[Case of an internal carotid artery aneurysm complicated with coil protrusion during embolization].

Coil migration during cerebral aneurysm embolization is rare, but one of the most troublesome events. A 65-year-old woman was referred to our hospital for the treatment of a cerebral aneurysm. Angiography showed the aneurysm at the C3 portion of the right internal carotid artery. The neck of the aneurysm was wide. A detachable coil was placed into the aneurysm using the balloon neck plasty technique and was detached after confirmation of its stability. However, after detachment, the coil started to migrate. The balloon was inflated to prevent coil migration and another coil was inserted into the aneurysm to stabilize the migrated coil. Finally, the aneurysm was subtotally embolized with 9 coils. The postoperative course was uneventful. Coil migration may occur especially in a wide-neck aneurysm. Appropriate coil selection is important to prevent such migration. Subsequent coil insertion, retrieval of the migrated coil, and stent placement are the treatment options for coil migration.