Fig. 5
Vertical subluxation with spinal cord compression. MRI of the cervical spine in a 69-year-old woman with advanced peripheral RA, neck pain and clinical signs of myelopathy. (a) Sagittal STIR, (b) sagittal T1 and (c) axial T2 fat-saturated (FS) images show erosion of the dens and protrusion of the tip into the occipital foramen causing compression of the spinal cord, which exhibits irregular signal intensity (white arrows). The osseous spinal canal has a width of approximately 7 mm (black line). There is heterogeneous signal intensity pannus surrounding the dens compatible with a mixture of fibrotic and oedematous pannus tissue (black arrows) in the widened space between the dens and the anterior arc of the atlas