Atlanto-occipital dissociation injury

Case contributed by Matt Skalski


Motorcycle accident with severe poly-trauma.

Patient Data

Age: 35 years
Gender: Male

The atlantooccipital joints are widened bilaterally, with an increased basion-dens interval to 13mm (normal < 12mm). The prevertebral soft tissues are enlarged due to extensive swelling anterior to C1-4. There is also swelling noted posterior to C1/2 in the interspinous region.  No fractures are identified. 

Incidentally noted is an ununited posterior arch of C1 (a common normal variant of no clinical significance), not to be confused with a fracture. 

Increased basion-dens interval (orange line) and widened atlantooccipital joints (orange curved arrows) are indicated.

Case Discussion

It is unusual for an adult to survive an atlantooccipital dislocation, but none-the-less imperative that the findings are recognized immediately, as they can be subtle (when the patient survives long enough to make it to imaging.) This patient survived and was placed in a halo. 

Case courtesy of Dr. Deborah Forrester

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