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- Discussion:
    - soft tissue swelling is indirect indicator of significant trauma, esp when the soft tissue swelling is above the epiglottis;
    - retropharyngeal soft tissue swelling should not exceed:
         - anterior to C3 should not exceed 3 mm.
         - if > than 5 mm at C3 consider minimally displaced C2 fracture;
         - w/ children, crying increases the C3 distance;
         - below C4 the thickness varies from 8 to 10 mm & is less reliable;
    - distance between tracheal air column & anterior aspect of vertebral body should be No greater than:
         - Adults: no > than 7 mm at C2 or 22 mm at C6;
         - Child: no > than 14 mm at C6
              - during x-ray child should be in neutral or sl extension and w/ a full inspiration;
              - fullness and laxity of child's prevertbral soft tissues may simulate traumatic swelling if film is obtained during expiration or flexion;
- Diff Dx:
    - Hyperextension dislocation
         - combination of prevertebral soft tissue swelling in assoc w/ normal alignment of C spine suggests Hyperextension dislocation;
    - Hangman's frx
    - Jefferson frx