Carotid artery dissection: symptoms, diagnosis and treatment

The carotid arteries run up each side of the neck and supply most of the brain, the eyes and the face. In a dissection, blood gets into a tear in the inner lining and splits the layers of the wall, forming a bleed within the wall (an intramural haematoma) that can narrow or block the artery or allow clots to form and travel to the brain. A clinical article on imaging of carotid dissection says that, though rare at about 2.5 to 3 cases per 100,000 in the general population, it is diagnosed through awareness of its manifestations and advances in non-invasive imaging.

A study of endovascular treatment from a stroke centre notes that carotid dissection is a rare cause of ischaemic stroke but is responsible for 20% to 25% of strokes in young patients. Of 22 dissected arteries treated in that series, 12 patients lacked any history of trauma, which fits the clinical impression that many dissections are spontaneous, or follow only trivial strain.

The imaging article describes craniocervical dissection presenting in a variety of ways: headache and neck pain, an oculosympathetic palsy (Horner syndrome) and signs of cerebral ischaemia that may be delayed by hours or days. In the case it describes, a woman had two weeks of pressure and tightness on one side of the head, face and neck, a swishing sound in one ear, and then a red, droopy eyelid with a small pupil on the same side.

The Horner syndrome arises because the nerves that control the pupil and eyelid run along the artery in the skull base and are compressed when it swells. The article explains that enlargement of the dissected carotid in the non-distensible carotid canal results in this compression.

• Neck, face or head pain on one side, sometimes new and unlike previous headaches.

• A droopy eyelid and smaller pupil on the same side.

• A pulsing or swishing sound in one ear.

• Temporary or lasting loss of vision in one eye, or blurred vision.

• Face droop, arm weakness or speech disturbance, which are stroke signs.

The NHS describes the main symptoms of a stroke as face weakness, where one side of the face may droop, arm weakness and speech problems, summed up by the word FAST, with time to call 999. Other signs include weakness or numbness down one side, blurred vision or loss of sight in one or both eyes, difficulty finding words, confusion, dizziness or falling over, a severe headache and feeling or being sick.

The NHS says to call 999 now if you think you are having, or have had, a stroke, or if you have had signs of a stroke within the last 24 hours even if they have stopped, as symptoms can sometimes stop after a short time. It advises that you should not drive yourself to A&E. New severe neck or head pain with a drooping eyelid or visual change also needs urgent assessment, even without limb weakness.

The causes are often unclear. The sources we read indicate that dissection can follow injury, but that many cases have no history of trauma. The NHS lists general stroke risk factors including being over 50, Black or South Asian background, sickle cell disease, an unhealthy lifestyle, migraine, the combined contraceptive pill, pre-eclampsia in pregnancy and having just had a baby, and conditions such as high blood pressure, diabetes, atrial fibrillation and high cholesterol. These are general stroke factors rather than specific to dissection, and the sources we read do not give a list specific to carotid dissection.

If you have had a dissection with no obvious cause, ask your neurologist whether any tests for an underlying cause are appropriate.

The imaging article lists colour duplex ultrasonography, CT angiography, MRI and MR angiography, and conventional catheter angiography as the chief tests. They rely on seeing the wall abnormality, mainly an intramural haematoma, sometimes with an intimal tear. It reports that duplex ultrasound sensitivity ranges from 71% without symptoms of ischaemia to 95% when there is clinical cerebral ischaemia, and that MRI sensitivity and specificity are reported as 84% and 99%, respectively.

MRI and MR angiography of the head and neck can make the diagnosis and assess the brain supplied by the affected vessel, particularly in Horner syndrome. CT angiography provides better spatial resolution to assess a severely narrowed vessel. Dissection often begins beyond the origin of the vessel, unlike most atherosclerotic narrowing, and classically shows an eccentric contrast-filled lumen with a thickened crescent-shaped wall.

The imaging article states that treatment with anticoagulation therapy is usually sufficient and that dissections usually go on to heal, with decisions about reducing or stopping anticoagulation guided by follow-up MRI or CT angiography. It says surgical or endovascular treatment is rarely required. Recovery depends on the severity of the vascular compromise, with a mortality rate of up to 5%, and among patients with headaches a 90% symptom resolution rate is observed within a week.

The stroke centre study explains that conservative treatment is an option if ischaemic symptoms are mild and not progressing, while endovascular stenting or angioplasty was used in selected people with stroke, with 86.4% having good outcomes (modified Rankin score of 2 or less) but 18.2% developing symptomatic intracranial haemorrhage. It concludes prospective trials are needed. Which approach is right depends on your imaging, symptoms and a stroke specialist's judgement.

An acute presentation goes through 999 to hospital stroke services on the NHS. Follow-up is with stroke or neurology clinics, where repeat imaging is used to guide treatment, as the imaging article describes.

Private neurology or neuroradiology can offer quicker outpatient imaging, but anyone with possible dissection symptoms should not wait for a private appointment: go via 999 or NHS 111.