Vertebral artery position in the setting of cervical degenerative disease: implications for selective cervical transforaminal epidural injections.

Cervical transforaminal epidural injections (C-TfEI) are commonly performed in patients with cervical radiculopathy/pain. C-TfEIs are typically performed without incident but adverse events can occur. Using CT-fluoroscopy-guided C-TfEI, we commonly observe the vertebral artery in proximity to the target injection site. The purpose of this study was to assess the position of the vertebral artery relative to the typical C-TfEI injection point. CT-fluoroscopy-guided C-TfEIs were performed at 70 levels in 68 patients with radiculopathy/neck pain (age range 19-83 yrs, mean 50.6 yrs). Degenerative neural foraminal narrowing at each level was characterized (normal-to-mild, moderate, severe). Vertebral artery position was categorized as: anterior (normal), partially covering neural foramen, complete/near-complete covering the neural foramen. Additional measured variables included angle of needle trajectory, foraminal angle, and whether or not needle trajectory intersected with the vertebral artery. Foraminal vertebral artery covering correlated with severity of foraminal degenerative narrowing (p=0.003). Complete/near-complete covering was seen in: 65% severely narrowed foramina, 30% moderately narrowed foramina and 10% normal/mildly-narrowed foramina. Needle trajectory intersected with the vertebral artery in 30 of 70 injections (46%) by CT-fluoroscopy, frequently associated with shallow (lateral) approaches. Foraminal angle, approximating oblique fluoroscopic technique, suggests needle trajectory intersection with the vertebral artery in 27 of 70 foramina (39%). Vertebral artery position is commonly displaced into the foramen in patients with advanced cervical degenerative disease. Operator awareness of altered vertebral artery position is important for determination of optimal needle trajectory and tip placement prior to injection in patients undergoing C-TfEI.