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How to read a C-spine film

While emergency physicians are increasingly utilizing C-spine CT (especially in high-risk patients and those already getting a head CT), familiarity with the reading of the cervical spine x-ray is a skill that falls solidly within the scope of the ED physician. Below we will review the ten steps to reading a c-spine xray. One way to remember these steps is AAABBBCs.

Steps: Adequacy Alignment AADI (anterior atlantodental interval) BDI (bsion dental interval) Base of dens Bony abnormalities Cartilage disks Cartliage facets Soft tissues Scan the periphery

Step 1: Adequacy

Make sure that you can visualize the entire C spine to the C7-T1 interface.

Failure to visualize the seventh cervical vertebra and the CT/TI junction is the most common error made in the radiographic assessment of cervical spine injury.

Step 2: Alignment

Make sure there is no rotation present (rotation will be seen when left and right diamond-shaped lateral masses of each vertebra are not superimposed as below).

alignment-1

Make sure the the anterior longitudinal ligament line (also anterior vertebral line), posterior longitudinal ligament line (also posterior vertebral line), spinolaminar line and tips of spinous processes fall along a smooth and continuous line.

Step 3: AADI (anterior atlantodental interval)

Make sure the anterior atlantodental interval (also called pre-dental space) is less then 3 mm in adults and less than 5 mm in children.

Step 4: BDI (basion dental interval)

Make sure the basion-dens interspace is less than 12 mm (see examples below of a normal and abnormal BDI).

Step 5: Base of dens

Make sure the ring of C2 is smooth and continous.

base_of_dens-1

Check for a "fat C2".

base_of_dens-2

Step 6: Bony abnormalities

Inspect each bone (vertebral body, pedicle, articular mass, lamina, spinous process) from top to bottom.

*The majority of missed fractures are at the upper and lower cervical segments.

Step 7: Cartilage disks

Check for uniform disk spaces between vertebrae.

Cartilage Disks

Step 8: Cartilage facets

Make sure that the space between opposing facets is parallel and that joint space is uniform

Step 9: Soft Tissues

Make sure that the pre-vertebral tissue is within the expected size range.

  • 6 mm at C2
  • 22 mm at C6
  • Or above C4: soft tissues less than 50% of the width of a vertebral body
  • below C4 the limit is one full vertebral body width.
soft tissues

Step 10: Scan the periphery

  • Briefly view base of skull, mandibles, anterior neck
  • Also evaluate sinuses, occiput, mandible
  • Airway: epiglottis, hyoid bone, tracheal air shadow
  • Finally, check for foreign bodies

Open Mouth View

Same system for open mouth view

  • Adequacy/alignment: no overlap by teeth or skull base, dens, spinous process, lateral masses are all symmetrically aligned
  • Bones: base of dens, body of C2, C1 lateral masses
  • Cartilage: articular spaces between C1 and C2 are even and the image that's now there.
open mouth view

AP View

Same system for AP films

  • Adequacy/alignment: spinous processes midline and evenly spaced
  • Bones: vertebral bodies, uncinate processes, lateral masses, spinous processes
  • Cartilage: disk spaces uniform in height to the end
AP View