You might have Chiari’s syndrome if you have a “pathological Clivo axil and the deviation of cervical medullary junction around the dens”. The other possibility is basilar invagination which is somewhat similar to Chiari’s syndrome.
You can tell if you have transverse ligament incompetence of C1-2 by looking at the space between the front of the dens of C2 and the back of the front ring of C1 on flexion/extension X-rays (called the ADI or Atlanto-dens interval). If it enlarges greater than 3.5mm, you might have some laxity which can occur with Ehlers Danlos syndrome.
Dr. Corenman