Introduction: Lateral alanto-axial joint injections are commonly performed for cervicogenic headache (1). While complications during transforaminal cervical injections have been well described (2,3,4,5), no reports of complications during lateral C1-2 injections are published. We present a case of unique intravascular contrast uptake during a lateral C1-2 joint injection. Case: A 79 year-old female presented with right atlanto-axial arthropathy. A 25 gauge blunt-tipped needle was introduced from a posterior approach to the dorsal lateral aspect of the C1-2 joint. Proper needle position was confirmed with AP and lateral views. Instillation of non-ionic contrast iohexol revealed vascular uptake with anterior spinal canal spread with a hint of arterial spread on digital subtraction angiography. The needle was repositioned medially, and a paresthesia was reported in the C2 distribution. A vascular pattern was again seen with ventral spinal canal spread which tracked caudally and appeared to communicate with a vertebral or deep cervical artery. The procedure was aborted, and the patient was escorted to recovery in satisfactory condition without sequelae. Discussion: The vertebral arteries lie in close proximity to the lateral atlantoaxial joint. There are multiple arterial anastamoses described between vertebral, occipital and deep cervical arteries(6). Previous cadaveric studies demonstrated that the ascending and deep cervical arteries contribute to the anterior spinal and vertebral arteries via segmental medullary anastomoses (7). Notably, transforaminal injections of particulate steroids has caused cerebellar injury and cortical blindness(8). We believe the noted vascular uptake was of one of these anastamoses, likely between the anterior spinal artery and the vertebral or deep cervical artery. Conclusion: Given the high degree of variability, vascular injection during lateral C1-2 injections are common. Digital subtraction imaging has clear advantages for avoidance of vascular injections. Only careful interpretation of the contrast shadow will keep a vigilant operator from injecting a steroid particulate into a vessel.