Left Internal Carotid Artery Agenesis Associated with Basilar and Left Vertebral Artery Aneurysm

Agenesis of the internal carotid artery (ICA) is a rare congenital anomaly. Most of the patients are asymptomatic and it is usually discovered incidentally by computed tomography (CT) or magnetic resonance imaging (MRI). There is close association of the cranial aneurysms and subarachnoid hemorrhage with ICA agenesis. We present a case of a 61-year-old male with left ICA agenesis associated with basilar artery and left vertebral artery aneurysms. The patient complained of headaches and numbness on the right-side of the face. Physical examination showed high blood pressure (210/90 mmHg). Neurological examination revealed nystagmus and decreased sensation on the right-side of the face. Agenesis of left ICA, left carotid canal with basilar and left vertebral artery aneurysms were demonstrated incidentally using CT, MRI, and digital subtraction angiography, as a part of an evaluation for suspected cerebrovascular accident.