Recurrence of an internal carotid artery aneurysm after complete exclusion by a Willis covered stent

Treatment of selective intracranial aneurysms treated with a Willis covered stent is safe and effective. We describe a previously unreported case of a large, irregular, carotid-ophthalmic aneurysm that was treated with a Willis covered stent. An immediate angiogram after the procedure showed complete occlusion of the aneurysm. However, a six-month follow-up angiogram demonstrated contrast media filling of the aneurysm neck. To the best of our knowledge, this is the first report of a recurrent aneurysm treated with a Willis covered stent because of a membrane partially isolated with the stent. This case suggests that an aneurysm that is treated with a Willis covered stent might recanalise, and the risk of aneurysm rupture persists when the membrane of the stent is isolated with the stent. Therefore, follow-up angiography is necessary, even if an immediate angiogram shows complete aneurysm occlusion. Long-term follow-up is required, and the final outcome of such a case is still unknown.