Assessment of the clipping efficacy of intracranial aneurysms: analysis of the employed methodology in relation to case difficulty

Objective: To assess intracranial aneurysms clipping efficacy ( CE) employing different angiographic techniques in relation to the case difficulty. Method: In the past 6 years, 152 patients harboring 179 aneurysms who underwent surgical clipping in our department were angiographically examined to confirm aneurysm occlusion. Intraoperative angiography ( IA), post-operative conventional ( PCA) and three-dimensional angiography were single or sequentially performed based on the surgeon's concern about case difficulty. The percentage of visualized angiographic abnormalities ( PVAA) assessing CE and their impact on corrective treatment were retrospectively analysed. Results: The PVAA of IA was 67.8% ( 19 of 28 aneurysms). Eighteen of them ( eight aneurysm remnants, four parent vessel stenosis, two distal branch occlusions and five clip slippage phenomena) underwent immediate corrective treatment ( clip reposition in 11 cases, complementary clipping in three cases and combined treatment in four cases). The impact on corrective treatment was 94.7%. The PVAA of PCA was 18.4% ( 33 of 179 aneurysms). Fifteen patients presented aneurysm remnants, six presented parent vessel stenosis, five presented distal branch occlusions and seven presented clip slippage phenomena. The impact of this technique on corrective treatment was 15.1% ( five of 33 angiographic abnormalities). In only one case, PCA demonstrated an aneurysm remnant which was missed on IA. Twenty patients were additionally examined with three-dimensional angiography. The impact on corrective treatment of three-dimensional angiography was 25% ( five of 20 examined patients with angiographic abnormalities). Conclusion: In pre-selected difficult cases, IA provides high PVAA and increased impact on corrective treatment. In non-selected patients, PCA shows low PVAA and reduced impact on corrective treatment. The complementary assessment with multiplanar three-dimensional angiography increases the impact on corrective treatment and facilitates decisions about the final case management.