Agenesis, aplasia, and hypoplasia of the<unk>  carotid artery (ICA) are rare<unk>  anomalies, occurring in less than 0.01% of the population. Slightly more than 100 cases of<unk><unk>  of the ICA have been reported in the literature. The term<unk>  has been chosen to incorporate agenesis, aplasia, and hypoplasia of the ICA. The most common type of collateral flow is through the circle of Willis. Less commonly, collateral flow is provided via persistent embryonic vessels or from transcranial collaterals originating from the external carotid artery (ECA) system. Although many of these cases remain asymptomatic and go undetected, it is associated cerebral aneurysms. Also these anomalies have important implications during carotid endarterectomy and transsphenoidal hypophyseal surgery, and in the setting of thromboembolic disease.<unk><unk>  of the left<unk>  carotid artery
Congenital absence of the internal carotid artery
Kissing carotid arteries
Intracranial berry aneurysm
Cerebral arteriovenous malformation
Chronic white matter microvascular ischemic disease
Aneurysm of sinus of valsalva
Vertebral artery dissection
Vertebral artery disease