Although INR 3.0, other causes of intraparenchymal and subarachnoid hemorrhage need to be considered.  Review of history indicated the thoracic surgery was performed on background of bacterial endocarditis. 

CTA source images (not shown) did reveal the aneurysm immediately deep to the cranial vault, at an unusual site for typical aneurysms, and with artefact from skull vault potentially leading to missed diagnosis.

The DSA shows an aneurysm at an atypical site - on these images alone a mycotic (infective) aneurysm would be proposed without additional history.  Once the additional history was known, the diagnosis was almost certain and was subsequently surgically confirmed.

In this case the very distal location, tortuous cervical ICA access led to the consensus decision to manage with surgical clipping.  Once thought a relative contraindication to endovascular treatment, infective aneurysms have now been treated with coil embolization.