Bilateral congenital absence of the internal carotid artery.

Bilateral congenital absence of the internal carotid artery was incidentally found in an 11-year-old boy. Magnetic resonance imaging showed a normal-appearing brain that was entirely supplied by the vertebrobasilar system, and CT confirmed the absence of the bony carotid canals. Although most reported patients with agenesis of both internal carotid arteries presented with cerebrovascular lesions, this case demonstrates that this rare malformation may be asymptomatic.