Asymptomatic occlusion of the internal carotid artery at the skull base

Three cases are presented of asymptomatic occlusion of the internal carotid artery at level of the skull base due to external compression. In 2 patients the compression was caused by a meningioma infiltrating the skull-base whereas in the third case a giant aneurysm of the i.c.a. caused the compression in the cavernous sinus. Although the patients suffered from eye-movement palsies caused by local compression of the tumour itself it is quite remarkable that this total occlusion of the internal carotid artery was tolerated without neurological deficit at all. It can be concluded that in these patients the collateral circulation through the arterial circle of Willis and the watershed area supplied enough flow to compensate the main arterial occlusion.