Risk Factors for Intracranial Aneurysm Recanalization After Endovascular Treatment.

Overview

Endovascular treatment is now the first line treatment for the management of intracranial aneurysms. However aneurysm recanalization is an important limitation to this treatment. Several factors seems to be associated with aneurysm recanalization including medical history of the patient, aneurysm status (ruptured or unruptured), aneurysm size and location, modalities of treatment, immediate post-operative occlusion of the aneurysm. A precise knowledge of factors increasing the risk of aneurysm recanalization is quite important to optimize strategy of treatment and reduce the recanalization rate. No large, prospective, multicenter trial dealing with this question has been published in the literature.

The prevalence of intracranial aneurysms is high (between 2 and 3%). The major risk of an intracranial aneurysm is its rupture leading to intracranial bleeding (subarachnoid, parenchymal and/or intraventricular) associated with mortality and morbidity. Endovascular treatment is now the first line treatment for both ruptured and unruptured aneurysms. One major limitation of this treatment is aneurysm recanalization observed in approximately 20% of aneurysms and leading to retreatment in approximately 10% of aneurysms. CARAT trial has shown that the risk of rebleeding after aneurysm coiling is significantly associated with the quality of aneurysm occlusion. The risk of rebleeding is 1.1% in case of complete occlusion, 2.9% when aneurysm occlusion is between 91 and 99%, 5.9% when aneurysm occlusion is between 70 et 90%, and 17.6% when aneurysm occlusion is less than 70%. However it should be outlined that few studies have clearly analyzed the relation between recanalization and rebleeding. Several factors are probably associated with aneurysm recanalization. Ruptured aneurysms are more prone to aneurysm recanalization than unruptured aneurysm. Age, elevated blood pressure, smoking probably play a role in aneurysm recanalization. Anatomical features are also probably key factors for aneurysm recanalization. Aneurysm and neck sizes are probably important factors for aneurysm recanalization. The role of aneurysm location is more controversial. Therapeutic factors certainly play also an important role, but precise analyses are still missing. The quality of post-operative aneurysm occlusion is probably important for the future evolution of the aneurysm. Surface-modified coils have not demonstrated any efficacy to prevent aneurysm recanalization. The role of adjunctive techniques has also not precisely be evaluated (remodeling, stenting).