[Ruptured P1-2 junction aneurysm associated with bilateral agenesis of the internal carotid artery].

We report a case of bilateral agenesis of the internal carotid artery which was revealed by oclulomotor palsy and subarachnoid hemorrhage. Angiography showed a ruptured aneurysm of the left P1-2 junction and bilateral absence of the internal carotid artery. In surgery, it was necessary to use temporary clipping several times to adjust the aneurismal clipping. Complete clipping easily compromised the middle cerebral circulation. This case suggested that STA-MCA bypass should be considered in the surgery of agenesis of the internal carotid artery in which the preoperative hemodynamic status is usually normal.