A 17-year-old boy experienced 2 transitory ischemic attacks with dysphasia, right hemiparesis, and visual disturbances. At the age of 2 years, he had undergone surgery to repair a complex congenital heart defect consisting of patent ductus arteriosus, patent foramen ovale, and dysplastic pulmonary valve with shunting and pulmonary hypertension. After the surgery, he was regularly observed by his cardiologists; his physical and mental development were normal.
On magnetic resonance angiography the patient's left internal carotid artery was missing, while the right internal carotid artery was hypoplastic (Figure, A). Computed tomography of the temporal bone showed the carotid canal was hypoplastic on the left side, which is highly suggestive of internal carotid artery agenesis (Figure, B). In the circle of Willis, the fetal type of collateral circulation was present, with the left middle cerebral artery supplied with blood from the basilar artery. Furthermore, the anterior communicating artery and both pericallosal arteries were arising from the anterior cerebral artery on the affected left side, while segment A1 was missing on the right (Figure, C). Aneurysms were not found. Echocardiography revealed no cardiac thrombi.
Slankamenac P, Jesic A, Zivanovic Z, Gebauer-Bukurov K, Bozic K. Agenesis of Internal Carotid Artery With Unusual Fetal Collateral Circulation. Arch Neurol. 2010;67(10):1280-1281. doi:10.1001/archneurol.2010.236