Transverse and oblique course of the vertebral artery over the medullospinal junction

Purpose The vertebral artery (VA) pierces the dura mater and continues with the intradural V4 segment. Once entered into the dura mater, the VA ascends from the infero-lateral to the antero-superior side of the medulla. Scarce reports of VAs compressing the medullospinal junction (MSJ) are available. We therefore aimed to determine the incidence of a course of the AV over the MSJ. Method One hundred sixty-two archived CT angiogram files were documented in the study. We recorded the cases in which the VA crossed the MSJ. We assessed the VA as dominant, non-dominant or co-dominant. Results In 32 cases (19.75%), we identified intradural AVs on the ventral side of the MSJs. The incidence of this course of the VA was 17.1% in males and 23.81% in females. Of the 32 cases, the VA was non-dominant in 6, dominant in 14, and co-dominant in 12. Conclusion The VA course over the MSJ is not rare. Therefore, when specific neurological signs of MSJ or medulla compression are found, the course of the VA should be documented on CT or MRI angiograms.