A Case Report: Entrapment of the Vertebral Artery between the Skull and the First Cervical Vertebra during Head and Neck Rotation

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Introduction: Entrapment of the Vertebral Artery between the skull and the first cervical vertebra during head and neck rotation may be difficult to assess, much less quantify. Prior investigations have demonstrated that a dynamic axial Computer Tomography scan, while the patient maximally rotates the head right and left, can be used to evaluate and quantify the amount of residual overlap between the inferior articulating facet of the first cervical vertebra and the superior facet of the second vertebra, as an index of ligamentous laxity at the joint. In the present Case Report, we assessed the possibility of entrapment of the Vertebral Artery between the skull and the bow of the first cervical vertebra during hyper-rotation of the cervical spine. By combining the results from a dynamic axial Computer Tomography scan of the upper cervical spine with an Angiography, the results enabled the interpreter to evaluate the course of the blood vessels through and past the skeleton during cervical spine hyper-rotation. Methods: The Angiography images were obtained with the patient scanned in specific positions on the scanning table as directed and positioned by the supervising clinician. 3D Volumetric Angiography scans were reviewed using RadiAntViewer software using both 3D and cross-sectional imaging techniques. Result: This Case Report demonstrated a unilateral compression of the Vertebral Artery, left side with the head and neck in right rotation, estimated to 47 % of the total lumen. In neutral position, the lumen of the Vertebral Arteries, right and left side, were completely open. Discussion: This result suggests a potential point of mechanical stress where the skull could be impinging on nearby structures, possibly affecting neurological and/or vascular components. The findings from these images suggest a relationship between cervical spine movement and potential vascular complications. The described compression appears to be related to over-rotation of the first cervical vertebra along with hyperextension of the skull. Conclusion: This case report highlights the relationship between upper cervical spine biomechanics and vertebral artery compression, showing that combined rotation and extension can lead to unphysiological compression between the skull and first vertebra. It underscores the value of positional cervical spine CT and CTA as useful tools for diagnosing potential vertebral artery compression.