Cervical spine injury

CT · MRI · X-ray

Draft this report · CT Draft this report · MRI Draft this report · X-ray

First and second year — the floor first, then every step

Thin-section CT from the occiput to the upper thoracic spine with sagittal and coronal reformats; the sagittal set is where alignment and the craniocervical junction are read.

Orient first

Stability is ligamentous as much as bony. A normal-looking vertebral body with a widened facet joint or interspinous space is a more dangerous injury than a crushed body with intact ligaments.
The craniocervical junction is where fatal injuries hide: atlanto-occipital dissociation and odontoid fractures can look subtle on axial slices and obvious on the sagittal reformat.
The cervicothoracic junction (C7 to the first thoracic vertebra) is the commonest level to be left unimaged; no study is complete without it.

Acquire the study

Thin (≤ 1 mm) bone-algorithm axial slices from the occiput to the second thoracic vertebra, with SAGITTAL and CORONAL reformats; read on bone AND soft-tissue windows.
Read sagittal reformats through the midline and through each facet column (left and right) — facet dislocation is seen on the parasagittal slices.
Extend to CTA of the neck when the fracture crosses a foramen transversarium, or there is subluxation — blunt cerebrovascular injury screening.

The manoeuvre

Craniocervical junction on the midline sagittal: basion–dens interval (BDI), the atlanto-dental interval (ADI; adult > 3 mm abnormal), and on the parasagittal slices the occipital condyle–C1 joint on each side.
Coronal: the C1 lateral masses over C2 — overhang of both sides suggests a Jefferson burst with transverse ligament injury; the odontoid base and body.
Alignment on the midline sagittal: anterior vertebral line, posterior vertebral line, spinolaminar line, and the tips of the spinous processes — each should be a smooth curve.
Parasagittal slices through each facet column: every facet joint should be congruent ("hamburger on a bun" on axial); perched, jumped or widened facets are the injury.
Each vertebra on axial bone window: body, pedicles, lamina, lateral mass, transverse process through the foramen transversarium, spinous process.
Prevertebral soft tissue on the soft-tissue window: at C2 it should be under about 7 mm and at C6 under about 22 mm in adults (verify local threshold) — swelling can be the only sign of a ligamentous injury.
Canal: retropulsed fragments, epidural haematoma, and the cord outline where visible.

What confirms it

A fracture line through cortex, OR loss of alignment / facet congruence / widened interspinous distance even without a fracture.

What licenses you to exclude it

A normal high-quality CT in an alert adult is used to clear the spine in most pathways; in an obtunded patient, CT clearance versus MRI is a local-protocol decision — state which applies.
A normal radiograph does not exclude injury if the cervicothoracic or craniocervical junction was not shown.

The classic misread

Reading only the midline sagittal and missing a unilateral facet dislocation seen on the parasagittal slices.
Missing an undisplaced odontoid base fracture parallel to the axial plane — check the coronal and sagittal.
Calling a normal-for-age pseudosubluxation of C2 on C3 in a child an injury — use the spinolaminar (Swischuk) line.

Reporting the injury

Classification to use

Subaxial (C3–C7): SLIC (Subaxial Injury Classification — morphology, disco-ligamentous complex, neurology) or AO Spine subaxial (A compression, B tension band, C translation) — state which.
Odontoid: Anderson–D'Alonzo I–III. C2 pars (hangman): Levine–Edwards. C1: Jefferson burst / arch fractures. Occipital condyle: Anderson–Montesano I–III.

Measurements — and how to take them

Translation (anterolisthesis) in mm or as a percentage of the vertebral body AP depth.
Atlanto-dental interval (adult > 3 mm abnormal); basion–dens interval (the CT upper limit is lower than the radiographic 12 mm; verify the threshold your department uses).
Canal AP diameter at the level of maximal compromise, in mm, and the percentage compromise against the levels above and below.
Kyphosis at the injured segment (Cobb angle, in degrees).

What to report

Level and every fractured element; alignment by line; facet status per side (perched, jumped, widened).
Craniocervical junction measurements when abnormal; prevertebral swelling.
Canal compromise, retropulsion, epidural haematoma; involvement of the foramen transversarium.
Any non-contiguous injury elsewhere in the spine.

