Dissection of the Carotid and Vertebral Arteries

Cervical artery dissection causes about 2% of all ischaemic strokes but 10 to 25% in patients under 50 years, making it a leading cause of stroke in young adults. Annual incidence is about 2.5 to 3 per 100,000 for internal carotid and 1 to 1.5 per 100,000 for vertebral dissection. Mean age is 45 to 50 years.

Pathophysiology

• An intimal tear allows blood to enter the arterial wall, forming an intramural haematoma.
• Subintimal haematoma causes luminal stenosis or occlusion and artery-to-artery embolism.
• Subadventitial haematoma creates a pseudoaneurysm and mass effect on adjacent nerves.
• Most strokes are embolic, not haemodynamic.

Predisposing factors

• Minor trauma: cervical manipulation, coughing, vomiting, sports, hyperextension.
• Connective tissue and vascular disorders: vascular Ehlers-Danlos syndrome, Marfan syndrome, fibromuscular dysplasia (in about 15 to 20%), ADPKD, osteogenesis imperfecta.
• Recent infection, migraine, hypertension, hyperhomocysteinaemia.

Anatomy

• Carotid dissection typically starts about 2 cm beyond the bifurcation, sparing the bulb, and may extend to the petrous segment.
• Vertebral dissection is commonest at V3 (C1 to C2 level). Intracranial V4 dissection can cause subarachnoid haemorrhage.

Recurrence is about 1% in the first month and about 0.3% per year thereafter.

Carotid dissection

• Unilateral head, face or neck pain in 60 to 90%.
• Partial Horner syndrome (ptosis and miosis with preserved facial sweating) in about half.
• Pulsatile tinnitus, taste disturbance, lower cranial neuropathies (CN IX to XII).
• Amaurosis fugax, TIA or hemispheric stroke.

Vertebral dissection

• Occipital or posterior neck pain.
• Vertigo, diplopia, ataxia, dysarthria, lateral medullary (Wallenberg) syndrome.
• C5 to C6 radiculopathy.
• Subarachnoid haemorrhage when intracranial.

Ischaemic events follow pain in most cases, within days and in about half within the first week. Isolated pain without ischaemia occurs in roughly 10%.

Red flags: new unusual headache or neck pain with Horner syndrome, recent trauma or manipulation, and stroke under 50 years with connective tissue stigmata. Differential diagnosis includes migraine, cluster headache, giant cell arteritis, subarachnoid haemorrhage and cervical radiculopathy.

CT angiography of head and neck is first-line, particularly in acute stroke, showing

• Eccentric tapered stenosis ("flame" or "rat-tail" taper).
• Occlusion.
• Pseudoaneurysm.
• Intimal flap or double lumen.
• Thickened vessel wall.

MRI with fat-suppressed axial T1 shows the hyperintense crescent of intramural haematoma, best seen after the first days, with a normal or reduced lumen. DWI identifies infarcts. MR angiography complements the study.

Other tests

• Duplex ultrasound is a screening tool only, with poor sensitivity for vertebral and distal carotid disease.
• Digital subtraction angiography is reserved for inconclusive cases or endovascular planning.
• Screen for an underlying arteriopathy with wider neck and cerebral vascular imaging for fibromuscular dysplasia, a family and skin history, hypermobility assessment, and COL3A1 genetic testing when vascular Ehlers-Danlos syndrome is suspected.
• Repeat imaging at 3 to 6 months. Most vertebral dissections and a majority of carotid dissections recanalise.

Acute ischaemic stroke

• IV thrombolysis within the treatment window is safe: alteplase 0.9 mg/kg (maximum 90 mg, 10% as bolus and the remainder over 60 minutes), or tenecteplase 0.25 mg/kg (maximum 25 mg). Avoid it when intracranial extension or subarachnoid haemorrhage is present.
• Endovascular thrombectomy for large vessel occlusion, including tandem lesions, with stenting of the dissected segment only when required.

Antithrombotic therapy to prevent embolism

• Antiplatelets and anticoagulation have similar efficacy. Either is started once haemorrhage is excluded.
• Antiplatelet option: aspirin 100 to 300 mg daily or clopidogrel 75 mg daily. For minor stroke or TIA, short-term dual therapy (aspirin 75 to 100 mg with clopidogrel 75 mg) for 21 to 90 days is an option.
• Anticoagulant option: IV unfractionated heparin without bolus aiming for aPTT 1.5 to 2 times control, or enoxaparin 1 mg/kg every 12 hours, bridging to warfarin INR 2 to 3. Direct oral anticoagulants such as apixaban 5 mg twice daily are used in practice.
• Avoid anticoagulation when there is intracranial extension, subarachnoid haemorrhage, or a large infarct at haemorrhagic risk. Use antiplatelets instead.
• Continue treatment for 3 to 6 months, then stop if the vessel has healed. Continue long-term antiplatelet therapy if a pseudoaneurysm persists, there are recurrent events or fibromuscular dysplasia is present.

Interventions

• Endovascular stenting is reserved for recurrent ischaemic events despite optimal medical therapy, contraindication to antithrombotics, or haemodynamic compromise.
• Surgical or endovascular treatment of enlarging pseudoaneurysms causing compression or embolism.

Supportive and preventive care

• Analgesia with paracetamol 1 g every 6 hours. Avoid triptans and ergots in the acute phase.
• Strict BP control, avoiding hypotension in occlusive disease.
• Avoid neck manipulation, heavy straining and contact sports for 3 to 6 months.
• Vascular Ehlers-Danlos syndrome: celiprolol starting at 100 mg daily and titrated up to 400 mg daily, and avoid invasive angiography where possible.
• Rehabilitation and smoking cessation. Follow-up imaging at 3 to 6 months.