The C-Spine Injury with Increased Atlanto-Dental Interval
This was a case that Marcel presented to me, in which I killed the patient when I was unable to control the bleeding vertebral artery.
The point to this is the differential of the increased ADI – basically, you must think of ACUTE TRAUMA versus some other NONTRAUMATIC case.
The ACUTE TRAUMATIC injury with this x-ray finding is a transverse ligament rupture. I think this is quite rare, and certainly more uncommon than an odontoid fracture, which would be the more likely outcome from this sort of mechanism. In an adult, the ADI should be 4 mm or less (some say 3). Look for an avulsion on the CT scan. If a bony avulsion is documented by CT scan, the injury has a good chance of healing in a halo. If no avulsion is seen on CT, get an MRI to evaluate the ligament. If the ligament is ruptured, the injury is unlikely to heal, and should probably be fused primarily.
The NONTRAUMATIC causes would include rheumatoid arthritis, os odontoideum, Marfan’s or other connective tissue disorder like Ehler’s Danlos, Morquio’s syndrome, Down’s syndrome. You should think of these – PARTICULARLY RHEUMATOID. The injury that the patient has may not have much to do with their C1-2 instability.
In the case that Marcel presented me, the patient has some sort of rheumatoid disease, and the instability was actually chronic – he chose to treat the patient for symptoms only and is going to follow the instability along. I diagnosed it as an acute transverse ligament rupture (even though there was no avulsion on CT, and I did NOT order and MRI), and basically, after failing conservative Rx (put him in a halo), I bagged the vertebral artery during the C1-2 fusion and killed the patient.