Artery-to-artery embolic stroke

Related Subjects: |Acute Stroke Assessment (ROSIER&NIHSS) |Atrial Fibrillation |Atrial Myxoma |Causes of Stroke |Ischaemic Stroke |Cancer and Stroke |Cardioembolic stroke |CT Basics for Stroke |Endocarditis and Stroke |Haemorrhagic Stroke |Stroke Thrombolysis |Hyperacute Stroke Care

🧠 Introduction

An artery-to-artery embolic stroke occurs when thrombus or atheromatous debris from one arterial site dislodges ➝ occludes a downstream cerebral artery, causing ischaemia & infarction. ⚡ Unlike cardioembolic stroke, the embolus here originates from diseased arteries, most often in the neck or intracranial circulation. It accounts for a significant proportion of ischaemic strokes, particularly in patients with atherosclerosis or arterial dissection.

🔎 Etiology

• 🟢 Atherosclerotic plaque rupture: Most common; plaques at carotid bifurcation prone to thrombus & embolization.
• 🟢 Arterial dissection: Carotid/vertebral dissections expose intima → thrombus forms → emboli.
• 🟢 Aortic arch plaques: Complex plaques (>4 mm) highly emboligenic.
• 🟢 Other: Intracranial atherosclerosis, procedural vessel injury, inflammatory arteriopathies.

📍 Common Sources

• Extracranial carotid bifurcation: Classic site; bruit + amaurosis fugax clue 🚨
• Intracranial vessels (MCA, siphon): Common in Asian & Black populations.
• Arterial dissection: Neck pain, occipital headache, Horner’s syndrome.
• Aortic arch: High-risk plaques seen on TEE.

🩺 Clinical Features

• ⚡ Sudden onset: Maximal deficit at onset (similar to embolic pattern).
• 🧩 Territory-specific symptoms: MCA = hemiparesis/aphasia; PCA = hemianopia; vertebrobasilar = ataxia, diplopia.
• ⏳ TIAs: Preceding stroke due to intermittent embolization (warning sign).
• 👁 Amaurosis fugax: “Curtain coming down” over one eye (carotid emboli).
• 🦵 Vertebral dissection: Neck pain + lateral medullary features.

🧪 Investigations

• 🩸 Bloods: FBC, glucose, lipids, coagulation profile.
• 📉 ECG: Rule out AF (to distinguish from cardioembolic).
• 🖼 Brain imaging: CT (exclude bleed); MRI-DWI most sensitive for acute infarcts.
• 🫀 Vascular imaging:
  • Carotid Doppler (non-invasive, for stenosis).
  • CTA/MRA (visualise extracranial & intracranial vessels, dissections).
  • Cerebral angiography (gold standard, reserved for intervention).
• 🔊 Transcranial Doppler: Detects embolic signals in intracranial arteries.
• 🫁 Echocardiography: Rule out cardiac embolic sources if uncertain.

⚕️ Acute Management

• 💉 IV Thrombolysis (tPA): Within 4.5h of onset (if eligible).
• 🧩 Mechanical thrombectomy: Large vessel occlusions; effective up to 6h (sometimes extended with perfusion imaging).
• 💊 Antiplatelets: Aspirin 300 mg (unless thrombolysed → then post-24h).

🛡 Secondary Prevention

• 💊 Antiplatelets: Aspirin, clopidogrel, or dual therapy short-term in some cases.
• 💊 Statins: High-dose statin to stabilise plaques (LDL < 1.8 mmol/L target).
• ❤️ Risk factor control: BP, diabetes, smoking cessation, diet & exercise.
• 🔪 Carotid Endarterectomy (CEA):
  • Indicated if symptomatic & 70–99% stenosis.
  • Benefit greatest if performed within 2 weeks of TIA/stroke.
• 🪡 Carotid Stenting: Alternative in high surgical risk patients.
• 🩸 Arterial Dissection: Antithrombotic therapy (antiplatelet or anticoagulation) for 3–6 months; endovascular therapy if worsening.

📈 Prognosis

• 🟢 Better if treated early with thrombolysis or thrombectomy.
• 🟡 Risk of recurrence if stenosis untreated or risk factors uncontrolled.
• 🔴 Poor outcomes with large MCA/PCA occlusions or delayed recanalization.

📚 References

• Caplan LR. Artery-to-artery embolism: the neglected cerebral embolism. Arch Neurol. 1989.
• Brott TG et al. ASA/AHA Guidelines for extracranial carotid & vertebral artery disease. Stroke. 2011.
• Chimowitz MI et al. Warfarin vs aspirin for intracranial stenosis. NEJM. 2005.