The Importance of Long Term Follow-up Angiography after Clipping for the Cerebral Aneurysms: Focusing on "de novo" and Enlarged Unruptured Aneurysms.

Based on the conclusion of our previous report, we performed follow-up angiography on the 61 outpatients who had undergone neck clippings for cerebral aneurysms more than 5 years ago. According to the findings of the original angiograms, they were classified into 4 groups: Group 1 consists of 34 cases without abnormal finding. Group 2a consists of 14 cases with small, unruptured aneurysms, that were too small to operate on. Group 2b is 10 cases with residual aneurysmal necks after the previous surgery and Group 3 is 6 cases of SAH with unknown etiology. In 6 out of the 14 cases (44%) from Group 2a, unruptured, untreated small aneurysms had enlarged over an average of 9.8 years. The characteristics of the patients with such aneurysms are: 1) blood pressure under poor control (p The enlargement of the residual aneurysmal neck was only found in Group 2b in 2 incomplete clipping cases. As well, the origin of the SAH remained unknown in all cases of Group 3 over a 15.8-year period (on average) before follow-up. A total of 8 de novo aneurysms were found in 7 cases (3 cases each in Group 1 and 2a and 1 case in Group 2b). The average time before follow-up was 16.2 years. This incidence (11.5%) is considerably higher than the previously assumed rate of around 1 percent. The characteristics of the patients with de novo aneurysms are: 1) 86% female, 2) the average time before confirmation is as long as 16.2 years, 3) all are cases of multiple aneurysms, and 4) 71% have hypertension. There were close similarities between the features of de novo aneurysm and multiple aneurysm cases. These facts lead us to support the hypothesis that de novo aneurysms are one of multiple aneurysms but develop at a different time. As well, patients with aneurysms have the potential to develop into recurring SAH. The best approach to treatment is to do follow-up angiography periodically.