Double Origin of the Posterior Inferior Cerebellar Artery: Anatomic Case Report.

Abstract

Double origin of the posterior inferior cerebellar artery is rare. It has important clinical implications especially in cases of aneurysms of the vertebral artery or the posterior inferior cerebellar artery. Several radiologic reports of this variant exist. However, no anatomic illustration of this rarity exists in the literature. This brief report provides the first anatomic illustration of this important variation of the vertebrobasilar system. A cadaveric specimen was prepared for dissection. A far lateral craniotomy was performed on the right side. While exploring the right cerebellomedullary cistern, 2 separate origins of the posterior inferior cerebellar artery were found from the vertebral artery as the caudal and rostral trunks that joined to form the distal posterior inferior cerebellar artery trunk at the tonsillomedullary segment. Microscopic and endoscopic illustrations are provided. To the best of our knowledge, this is the first anatomic report on the double origin of the posterior inferior cerebellar artery. Cadaveric illustration of this variant helps with understanding its anatomic relationship with adjacent neurovascular structures of the cerebellomedullary cistern including the perforating arteries and the lower cranial nerves.