Rupture of previously unruptured giant carotid aneurysm after superficial temporal-middle cerebral artery bypass and internal carotid occlusion.

A 51-year-old woman with an unruptured giant aneurysm of the internal carotid artery was treated by gradual occlusion of the internal carotid artery in the neck combined with a superficial temporal artery to middle cerebral artery bypass graft. Visual field defects improved after the operation, and thrombosis of the aneurysm was confirmed by angiography and computed tomography. Nevertheless, a fatal hemorrhage occurred 34 days after the final turn of the Selverstone clamp. The possible mechanism of rupture of the apparently thrombosed aneurysm is discussed. There is a risk of rupture of the aneurysm as long as the aneurysmal lumen remains after proximal ligation, no matter how small it may be.