Nonvisualization of the Internal Carotid Artery on Computed Tomography Angiography: Discussion of Two Cases with Review of Literature

Abstract

Nonvisualization of the internal carotid artery (ICA) on cross-sectional imaging studies can be due to congenital (dysgenesis of the ICA) or acquired (complete occlusion of ICA) causes. We report two cases, one with absent carotid canal on bone window setting of computed tomography (CT) suggestive of congenital cause and the other with normal carotid canal, suggesting acquired cause. Development of aortic arches with six pathways of collateral circulation in brain is also discussed.

Internal Carotid Artery Aplasia in a Patient With Nail-Patella Syndrome

“…To date, a few more than 100 cases have been reported, 8 most were diagnosed incidentally late in life or during a workup for ischemic or hemorrhagic stroke. 9,10 Unilateral dysgenesis of the ICA is more common than bilateral, with the left ICA being affected 3 times more often than the right ICA. 7 Congenital ICA dysgenesis is associated with other abnormalities, commonly with anomalous intracranial vascular communications and ill-formed ipsilateral bony carotid canal.…”

“…The ventral segment becomes the embryonic ventral pharyngeal artery and fuses with common carotid artery while distal segment gives rise to intermediate arteries which reform to reconnect with the ventral segment and giving rise to the external carotid artery system by the 40th embryonic day of life. 10,[15][16][17] Early human cerebrovascular development is a complex process under the tight control of multiple homeobox genes, oncogenes, gene promoter methylation states, and protein products such as transcription factors, cytokines, and growth factors. 12 The complex networked protein-protein and proteingene interactions pace embryonic growth, instruct normal body patterning, and lay foundation of numerous organ systems including normal formation of craniofacial morphology, skull development, and adult cerebrovascular derivation of the primitive pharyngeal arches.…”

“…To date, a few more than 100 cases have been reported, 8 most were diagnosed incidentally late in life or during a workup for ischemic or hemorrhagic stroke. 9,10 Unilateral dysgenesis of the ICA is more common than bilateral, with the left ICA being affected 3 times more often than the right ICA. 7…”

“…The ventral segment becomes the embryonic ventral pharyngeal artery and fuses with common carotid artery while distal segment gives rise to intermediate arteries which reform to reconnect with the ventral segment and giving rise to the external carotid artery system by the 40th embryonic day of life. 10,15 -17…”

Asymptomatic Complete Occlusion of Extracranial Internal Carotid Artery: A Case Report

“…У пожилых пациентов окклюзия внутренней сонной артерии часто вызывается атеросклерозом, который в основном развивается в ее проксимальной части. Формированию атеромы способствуют особенности гемодинамики в области бифуркации общей сонной артерии [7].…”