RT Journal Article SR Electronic T1 Congenital Absence of the Internal Carotid Artery: Case Reports and Review of the Collateral Circulation JF American Journal of Neuroradiology JO Am. J. Neuroradiol. FD American Society of Neuroradiology SP 1953 OP 1959 VO 22 IS 10 A1 Curtis A. Given II A1 Frank Huang-Hellinger A1 Michael D. Baker A1 Neeraj B. Chepuri A1 P. Pearse Morris YR 2001 UL http://www.ajnr.org/content/22/10/1953.abstract AB Summary: Absence of the internal carotid artery (ICA) is a rare congenital anomaly. The embryology of the ICA and the common collateral pathways associated with its congenital absence are reviewed, with four new cases provided for illustration. While collateral blood flow may allow these patients to remain asymptomatic, two of our patients presented with transient ischemic attacks. Recognition of this anomaly has important implications during planned carotid or transsphenoidal surgery, in thromboembolic disease, and in the surveillance and detection of associated cerebral aneurysms.