Fig. 1

Ruptured left internal carotid artery dorsal variant aneurysm. a Head CT scan demonstrating diffuse, hyperdense subarachnoid hemorrhage. b Sagittal reconstruction of a CTA of the left internal carotid artery, which did not demonstrate the aneurysm. The aneurysm was also not identified on axial or coronal projections. c Left internal carotid artery digital subtraction angiogram demonstrating a 2.6 × 1.2-mm blister aneurysm (white arrow)