the clinico-radiological features and discuss the possible mechanisms resulting in the recanalization of aneurysms treated with flow diversion.

A delayed aneurysm rupture after flow diverter therapy is a rare but serious complication. Due to the anatomical specificity, a delayed rupture of a carotid cavernous aneurysm may cause a direct carotid cavernous fistula (dCCF). We present a novel therapeutic approach for treatment of dCCF after flow diverter therapy using the Pipeline embolization device (PED). An 86-year-old woman suffered from dCCF after PED embolization. A microcatheter was advanced through the transvenous approach into the cavernous sinus (CS) and further inserted into the aneurysm sac via the rupture point. Coil embolization of both the aneurysm sac and a small part of the CS adjacent to the fistulous site could achieve not only the immediate aneurysm occlusion but also the rupture point obliteration with a small amount of coil mass in the CS.

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Lateral wall paraclinoid aneurysms (LPA) are a rare type of aneurysm located on the lesser curve side of the internal carotid artery (ICA) bend, at the level of the anterior clinoid process. The objective of this study was to assess the influence of flexion of the ICA on the morphology of aneurysms and outcome of endovascular treatment. Between 2003 and 2018, we treated 643 cases of unruptured paraclinoid aneurysms with endovascular therapy in our institution. Of those cases, aneurysms projecting laterally on preoperative angiography were defined as LPA. The degree of bending of the ICA (ICA angle) was measured and statistically analyzed in relation to the aneurysm characteristics and the occlusion status after treatment. In all, 43 aneurysms were identified. ICA angle was positively correlated with the maximum dome size of the aneurysm ( P <0.01) and the aspect ratio ( P <0.01), and negatively correlated with the volume coil embolization ratio ( P <0.01). Complete occlusion (CO) was achieved in 23 cases (53.5%) immediately after treatment, and in 35 cases (81.4%) at follow-up. The mean ICA angle in the incomplete occlusion group was significantly larger than in the CO group ( P = 0.01). Larger ICA angle resulted in recurrence, whereas smaller ICA angle was more likely to obtain progressive thrombosis ( P = 0.02). Endovascular treatment for LPA was safe and effective. The degree of flexion of the ICA may contribute to the level of hemodynamic stress on the aneurysm, its morphology, and the embolization effect.

We report two cases of proximal posterior cerebral artery (PCA) aneurysms treated with endovascular parent artery occlusion (PAO) with coils. In both cases, selective injection from the 4 F distal access catheter clearly showed the perforating arteries arising from the PCA. Case No 1, a 49-year-old woman, was successfully treated with preservation of a paramedian artery. Case No 2, a 54-year-old woman, was treated in the same manner. The patient underwent extensive thalamic infarction after the procedure because of paramedian artery occlusion. Endovascular PAO with coils is feasible for proximal PCA aneurysms; however, preservation of perforating arteries arising from the PCA is mandatory.

The management of giant vertebrobasilar junction (VBJ) aneurysms is extremely challenging. Flow diverter (FD) therapy has become an important alternative to treat difficult intracranial aneurysms for both open surgery and conventional endovascular therapy. Herein, we report a rare case of a giant fusiform VBJ aneurysm in a child that is successfully treated with FD therapy.