Anomalous location of the vertebral artery in relation to the neural foramen. Implications for cervical transforaminal epidural steroid injections.

Objectives: Evaluate the prevalence of an anomalous posterior vertebral artery (VA) in the neural foramen and to see if any factors might correlate with proximity of the VA to needle location in a cervical transforaminal epidural steroid injection (CTFESI).

Methods: A radiologist with subspecialty training in neuroradiology documented VA location in relation to the neural foramen on axial views of 198 consecutive computed tomography angiograms done for various reasons, 11 were excluded because of poor imaging or occluded VA. The levels of C2-3 through C6-7 were evaluated, where the VA courses within the foramen.