Surgical Strategy of Asymptomatic Unruptured Cerebral Aneurysms

To determine the surgical indication of asymptomatic unruptured cerebral aneurysm (AUCA), we reviewed the management of a total of 136 patients with AUCA's (158 aneurysms) that were diagnosed at our hospitals during the past 23 years. Ninety-six patients had incidentally discovered aneurysms and no history of subarachnoid hemorrhage (SAH) (Group A), and 40 patients had a history of SAH from a different aneurysm that had been repaired successfully (Group B). In 103 patients surgically treated (79 in Group A and 24 in Group B), we assessed operative outcome. No patient died and morbidity occurred in 9 patients (8.7%, 8.9% in Group A and 8.3% in Group B, 4.7% in patients with a small AUCA and 29.4% in those with a large AUCA). Statistical analysis revealed that group, patient age and sex, and aneurysmal location had an independent correlation with surgical outcome and that only aneurysmal size approached statistical significance (p=0.004). In 33 surgically untreated patients followed for a median follow-up time of 4.8 years, there were 11 first episodes of hemorrhage from a previously unruptured aneurysm, giving a total rupture incidence of 33.3% (23.5% in Group A and 43.8% in Group B, 28% in patients with a small AUCA and 57% with a large AUCA) and an average annual rupture incidence of 6.9%. The risk of aneurysmal rupture was associated with hypertension. Statistical analysis revealed that the only variable that tended to predict rupture was the size of the aneurysm (p=0.056). There was no difference of rupture incidence between ages from 50's to 70's, except for 80's with no incidence of rupture. We concluded that a small AUCA should be operated on because the risk of rupture exceeded the risk of morbidity, especially in patients of Group B and those with hypertension. If the patient is not over 80 years old, surgery is also indicated for a large AUCA because of its higher rupture rate.