How to report it

CT: "Bilateral C5/C6 facet dislocation (jumped facets) with 50% anterolisthesis of C5 on C6 and widening of the C5/C6 interspinous distance. The fracture of the right C6 lateral mass extends into the foramen transversarium; CT angiography recommended."
MRI: "High STIR signal throughout the C5/C6 interspinous ligament and ligamentum flavum with disruption of the posterior longitudinal ligament. Cord oedema extends from C4 to C6 without haemorrhage. Traumatic C5/C6 disc extrusion."

What not to report

Do not use "stable" or "unstable" as your only conclusion — describe the injured structures; stability is a clinical and surgical judgement that the report informs.
Do not report degenerative change at length in an acute trauma study; it buries the injury.

Associated injuries to look for

Vertebral artery injury (foramen transversarium fracture, subluxation), a non-contiguous second spinal fracture, head injury, and in ankylosing spondylitis or DISH a fracture through the fused spine that behaves like a long-bone fracture.

What changes management

Facet dislocation — traumatic disc herniation on MRI before closed reduction changes the approach.
Posterior ligamentous complex disruption, translation, or a fracture in an ankylosed spine.
Epidural haematoma or cord compression with deficit — emergency surgical communication.

Reference values

Each value carries the caveat that keeps it from being misused. Normal limits and diagnostic criteria are kept apart on purpose: a disease cut-off read as a normal range is the more dangerous mistake.

Normal limits

Cervical spine · atlantodental interval
up to 3 mm in adults, up to 5 mm in children
The paediatric limit is genuinely different — do not apply the adult figure to a child.
X-ray · CT
Craniocervical junction · Clivoaxial angle
roughly 150–180° in neutral position; progressively kyphotic angles below about 135° are associated with ventral brainstem compression
Sagittal midline image. The angle between a line along the posterior clivus and a line along the posterior margin of the odontoid and axis body.
⚠️ Published normal ranges genuinely vary and the angle changes with head position — treat trends and the flexion value as more informative than one neutral number.
CT · MRI
Occipitocervical junction (OC2) · Occiput–C2 angle
a named occipitocervical alignment angle; published means vary with the McGregor-versus-McRae baseline (those lines are already on the neuro shelf) — name the baseline
Lateral cervical / skull-base: the angle between a named foramen-magnum or hard-palate line (McGregor / McRae — already registered) and the C2 endplate or dens axis — state the pair.
Do not invent a single OC2 normal that ignores which skull-base line was used. Flexion–extension changes it.
X-ray · CT
Prevertebral soft tissues · thickness at C3 / at C6
up to 7 mm at C3, up to 22 mm at C6 in adults
Crying or a poorly-inspired film widens it in children; the C6 figure is smaller in children.
X-ray
Cervical spinal canal · Sagittal (AP) canal diameter, subaxial cervical spine
approximately 14–20 mm in adults; 10–13 mm is relative stenosis and under 10 mm absolute stenosis by the classic convention
Radiographic values are magnification-dependent — that is exactly what the Torg–Pavlov ratio was designed to escape, so on radiographs prefer the ratio and on CT/MRI measure directly. Functional (dynamic) narrowing in extension can exceed the static figure.
X-ray · CT · MRI
Atlanto-dental interval (child) · ADI in a child versus the adult entry
wider than the adult ADI convention — many texts accept up to about 5 mm in young children; the adult atlantodental entry must not be applied to a toddler
Lateral cervical radiograph or sagittal CT: distance between the posterior cortex of the anterior arch of C1 and the anterior cortex of the dens, in a true lateral.
Pseudosubluxation of C2 on C3 is another paediatric normal that an adult Swischuk-unaware read will over-call. The posterior cervical line (Swischuk) is the check.
X-ray · CT · paediatric

