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Head & Neck

Craniocervical Junction Trauma: Ligaments, Not Just Bones

Fellowship-level neuroradiology teaching by E. Brooke Schrickel, MD. Open this topic in the interactive reading room →

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Core clinical idea

At the craniocervical junction the grave, potentially fatal injury is often purely ligamentous with no fracture — because the CCJ is held by ligaments, not bony interlock. Don't clear it on bones alone: hunt malalignment and abnormal distances, and chase the associated cord and vascular injuries.

Bottom line

At the craniocervical junction the grave injury is often purely ligamentous with no fracture — clear it on alignment and distances, not bones, and chase the associated cord and vascular injury.

Core workstation questions

  • Have I cleared this on alignment and distances, or only on 'no fracture'?
  • Are the key distances increased — basion–dens, condyle–to–C1 lateral mass, atlanto-dental interval?
  • If I found AOD, did I measure for atlanto-axial dislocation too (they coexist)?
  • Did I check coronals for the medial condyle avulsion and the odontoid base fracture?
  • Given any CCJ ligamentous concern, have I prompted MRI for cord/ligaments and imaging for vertebral artery injury?
  • Is this asymmetric dens–lateral-mass distance real, or just head rotation — and is it supported by any other sign?

What changes reporting / management

  • Do not clear the CCJ on absence of fracture; report instability when distances/alignment are abnormal even with intact bone.
  • AOD signs: increased basion–dens distance, increased skull-base-to-C1 posterior arch, increased occipital condyle–to–C1 lateral mass (atlanto-occipital interval).
  • Atlanto-axial dislocation signs: increased atlanto-dental interval, transverse ligament disruption, abnormal C1–C2 signal/edema.
  • Prompt MRI for ligaments and cord, and vascular imaging for vertebral artery injury, when CCJ ligamentous disruption is suspected.
  • Find one dislocation pattern, deliberately measure for the other — AOD and atlanto-axial dislocation coexist.

Practical traps

  • Clearing the CCJ on 'no fracture' and missing a purely ligamentous, unstable injury.
  • Missing the medial occipital condyle avulsion on axials (check coronals).
  • Over-calling asymmetric dens–lateral-mass distance caused by head rotation when unsupported by other signs.
  • Stopping at the osseous classification without evaluating distances, ligaments, cord, and vessels.

Teaching pearls

  • No fracture does not clear the CCJ — the lethal injury can be purely ligamentous.
  • Increased basion–dens distance should make you think atlanto-occipital dislocation.
  • AOD and atlanto-axial dislocation travel together — find one, measure for the other.
  • The medial occipital condyle avulsion hides on axials — check the coronals.
  • Asymmetric dens–lateral-mass distance is a soft sign — head rotation fakes it; trust it only in company.

Teaching visuals

Craniocervical junction trauma — tension bands, ligaments & prevertebral soft tissueThe grave CCJ injury is often PURELY LIGAMENTOUS with NO fracture — clear it on ALIGNMENT and DISTANCES, not on bones.Lateral CCJ — sagittalanterior to the left · posterior to the rightAnteriortension bandPosteriortension bandBasionDens (odontoid)C2 bodyTectorial membraneTransverse ligamentAlarApicalBDIADIPrevertebralsoft tissueStabilizing ligamentstransverse + alar + tectorial = the main craniocervical stabilizersTectorial membranecranial PLL, runs behind the densTransverse ligamentdens to anterior C1 arch (cruciate)Alar ligamentsdens apex to occipital condylesApical ligamentdens tip to basionTension bands & the distances that clear or condemnAnterior band: bodies + ALL + disc + PLLPosterior band: flavum + interspinous /supraspinous + facet capsulesFail a tension band → instability. The CCJ leans onthese soft-tissue restraints, not on bony interlock.↑ Basion–dens interval (BDI)→ think atlanto-occipital dislocation (AOD)↑ Atlanto-dental interval (ADI)→ transverse-ligament disruption / atlanto-axial instabilityPrevertebral soft tissue (approximate)Upper / mid (≈C2–C3): roughly < 7 mm.Lower (≈C6): roughly < 22 mm (adult).Approximate adult rules of thumb — vary with age,positioning, phonation/crying (esp. children) &technique; confirm before quoting.Widening = red flag for occult injury, not a diagnosis.AOD + atlanto-axial dislocation travel together — find the other.Bottom line: No fracture does NOT clear the CCJ — the lethal injury can be purely ligamentous. Clear on alignment, distances & ligaments — then MRI + CTA.
CCJ Trauma — Tension Bands, Ligaments, Prevertebral Soft Tissue

Source lectures

  • Evaluation of CCJ Trauma

Educational material for radiology residents and neuroradiology fellows. Nothing here drives individual patient care, and it contains no patient data.