Spontaneous Thrombosis of an Unruptured Internal Carotid Artery Aneurysm: A Case Report

Spontaneous thrombosis of unruptured aneurysm is relatively rare. In previous reported cases, aneurysms thrombosed after some intervention for associated vascular lesions such as AVM, moyamoya or aneurysm. There have been no reports on spontaneous thrombosis of a usual unruptured aneurysm of anterior circulation without any intervention. A 70-year-old female patient visited our hospital for further evaluation of an unruptured aneurysm. One year before visiting our hospital, she was examined by MRI and MRA at another hospital. MRA disclosed an aneurysm at the right internal carotid artery. MRI and MRA at our hospital showed the aneurysm was the same as in the previous examination. The unchanged size and shape of the aneurysm on MRA over the course of a year may mean the aneurysm was not a dissecting aneurysm. Eight months after the initial study at our hospital, 3D-CTA failed to show the aneurysm. The aneurysm was thought to thrombose from the MRI findings. The exact mechanism of spontaneous thrombosis of the aneurysm is obscure.