Tehran University of Medical Sciences Case Reports in Clinical Practice 2538-2683 2 3 2018 02 17 79 81 EN Payam Sarraf Associate Professor, Department of Neurology AND Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran. Dina Motamedi Resident, Department of Neurology AND Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran. Hosien Ghanaati Professor, Department of Interventional Radiology AND Advanced Diagnostic Interventional Radiology Research Center, Tehran University of Medical Sciences, Tehran, Iran. Arman Habibi Resident, Department of Neurology AND Iranian Center of Neurological Research, Tehran University of Medical Sciences, Tehran, Iran. 2017 10 04 2017 10 29 Bilateral extracranial internal carotid artery occlusion is a rare cause of transient ischemic attacks and stroke. In this situation, usually posterior circulation is the main source of brain blood supply. Insufficient posterior circulation with bilateral internal carotid artery is scarce, and its clinical picture in this condition is unpredictable. A 64-years-old man was admitted with recurrent transient ischemic attacks as hemiparesis (right hemiparesis except for one which left hemiparesis). Evaluations disclosed bilateral extracranial internal carotid artery occlusion accompanied with hypoplastic left vertebral artery and about 90% of stenosis in right vertebral artery as a main source of brain blood supply. This is a rare of case stenotic right vertebral artery as the only source of anterior and posterior brain blood supply, in absence of persistent neurologic sign, that has not been reported by now. https://crcp.tums.ac.ir/index.php/crcp/article/view/138 https://crcp.tums.ac.ir/index.php/crcp/article/download/138/84