Risk Assessment of Intracranial Aneurysm Remnants After Microsurgical Clipping Based on 3D-Digital Subtraction Angiography

BACKGROUND AND OBJECTIVES: Several factors [such as intracranial aneurysm (IA) morphologic characteristics, location, rupture status, or use of multiple clips] have been suggested to predict the risk of incomplete IA clipping. However, the assessment of completeness of IA occlusion has been based on 2-dimensional-digital subtraction angiography, which fails to detect >30% of remnants when compared with 3-dimensional-digital subtraction angiography (3D-DSA) imaging. We aim to identify risk factors for IA remnants after microsurgical clipping based on 3D-DSA imaging. METHODS: A consecutive series of 329 clipped IAs in 305 patients who underwent 3D-DSA immediately after clipping was evaluated for the presence of IA remnants. Multivariable regression analyses were performed to assess the potential risk factors of IA-related morphologic features, location and rupture status, and number of clips on the odds of remnant presence. RESULTS: After clipping 329 IAs, 76 aneurysm remnants were present based on 3D-DSA. Pretreatment IA size was the only robust risk factor associated with the presence of remnants (P < .001). Multivariable regression analysis showed no association between IA rupture status (subarachnoid hemorrhage) (P = .37), IA location (P = .11), use of multiple clips (P = .07), broad-based IAs (P = .38), IA shape (P = .77), or IA calcification (P = .97). CONCLUSION: When assessed by 3D-DSA, the incidence of IA remnants after clipping is higher than reported in the literature. In our series of 3D-DSA based imaging, preoperative IA size was the only robust independent risk factor for incomplete clipping, and these cases must be followed closely.