Internal Carotid Artery Agenesis Associated with Contralateral Posterior Communicating Artery and Basilar Tip Aneurysms: A Case Report

Background: Absence of the internal carotid artery is an extremely rare congenital anomaly with a reported incidence of 0.01%. As with other anatomical vascular variants, they usually follow a silent course and are typically discovered incidentally. Case presentation: We report an unusual case of a 30 year old male medically free who presented to the emergency department with sided numbness involving both upper and lower limbs while he was swimming. Brain imaging revealed a congenital absence of the right internal carotid artery in association with basilar tip saccular aneurysm and right posterior communicating artery aneurysm. The patient treated successfully with endovascular stent-assisted coiling of the basilar artery and stenting of the right posterior communicating artery. Conclusion: The main significant impact this condition harbors is the high association with intracranial aneurysms secondary to hemodynamic stress on other intracranial arteries with compensatory increased flow. This case report supports this hypothesis and shows the complex endovascular management.