FOLLOW-UP-STUDY OF UNRUPTURED ANEURYSMS ARISING FROM THE C3-SEGMENT AND C4-SEGMENT OF THE INTERNAL CAROTID-ARTERY

A follow-up study of unruptured aneurysms arising from the C3 and C4 segments of the internal carotid artery was performed. During the 10-year period from 1979 to 1989, there were 22 patients with 24 aneurysms arising from the C3 or C4 segment of the internal carotid artery. All 24 aneurysms were unruptured. They represented 3% of all intracranial aneurysms and 11% of all internal carotid artery aneurysms diagnosed at the hospital during the 10-year period. Eighteen patients were women and 4 were men. Their ages ranged from 34 to 82 years (mean 63.3 years). Of the 22 patients, 12 (55%) had multiple aneurysms. A follow-up study without treatment was made in 15 of the 22 patients who had a total of 16 unruptured aneurysms arising from the C3 or C4 segment of the internal carotid artery. This study excluded 7 of the 22 patients with a total of eight aneurysms because of operation or death soon after diagnosis. The average maximal dimension of the 16 aneurysms was 5 mm, with a range of 2-17 mm. Follow-up periods varied from 11 months to 10.5 years, with an average of 4.7 years. During this period, none of the 16 aneurysms ruptured, and they remained asymptomatic, except for one aneurysm that had been discovered as a result of the cavernous sinus syndrome. Some surgeons are now attempting direct operations on intracavernous carotid artery aneurysms, even if the aneurysms are unruptured and relatively small. However, this study demonstrates that the risk of rupture of the small unruptured aneurysms arising from the C3 or C4 segment of the internal carotid artery seems to be very small. Further work is necessary regarding the natural history for such aneurysms.