Delayed visual deficits and monocular blindness after endovascular treatment of large and giant paraophthalmic aneurysms

Objective: Paraophthalmic aneurysms may exert mass effect on the optic apparatus. Although surgical clipping and endovascular coiling of these aneurysms can be complicated by immediate postoperative visual deterioration, endovascular coil embolization has the unique risk of visual complications later (>24 h) in the perioperative period. Methods: Six patients with a delayed onset of vision loss after technically successful coil embolization of paraophthalmic region aneurysms were identified. All available clinical, angiographic, and cross sectional imaging for these patients, in addition to histopathological data, were reviewed. Results: Six patients who underwent endovascular treatment of paraclinoid aneurysms at our institutions developed delayed postoperative visual decline. Four were treated with combination hydrogel-coated and bare platinum coils, one with hydrogel-coated coils, and one with bare platinum coils. Three patients presented with some degree of visual impairment caused by their aneurysms. Catheter angiography performed after the visual decline revealed no etiology in any of the cases. Magnetic resonance imaging was performed in all patients and was unremarkable in two. At follow-up, two had improved, three remained unchanged, and one patient died before any follow-up assessment of her vision. Conclusion: Both acute and delayed visual disturbances can present after the endovascular treatment of carotid artery paraophthalmic aneurysms. Delayed visual deterioration can be observed up to 35 days after embolization. Although the cause is still undefined, it is likely that the more delayed visual deterioration can be attributed to progression of mass effect and/or perianeurysmal inflammatory change. Our case series raises the possibility that this phenomenon may be more likely with HydroCoil (HydroCoil Embolic System; MicroVention, Aliso Viejo, CA). This possibility should be taken into account by neurointerventionists when selecting a coil type to treat large paraophthalmic aneurysms.