Intraoperative Aneurysm Rupture During Microsurgical Clipping: Risk Re-evaluation in the Post-International Subarachnoid Aneurysm Trial Era

OBJECTIVES: Intraoperative aneurysm rupture (IOAR) is a common complication during intracranial aneurysm (IA) surgery. In light of the paradigm shift regarding IA selected for clipping in the post-International Subarachnoid Aneurysm Trial (ISAT) era, we aimed to evaluate the risk factors and effects of WAR in an institutional series of clipped ruptured IA (RIA) and unruptured IA (UIA). MATERIAL AND METHODS: All IAs treated with microsurgical clipping at our institution between 2003 and 2016 were eligible for this study. Demographic, clinical, and radiographic factors were correlated with occurrence of IOAR in univariate and multivariate analyses. The effect on outcome was analyzed for RIA and UIA separately. RESULTS: Nine hundred and three clipped lAs were included in the final analysis (538 UIA and 365 RIA). IOAR occurred in 163 cases (18.1%), mostly during clipping of RIA (37.5% vs. 4.8%) In multivariate analysis, ruptured status (adjusted odds ratio [aOR], 10.46; P < 0.001), sack size (aOR, 1.05 per mm increase; P = 0.038) and IA location in the anterior communicating artery (aOR, 2.31; P < 0.001) independently predicted IOAR. For RIA cases, IOAR was also independently predicted by rebleeding before therapy (aOR, 3.11; P = 0.033) and clinical severity of subarachnoid hemorrhage (aOR, 1.18 per WFNS grade increase; P = 0.049). IOAR independently predicted poor outcome (aOR, 1.83; P = 0.042) after RIA surgery. In turn, IOAR affected only the risk for cerebral infarct (OR, 3.75; P = 0.003) and incomplete IA occlusion (OR, 3.45; P = 0.003) for UIA cases, but not the outcome (P = 0.263). CONCLUSIONS: IOAR was independently predicted by the ruptured status, location, and size of IA and by initial severity of aneurysmal bleeding and pretreatment rebleeding. The influence of IOAR differed between RIA and UIA cases.