Onyx in an experimental aneurysm model: histological and angiographic results

Abstract

Object The use of liquid embolic agents for endovascular treatment of cerebral aneurysms is evolving. The authors' aim was to evaluate the use of Onyx HD-500 in an experimental aneurysm model and to obtain histological and angiographic long-term results. Methods Ten aneurysms were created using an elastase model in rabbits. The aneurysms were embolized using Onyx in combination with an inflated balloon. One animal died 1 day after embolization. The animals were divided into 2 different groups. The animals in the first group (4 rabbits) were killed at 3 months and those in the second group (5 rabbits) were killed at 6 months after embolization. A venous control angiogram was obtained, and the aneurysms were examined histologically. Results In both groups control angiograms demonstrated that all aneurysms were completely occluded. There were no signs of recanalization. Migration of Onyx was seen in 4 animals, leading to the death of 1. Histological examination not only proved the aneurysms to be occluded but also demonstrated a thin layer of endothelium at the neck of the aneurysm. The histological result was identical in both groups. Conclusions This is the first study reporting the formation of a neointima over the neck of aneurysms embolized with Onyx in a rabbit model. Although the technique is challenging and migration of the liquid embolic agent cannot always be prevented, Onyx has a great potential to achieve a durable occlusion of aneurysms.