Internal carotid artery agenesis with stenosed intercavernous anastomosis: a case report.

We report a rare case of internal carotid artery agenesis with stenosed intercavernous anastomosis. A 59-year-old male patient presented with a new infarction in the left basal ganglia. Magnetic resonance angiography and cerebral angiography showed that the right internal carotid artery disappeared from the origin to the foramen lacerum segment, and there was an anastomotic artery with severe stenosis passed through the floor of the sella and in front of the cavernous sinus. The right A1 segment of the anterior cerebral artery was absent and A2 segment was supplied by the normal contralateral internal carotid artery via the anterior communicating artery.