Prediction of rebleeding from angiographic features in vertebral artery dissecting aneurysms.

To identify patient characteristics and angiographic features that predict high risk for rebleeding in vertebral artery (VA) dissecting aneurysms. We analyzed 62 patients treated for subarachnoid hemorrhage (SAH) from VA dissecting aneurysms (male: female, 46:16; mean age, 51.7 +/- 8 years). Univariate and multivariate stepwise logistic regression analyses were performed to assess relationships between rebleeding rate and age, gender, history of hypertension, sidedness of the aneurysm, angiographic configuration, and location relative to the origin of the posterior inferior cerebellar artery (PICA). Rebleeding occurred in 22 patients (37%), mostly within 24 h. Patients without rebleeding had favorable outcomes, while patients with rebleeding showed higher mortality. Angiographic patterns with high rebleeding rates included "stenosis and dilation" (50%), and "lateral protrusion" (43%), contrasting with "dilation and stenosis" (20%) and other types. Rebleeding also was likely in aneurysms proximal to or at the PICA origin (rate, 47% or 46%) than distal to the PICA origin (21%). Multivariate logistic regression analysis found two factors independently associated with rebleeding: angiographic pattern of the aneurysm (odds ratio 1.88:1, P=0.0366), and location relative to the PICA origin (odds ratio 4.93:1, P=0.028). High risk of rebleeding in VA dissecting aneurysms can be predicted by angiographic configurations such as "stenosis and dilation" and "lateral protrusion" and by location at or proximal to the PICA origin.