DENOVO ANEURYSM FORMATION AND ANEURYSM GROWTH FOLLOWING THERAPEUTIC CAROTID OCCLUSION FOR INTRACRANIAL INTERNAL CAROTID-ARTERY (ICA) ANEURYSMS

We herein report the long term results of 27 intracranial internal carotid artery (ICA) aneurysms treated by indirect surgery such as a trapping of the aneurysm or carotid ligation either with or without EC--IC bypass. These patients were then followed for a mean period of 10 years. Seventy-four percent of the aneurysms were categorized as either being giant or large. Late complications were observed in 7 patients. A rupture of newly formed aneurysms at the anterior communicating artery occurred in 2 cases 8 or 9 years after either trapping or performing a ICA ligation, respectively. In these patients, previous angiography could not reveal any abnormalities at the anterior communicating artery. A rupture of a contralateral ICA aneurysm was seen in a patient whose ipsilateral ICA was ligated for a ICA aneurysm 22 years previously. An enlargement of the contralateral giant cavernous ICA aneurysm became symptomatic 6 years after a partial ligation of the ICA combined with an EC-IC bypass for a giant cavernous carotid artery aneurysm on the other side. Two cases of sudden death occurred in a young patient and an elderly patient with a small anterior communicating artery aneurysm, 9 and 19 years respectively, after trapping of the ICA aneurysms, although the cause could not be definitely ascertained. Rebleeding occurred in one patient who died 8 years after a carotid ligation and a partial clipping of the ICA aneurysm. Haemodynamic stress may therefore play a major role in inducing new aneurysms or growing aneurysms. Careful consideration should thus be taken whenever a therapeutic carotid occlusion is selected as the treatment for carotid artery aneurysms, and a long term follow-up should be done with MR, angiography or DSA.