Large dorsal internal carotid artery aneurysm--report of two cases.

Two patients with unusually large dorsal internal carotid artery aneurysms manifesting as subarachnoid hemorrhage are described. Surgery in both cases resulted in intraoperative rupture of the sac. The outcome was poor in the first patient and excellent in the second. The importance of wide exposure of the proximal and distal vasculature to the aneurysm, subpial dissection of the frontal and temporal lobes not to injure the fragile aneurysmal dome, and parallel clipping was emphasized for this rare type of aneurysm.