Complication of the surgical treatment for unruptured cerebral aneurysms is not ignorable especially for high-risk patients whose preoperative score is more than 2. The preoperative score consisted of aneurysm size (0: below 14 mm, 1: 15-24 mm, 2: over 25 mm), location (0: other location than posterior fossa and paraclinoid, 1: paraclinoid, 2: posterior fossa), multiplicity (0: treatable with single approach, 1: different approach necessary), and systemic diseases (0: no disease other than cerebral aneurysm, 1: one disease, 2: more than 2 diseases). Since 1997, we have conducted preoperative scoring and managed the unruptured cerebral aneurysms with scores of over 2 by observation, intravascular surgery or clipping surgery. Surgical results were evaluated using a modified Rankin scale (mRS). Before scoring, surgical complications exceeding mRS III occurred in 7.5% of cases, whereas this figure declined to 2.5% in the surgical results since 1997. When results of clipping surgery and intravascular surgery were compared, the former showed 3.8% and the latter showed 0% of complications exceeding mRS III.
The results indicate that clipping surgery combined with intravascular surgery improves surgical outcome for unruptured cerebral aneurysms with high risk.