Asymptomatic aneurysms. Literature meta-analysis and indications for treatment

Autopsy and angiographic studies indicate that cerebral aneurysms occur in an estimated 0.2% to 8.9% of the general population. Modern noninvasive imaging techniques now detect these lesions in ever increasing numbers, and neurosurgeons are faced with a difficult decision about whether to recommend surgical treatment of incidentally discovered asymptomatic unruptured aneurysms (AA). While in the past an expectant management was generally recommended for AA, elective surgery is now advocated because of the risk of bleeding of the untreated aneurysm and the low operative morbidity and mortality rates of modern microneurosurgery. We performed a meta-analysis of the literature on morbidity and mortality from elective surgery for AA to obtain a more generalizable estimate of operative risk than is currently available. Our meta-analysis contained 19 series consisting of 343 cases of elective surgery for AA. There was a total of 3 deaths for a combined mortality rate of 0.87%, and a total of 15 deficits for a combined morbidity rate of 4.3%. These results compare favorably with the 10.3% natural history cumulative risk of mortality for unruptured aneurysms. The authors' personal experience with AA management was also reviewed and a particularly significant illustrative case is briefly reported. We recommend treatment for all asymptomatic aneurysms incidentally discovered particularly if: a) the aneurysm size is greater than 5 mm and arterial hypertension is present; b) the patient is otherwise healthy; c) the estimated life expectancy is > or = 10 years.