Abstract
To assess the usefulness of surgery in patients with unruptured cerebral aneurysms to prevent subarachnoid hemorrhage (SAH), we analyzed surgical complications, long-term follow-up results of surgery, and occurrence of SAH in unoperated patients.
In the past 8 years (1992-1999), we found 271 patients with unruptured cerebral aneurysms. Excluding patients who had undergone clipping surgery for the unruptured aneurysms together with ruptured aneurysm at one time, we investigated 105 operated patients and 92 unoperated patients. The mean size of the aneurysm was 7.1 mm for operated patients, and 6.2 mm for the unoperated patients. Among unoperated patients, 6 had a SAH and 5 died. Two other patients died unexpectedly. One patient died due to mass effect of the aneurysm. Patients with aneurysms smaller than 5 mm did not have a SAH. However, the annual rupture rate for patients with aneurysms of 5-15 mm was 9.4%/year.
Surgical results were favorable. There was no mortality for patients with an aneurysm smaller than 5 mm. Surgical morbidity for this group was 2.4%. The operative risk for patients with aneurysms larger than 5 mm was higher. Mortality and morbidity after surgical treatment of patients with aneurysms between 5-15 mm were 1.8% and 5.5%, respectively. Only 1 patient had a SAH after surgery for the unruptured cerebral aneurysm. The operative risk for patients with aneurysms over 15 mm was 37.5%.
These results suggest that surgical treatment is necessary for patients with aneurysms of 5-15 mm. While it may be better to observe patients with aneurysms smaller than 5 mm, further investigation of the natural course of unruptured cerebral aneurysms in relation not only to aneurysm size but also to other factors such as aneurysm shape, hypertension, and history of SAH is necessary. For large aneurysms (<15 mm), careful assessment of the benefits of surgery is needed because of the high operative risk.
