Thrombosis of a giant aneurysm after extracranial-intracranial bypass.

A patient presenting with a giant, fusiform middle cerebral artery aneurysm underwent extracranial to intracranial bypass grafting before permanent occlusion of the aneurysm. The patient was to return 4 months later for endovascular treatment. Arteriography obtained before obliteration revealed complete aneurysmal thrombosis. No further treatment was deemed necessary. Factors predisposing to thrombosis are discussed.