MRI
Sagittal T2
Axial T2
Sagittal T1
Axial T2 fat sat
Partial fusion of anterior arch of atlas with clivus. Posterior arch of atlas is not visualized separately and is likely fused with occiput.
Atlantoaxial subluxation is seen with atlantodental interval being approx 9 mm.
Basilar invagination is also seen with superior migration of dens of C2, projecting above foramen of magnum causing severe compression of cervicomedullary junction and upper cervical cord.
Hyperintensities are seen in cervicomedullary junction and upper cervical cord at C2 level.
Erosion/cystic change seen in dens of C2 with tiny calcifications at anterior aspect of dens and heterogeneous soft tissue in atlantodental interval - likely degenerative changes. Possibility of inflammatory arthritis, example rheumatoid appears less likely.
C2-C3 block vertebra seen.