High-Entry Vertebral Artery Variant during Anterior Cervical Discectomy and Fusion

Anterior surgical approaches to the cervical spine have allowed for treatment of common and complex pathologies with excellent outcomes. During the approach, complications can result from injury to the surrounding structures. The transverse processes usually protect the vertebral artery (VA) as it enters at C6 and courses cranially through the transverse foramina to C2 (referred to as the V2 segment). This is a case report of a patient who presented with myeloradiculopathy attributed to a C4-C5 disc herniation, severe canal stenosis, and marked bilateral neural foraminal stenosis. Preoperative imaging showed the right VA entering the C4 transverse foramen. This anatomic variant on a routine MRI led to further imaging and precautions when performing an uneventful anterior cervical discectomy and fusion (ACDF) at C4-C5. A high VA entry point into the transverse foramen above C6 could increase the risk of iatrogenic vascular injury in anterior approaches to the cervical spine. Rarely reported, the currently presented case describes a patient with a C4 right VA entry variant and highlights the importance of proper surgical planning.

Vertebral Artery Arteriovenous Fistula: Complication Following Cervical Spinal Fusion

We report a rare case of extradural arteriovenous (AV) fistula of the right vertebral artery and vein following cervical spinal fusion. A 68-year-old female patient presented with complaints of a persistent buzzing sound in her right ear for 4 months that began following cervical spinal fusion surgery via an anterior approach. A right-sided bruit was noted and the patient was referred for a carotid duplex study. A carotid duplex was performed on a Philips IU22 using a 9-3 linear array transducer. The exam revealed a high-velocity vertebral artery waveform with spectral broadening and venous component suggestive of an AV fistula. Magnetic resonance angiography (MRA) of the neck confirmed a right extradural AV fistula at the level of C4 between the right vertebral artery and vein. The patient subsequently underwent angiography and coil embolization of the right vertebral artery. Postembolization angiography revealed resolution of the AV fistula and occlusion/near occlusion of the vertebral artery distal to the embolization. While vascular injuries are a known complication of spinal surgery using the anterior approach, it is rare for them to present as a late finding. Duplex evaluations of the carotid arteries for patients’ subjective noise complaints often do not reveal significant pathology; though in cases involving a history of prior surgical intervention, ultrasound may be useful in identifying iatrogenic vascular injury.