First and second year — the floor first, then every step
CTA of the neck in a screened patient: follow each carotid and vertebral artery from origin to skull base and grade what you find by the Biffl (Denver) scale — the grade decides antithrombotic therapy or intervention.
Orient first
Blunt carotid and vertebral injuries are dissections, pseudoaneurysms, occlusions or transections caused by stretch or by fracture fragments; many are asymptomatic when found and cause stroke hours to days later.
The high-risk sites follow the bones: the vertebral artery in the foramen transversarium (with a cervical fracture through it), the distal cervical internal carotid against C1–C2, and the petrous carotid in a skull-base fracture.
Screening criteria (expanded Denver and similar) select who gets imaged; you should know them because the fracture you report may be the trigger.
Acquire the study
CTA from the aortic arch to the vertex, arterial phase, thin slices (≤ 1 mm) with multiplanar and curved reformats along each vessel.
Read each of the four arteries separately, in axial and along the vessel on curved reformats; compare the calibre with the contralateral side.
When CTA is equivocal, MRI with fat-suppressed T1 through the neck is the study that shows intramural haematoma (a crescent of high signal).
The manoeuvre
Follow each internal carotid artery from the bifurcation to the cavernous segment, and each vertebral artery from its origin through every foramen transversarium to the basilar.
Look for luminal irregularity, an intimal flap, eccentric narrowing with a crescent of mural thickening, a focal outpouching (pseudoaneurysm), abrupt tapering (flame-shaped occlusion) and contrast outside the vessel.
Estimate the degree of luminal narrowing against the normal lumen distal to the lesion.
Cross-check the spine: a fracture through a foramen transversarium, subluxation or facet dislocation raises the prior for the vertebral artery at that level.
Look at the brain for established infarction in the relevant territory.
What confirms it
An intimal flap or intramural haematoma with luminal narrowing on two planes is a dissection; a contrast-filled outpouching beyond the expected lumen that persists on all reformats is a pseudoaneurysm.
What licenses you to exclude it
A good-quality CTA is the accepted screening test; a study degraded by streak artefact at the skull base or by poor opacification does not exclude a low-grade injury — say which segments were not assessable.
The classic misread
Mistaking a hypoplastic vertebral artery for occlusion — a hypoplastic artery is small throughout and ends in PICA or joins normally.
Mistaking streak artefact from dental work or the skull base for an intimal flap — confirm on another plane.
Calling the tapered vessel of a dissection "atherosclerotic" in a young trauma patient.
Reporting the injury
Classification to use
Biffl (Denver) grading: I — luminal irregularity or dissection with < 25% narrowing; II — dissection or intramural haematoma with ≥ 25% narrowing, intraluminal thrombus or raised intimal flap; III — pseudoaneurysm; IV — occlusion; V — transection with free extravasation.
Measurements — and how to take them
Percentage luminal narrowing (the Biffl threshold between grades I and II is 25%).
Pseudoaneurysm neck and maximal diameter in mm.
What to report
Which artery, which segment (e.g. V2 at C4 in the foramen transversarium; cervical ICA at C1–C2), the grade, and the percentage narrowing.
Any intraluminal thrombus, the fracture that relates to it, and any infarct in the territory.
Segments not assessable, and why.
How to report it
CT: "Right cervical internal carotid artery dissection at the level of C2 with approximately 40% luminal narrowing and a raised intimal flap — Biffl grade II blunt cerebrovascular injury. No infarct."
CT: "Occlusion of the left vertebral artery in V2 from C5 to C3, adjacent to a fracture through the left C5 foramen transversarium — Biffl grade IV."
What not to report
Do not describe a finding only as "irregularity" without grading it; the grade is what starts treatment.
Do not call a hypoplastic vertebral artery an occlusion.
Associated injuries to look for
Cervical spine fractures through the foramen transversarium or with subluxation, skull-base fractures through the carotid canal, Le Fort II/III fractures, and diffuse axonal injury.
What changes management
Grades I–IV: antithrombotic therapy is usual, balanced against the bleeding risk of the other injuries — this is the conversation the report must trigger.
Grade III: follow-up imaging and consideration of endovascular treatment; grade V: emergency intervention.
A follow-up CTA interval (often 7–10 days) is common to re-grade — verify local protocol.
See it on real cases
Direct links to Radiopaedia — the reference article and worked cases with their images. Each opens on Radiopaedia.