Abnormal aneurysmal dilatation of the internal carotid artery on angiography without abnormal finding at surgery: a case report.

After trauma, the next most common cause of subarachnoid hemorrhage (SAH) is aneurysm rupture. Aneurysms can be of any size and shape and most commonly are found at the anterior or posterior communicating cerebral arteries. Although magnetic resonance angiography is improving in diagnostic accuracy, routine catheter angiography is still considered the "gold standard" for diagnosis. We report a case in which an abnormal dilatation of the supraclinoid internal carotid artery was diagnosed as an aneurysm following catheter angiography; at surgery this area appeared normal.