Ruptured saccular aneurysm of a dolichoectatic internal carotid artery in a patient with agenesis of the contralateral internal carotid artery--case report.

A 42-year-old woman presented with very rare cases of ruptured saccular aneurysm of a dolichoectatic internal carotid artery (ICA) associated with agenesis of the contralateral ICA manifesting as sudden onset of severe headache and nausea without neurological deficits. Angiography and three-dimensional computed tomography demonstrated intraventricular hemorrhage with slight subarachnoid hemorrhage and dolichoectasia of the right ICA with agenesis of the contralateral ICA, as well as a saccular aneurysm of the ectatic right ICA. The aneurysm neck was clipped successfully.