Skull-base fracture involving the carotid canal — MRCEM SBA MCQ

Correct answer: B — CT angiography of the neck vessels

The fracture extends through the carotid canal, so its course raises suspicion of internal carotid artery injury. An alert patient can have a vascular injury without a focal deficit, and a non-contrast CT head showing no haemorrhage does not assess the artery. NICE recommends CT or MRI angiography of the neck vessels when a high-risk skull-base fracture is likely to involve the internal carotid or vertebral artery. CT angiography of the neck vessels is therefore the appropriate next investigation; the normal cervical spine CT does not remove the concern created by the skull-base fracture. ([nice.org.uk](https://www.nice.org.uk/guidance/NG232/chapter/recommendations)) A is a tempting arterial study, but limiting it to intracranial vessels would not provide the recommended neck-vessel assessment. C would investigate suspected venous sinus injury rather than the arterial risk indicated by a carotid-canal fracture. D can characterise carotid pathology, but it is not the best initial investigation when the indicated non-invasive angiographic study has not yet been performed. E may help evaluate brain or brainstem pathology, but conventional MRI does not replace angiography for this suspected vascular injury. The imaging decision is driven by the fracture’s anatomical course, not by the absence of current neurological signs.

Reference: NICE NG232: Head injury—assessment and early management, recommendation 1.6.10 (2023 amendment) — https://www.nice.org.uk/guidance/NG232/chapter/recommendations