Occipital Artery to Posterior Medullary Artery Bypass During Clipping of a Dissecting V4 Vertebral Artery Aneurysm: 2-Dimensional Operative Video

A stroke in the territory of a large dominant medullary branch of the vertebral artery-we refer to as posterior medullary artery (PMA)-can be devastating.1-3 The medullary branches (MB) (n = 1-6) arise from the V4 segment of the vertebral artery or posterior inferior cerebellar artery to supply the posterior dorsal area of the medulla oblongata and anastomose with the anterior spinal artery and ascending branch of the posterior spinal artery.4 The presence of a PMA of a caliber that can be detected in an angiogram must be preserved and should influence treatment strategy according to a flow -out principle. The flow-out principle involves preserving linear flow (ie, not static or stagnant) into a perforating artery during clip reconstruction. We report a case where a large PMA arose from an enlarging dissecting vertebral artery aneurysm. The endovascular team referred the patient to our institution for clipping and direct revascularization of the involved PMA. A left far lateral craniotomy was performed, and the occipital artery was harvested.5,6 An occipital artery to PMA bypass allowed for proximal occlusion of both the vertebral artery and the PMA. This strategy preserved blood supply to the PMA territory and allowed stagnant flow to thrombose the vertebral artery aneurysm, which was proximal to the take-off of the posterior inferior cerebellar artery. This is a rare case where the MB territory was supplied by a PMA. The patient tolerated the procedure well and was discharged without neurological deficits. The patient consented to the procedure and to the publication of his/her image.