Hello thanks for posting here. A previously placed coil in a cerebral artery to migrate into the carotid artery is very rare and unusual, because it has to go against the floors. Coil migration itself is rare and if it migrated, it does into distal arteries. So suggest we have to first confirm whether it is really the coil which is causing the obstruction. A MRA of the brain and neck arteries should be done to get sufficient information. If a coil migration is detected it can be removed by endovascular procedure through an approach from the leg artery (femoral artery) with the help of a snare. The area must be stented after the removal of the coil. If its not possible to remove the coil via endovascular techniques, an open vascular surgery should be done, and coil can be removed and a great repair can be done. So in short it requires investigation and interventional management. In the meantime you should be on blood thinner medications and statins. Wishing you good health. Regards