Unruptured intracranial aneurysm and microsurgical exclusion: the need of a randomized study of surgery versus natural history

摘要

Although unruptured intracranial aneurysm (UIA) is becoming a more common finding nowadays, determining the optimal treatment strategy is difficult because the risk of rupture is poorly understood and surgery is not without its own hazards. As the mortality rate after rupture is estimated to range from 56 to 83%, the final therapeutic decision is the result of an analysis of rupture risk and the risks related to surgical exclusion, which may be determined by consideration of the risk factors. We considered the UIA to have a high risk of rupture if it was located on the vertebrobasilar arterial system (RR: 4.4; CI 95%, 2.7-6.8), between 7 and 12 mm in size (RR: 3.3; CI 95%, 1.3-8.2) or larger (RR: 17; CI 95%, 8-36.1), multilobular and had a ratio of depth to width greater than 3.4 (risk x 20). A family history of UIA would constitute a major rupture risk (two to seven times that of spontaneous UIA). Other factors related to UIA rupture include arterial hypertension (RR: 1.46; CI 95%, 1.01-2.11) and smoking (RR: 3.04; CI 95%, 1.21-7.66). After microsurgical exclusion, the morbidity and mortality rates were calculated as 9 and 1.5%, respectively. Microsurgical risk factors were age (32% > 65 years), and factors related to the UIA itself and surgery, such as size (14% > 15 mm), location, presence of atherosclerosis and difficulty of surgical clip application. The incidence of rupture after microsurgical exclusion was estimated to be 0.2% per year, and complete microsurgical exclusion was achieved in 90% of patients. A randomised study of microsurgical exclusion of UIA would offer further proof of our therapeutic hypotheses.