Diagnostic criteria

Cervical spine · Torg–Pavlov ratio
approximately 1.0; stenotic below about 0.8
Lateral cervical radiograph. The AP diameter of the spinal canal divided by the AP width of the corresponding vertebral body, at the same level.
⚠️ A RATIO EXISTS BECAUSE ABSOLUTE CANAL MEASUREMENT ON A RADIOGRAPH IS MAGNIFICATION-DEPENDENT — that is its whole purpose. It has a high false-positive rate in athletes with large vertebral bodies, so cross-sectional imaging governs any management decision.
X-ray
Craniocervical junction · Odontoid position against Chamberlain's line
the odontoid tip lies no more than about 3 mm above the line (some texts accept up to 5 mm)
Sagittal midline image. Chamberlain's line runs from the posterior margin of the hard palate to the opisthion (posterior lip of the foramen magnum).
⚠️ Texts genuinely differ between 3 and 5 mm — state which threshold is applied. On radiographs the opisthion is often invisible, which is why McGregor's line exists; on CT and MRI use the true bony landmarks.
X-ray · CT · MRI
Craniocervical junction · Odontoid position against McGregor's line
the odontoid tip lies no more than 4.5 mm above the line
Lateral radiograph or sagittal CT. McGregor's line runs from the posterior hard palate to the most caudal point of the occipital squama — usable when the opisthion cannot be seen.
The occipital landmark makes this the practical radiographic line, but it moves with skull-base anatomy — in doubt, cross-check with Chamberlain's line on CT.
X-ray · CT
Craniocervical junction · Odontoid position against McRae's line
the odontoid tip stays below the line; the line itself (foramen magnum AP diameter) measures approximately 35 mm
Sagittal midline image. McRae's line joins the basion to the opisthion — it is the anteroposterior diameter of the foramen magnum.
The most robust of the three classic lines because both landmarks are true bony margins of the foramen magnum. A dens above it means invagination whatever the other lines say.
X-ray · CT · MRI
Atlanto-occipital junction · Powers ratio (atlanto-occipital dissociation)under 1.0
Sagittal midline image. The distance from the basion to the posterior arch of C1, divided by the distance from the opisthion to the anterior arch of C1.
Insensitive to posterior and purely distractive dislocations — a normal ratio does not clear the joint. On CT the condyle–C1 interval and the basion–dens interval are the more sensitive measurements.
X-ray · CT
Atlanto-occipital junction · Basion–dens and basion–axial intervals
up to 12 mm each on the lateral radiograph (the "rule of twelves"); on CT the basion–dens interval is conventionally up to 8.5 mm in adults
Basion–dens interval: basion to the tip of the odontoid. Basion–axial interval: basion to a rostral extension of the posterior cortical line of the axis body (Harris method), on a true lateral or sagittal CT.
⚠️ THE RADIOGRAPHIC AND CT THRESHOLDS DIFFER — quoting the 12 mm radiographic figure on CT hides injuries the 8.5 mm criterion would catch. Paediatric craniocervical assessment uses different values again.
X-ray · CT
Paediatric cervical spine (Swischuk) · Swischuk posterior cervical line
a line along the anterior cortex of the C1 and C3 spinous processes should pass within about 1–2 mm of the anterior C2 spinous process; a larger step is the true C2–C3 injury conversation, not physiologic pseudosubluxation
True lateral cervical radiograph: the Swischuk line joins the anterior cortices of the C1 and C3 spinous processes and is judged against C2.
Pseudosubluxation is common under about 8 years. A broken Swischuk line is not physiology.
X-ray · paediatric

See it on real cases

Direct links to Radiopaedia — the reference article and worked cases with their images. Each opens on Radiopaedia.

Key papers

Reviews and guidelines from RSNA, ESR and related journals. Each opens at its DOI.

Multidetector CT of blunt cervical spine trauma in adults ↗Dreizin D, Letzing M, Sliker CW, et al. · RadioGraphics 2014RSNA · PubMed
Imaging evaluation of adult spinal injuries: emphasis on multidetector CT in cervical spine trauma ↗Munera F, Rivas LA, Nunez DB Jr, et al. · Radiology 2012RSNA · PubMed
Utility of MRI for cervical spine clearance after blunt traumatic injury: a meta-analysis ↗Malhotra A, Wu X, Kalra VB, et al. · European Radiology 2017ESR · PubMed
Emergent Imaging of Pediatric Cervical Spine Trauma ↗McAllister AS, Nagaraj U, Radhakrishnan R · RadioGraphics 2019RSNA · PubMed