Impact of aneurysm shape on morbidity after clipping of unruptured intracranial aneurysms

Complex aneurysm shape is a predominant risk factor for aneurysm rupture but its impact on clinical outcome after clipping remains unclear. The objective of the present study was to compare complications and morbidity after clipping of unruptured single-sac aneurysms (SSAs) and aneurysms with multiple sacs (MSAs). A retrospective, single-center study was conducted for patients that were treated between 2010 and 2018. We analyzed surgical parameters, treatment-related complications, and morbidity, defined as any increase in the modified Rankin scale at 3-month follow-up. We identified 101 patients (mean age: 52.9 +/- 10.5 years) that underwent clipping for 57 SSAs and 44 MSAs. The two groups were comparable regarding aneurysm size and neck width. Clipping of MSAs was associated with a longer operation time (p = 0.008) and increased use of intraoperative indocyanine green (p = 0.016) than SSAs. Complications occurred more often in the MSA group (29.5%) than in the SSA group (14.0%; p = 0.057). Morbidity was significantly higher in the MSA group (20.5%) than in the SSA group (3.5%, p = 0.009). In the univariate analysis, the odds of morbidity were 7.1 times greater for MSAs than for SSAs (95% CI 1.4-34.7). Morbidity after microsurgical clipping is significantly increased in MSAs as compared to SSAs. This may be attributed to a more difficult clip placement with stronger manipulation of the aneurysm dome and the surrounding brain tissue.