Cardiovascular

Carotid artery dissection

Blood enters the wall of a cervical carotid artery and forms an intramural haematoma whose raw surface embolises to the retina or brain, hours to days after the pain starts.

In a nutshell

Carotid artery dissection is a haematoma in the wall of a cervical carotid artery that embolises to the retina or brain. Image with CT or MR angiography, thrombolyse if otherwise eligible, then antiplatelet or anticoagulant treatment for at least 3 months.

Classic presentation

A woman in her forties develops left neck pain after minor whiplash, then a drooping left eyelid with a small pupil, and two days later right-sided weakness.

Key points

Horner syndrome here is partial: ptosis and miosis (a small pupil), with facial sweating preserved. A complete Horner syndrome points elsewhere along the sympathetic chain.
The local symptoms usually precede the ischaemic event by hours or days. That gap is the only chance to image and prevent the stroke.
Cerebral, retinal or spinal ischaemia complicates about two thirds to three quarters of published cases; more than one cervical artery is involved in 15% to 20%.
Carotid duplex cannot image the artery at the skull base. A normal duplex neither excludes dissection nor satisfies the guideline.
Subarachnoid haemorrhage is rare in cervical dissection and happens only when the tear extends into the intradural artery.
The artery recanalises in 33% to 90% of patients within 6 months, and dissecting aneurysms shrink or vanish in 40% to 50%.
Dissection is multifactorial in almost everyone. Fibromuscular dysplasia and inherited connective tissue disease are rare, so do not test every case.
Mean age is around 44 years, which is why dissection is a leading cause of ischaemic stroke in young adults.

First-line investigation

CT or MR angiography of the head and neck, preceded by non-enhanced CT brain whenever there is a neurological deficit.

Management

Recognise it and image it

Any acute focal deficit or sudden monocular visual loss is a stroke call. Non-enhanced CT brain immediately, aiming to image within 1 hour of arrival.^3,1
A new painful Horner syndrome (ptosis and a small pupil with sweating preserved) is a dissection until CT or MR angiography says otherwise.^1,2
Add CT angiography from aortic arch to skull vertex if thrombectomy might be indicated. Do not let it delay thrombolysis.^3,1

Reperfuse: dissection is not an exclusion

Alteplase 900 micrograms/kg intravenously, maximum 90 mg: 10% as a bolus, the rest over 60 minutes, within 4.5 hours of onset.^1,4,2
Tenecteplase is the single-bolus alternative: 15 mg below 60 kg rising to 25 mg at 90 kg or more, also within 4.5 hours.^5,1
Reduce blood pressure below 185/110 mmHg before thrombolysis.^1,3
Thrombectomy within 6 hours for a proximal anterior circulation occlusion, or from 6 to 24 hours if imaging shows salvageable tissue.^3,2
Both windows need a pre-stroke modified Rankin scale (independence before the stroke) below 3 and a National Institutes of Health Stroke Scale above 5.³

Antithrombotic: either arm, at least 3 months

Neither NICE nor the national guideline prefers antiplatelet or anticoagulant. Pick one and run it for at least 3 months after dissection-related ischaemic stroke or TIA.^3,1
Antiplatelet arm: aspirin 300 mg then 75 mg once daily plus clopidogrel 300 mg then 75 mg once daily for 21 days, then clopidogrel alone.^1,6,7
Anticoagulant arm: a direct oral anticoagulant (DOAC) or vitamin K antagonist for 3 months. Warfarin 5 to 10 mg on day 1, then 3 to 9 mg by INR.^1,8,2
No DOAC is licensed for dissection and the BNF gives no dose for it. Check the monograph and agree the choice with the stroke team.^9,10,1

The few who need more than drugs

Stenting is not routine, and evidence for treating residual stenosis or a dissecting aneurysm is too weak to recommend either way: neurovascular MDT.²
Intracranial dissection presenting with subarachnoid haemorrhage is the exception: early surgical or endovascular intervention.²

Reimage, then stop

Repeat CT or MR angiography in stroke clinic. Recanalisation occurs in 33% to 90% within 6 months; dissecting aneurysms shrink or resolve in 40% to 50%.²
Both trials stopped at 3 months, so no source supports treatment beyond it. Do not drift into indefinite antiplatelet therapy without another indication.^1,2
Investigate for fibromuscular dysplasia or an inherited connective tissue disorder only when dissections are bilateral, multiple, recurrent or syndromic.²

Exam traps

Dissection is not a contraindication to thrombolysis. If the patient is otherwise eligible, give alteplase 900 micrograms/kg (maximum 90 mg) within 4.5 hours.
There is no preferred antithrombotic: CADISS found no difference and TREAT-CAD did not show aspirin non-inferior to a vitamin K antagonist.
The 21-day aspirin and clopidogrel course after dissection is a separate recommendation from the 21-day course after transient ischaemic attack or minor stroke.
Evidence stops at 3 months. At least 3 months is not a licence to continue indefinitely, and no source gives a longer duration.
Do not stent a stable dissection. Evidence for treating residual stenosis or a dissecting aneurysm is too weak to recommend either way.
No direct oral anticoagulant (DOAC) is licensed for dissection, so the BNF gives no dose. The guideline permits one; the monograph will not say how much.
Someone already on a DOAC for a dissection who returns with a new stroke is excluded from thrombolysis, and reversing the DOAC to thrombolyse is not recommended.

Illustrations

Carotid artery dissection on ultrasoundLongitudinal carotid ultrasound showing an echogenic intimal flap separating true and false lumens, with a note that a normal ultrasound does not exclude a high cervical dissection.Mme Mim, Wikimedia Commons · CC-BY-SA-4.0

Partial Horner syndromeA clinical photograph showing subtle unilateral ptosis and miosis, with the teaching point that a painful partial Horner syndrome is an emergency until internal carotid dissection is excluded.Waster, Wikimedia Commons · CC-BY-2.5

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.