Unique vascular structures of a radicular arteriovenous fistula at the craniocervical junction along the first cervical spinal nerve: A case report

BACKGROUND: An arteriovenous fistula (AVF) at the craniocervical junction (CCJ) is a rare vascular malformation. Definitive diagnosis and curative treatment of CCJ AVF are challenging. CASE DESCRIPTION: A 77-year-old man presented with subarachnoid hemorrhage. Cerebral angiography showed an AVF at the CCJ, which drained into a radicular vein. The lesion was fed by a vertebral artery, anterior and lateral spinal arteries (LSAs), and the occipital artery (OA). There were two unique structures: the LSA originating from the posterior inferior cerebellar artery of the extracranial V3 segment and the OA feeding the shunt. Curative treatment involved two steps: endovascular embolization of feeders using Onyx and surgical shunt disconnection. Feeding arteries were blackened by Onyx, which helped identify the location of the shunt. The shunt was located behind the first cervical (C1) spinal nerve, and the draining vein was confirmed on the deep side of the nerve. A clip was applied to the draining vein distal to the shunt. Tiny vessels supplying the shunt were then coagulated referring to blackened arteries. CONCLUSION: A radicular AVF at the CCJ along the C1 spinal nerve had unique vascular structures. Definitive diagnosis and curative treatment were achieved by combining endovascular embolization using Onyx and direct surgery.