PMC7771403_01
(a) T2 sagittal MR craniovertebral junction showing the presence of BI with severe compression of the spinal cord. No evidence of Chiari or syrinx. The axial (b), sagittal (c and d), and coronal (e) source images of CT angiogram of neck vessels show an abnormal tortuous and retropharyngeal course of bilateral cervical internal carotid arteries, coming nearby at C1-2 level (yellow arrow). Note the atlantooccipital assimilation and basilar invagination. The volume rendering technique image (f) shows the proximity of the carotids in relation to C1-C2: "Kissing carotids."
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F1
The MR showed atlantoaxial dislocation (AAD) with severe compression of the spinal cord at the craniovertebral junction (CVJ) [Figure 1a]. The CT-CVJ and CT angiography (CTA) [Figure 1b-e] demonstrated AAD with basilar invagination (BI) and a partially occipitalized C1 arch [Figure 1c and d]. The CT angiography (CTA) and 3D-CT with volume rendering technique [Figure 1f] demonstrated that both carotid arteries had an abnormal elongated and tortuous course and were "kissing" (lying very close to each other) anteriorly at the C1-C2 level.