Dural Arteriovenous Malformations
Related Subjects:
|Acute Stroke Assessment (ROSIER&NIHSS)
|Causes of Stroke
|Ischaemic Stroke
|Cancer and Stroke
|Cardioembolic stroke
|CT Basics for Stroke
🧠 Introduction
- Dural Arteriovenous Fistula (dAVF) = abnormal shunt between a dural artery (meningeal/occipital) and a dural venous channel.
- Acquired (unlike congenital AVMs) ➝ can cause intracerebral haemorrhage (ICH) or subarachnoid haemorrhage (SAH).
- Account for ~10% of intracranial AVMs; more common in females.
⚙️ Aetiology
- Triggers: head trauma, previous cranial surgery, venous sinus thrombosis.
- Pathophysiology: direct arterial ➝ venous sinus connection ➝ high flow ➝ ↑ venous pressure ➝ venous congestion ➝ possible haemorrhage.
- Most often within the dura mater, especially the transverse sinus.
- Carotid–cavernous fistula: classically ➝ chemosis, scleral injection, pulsatile bruit.
- Without cortical venous reflux ➝ rarely cause neurological deficits.
📍 Common Sites & Presentations
- Cavernous sinus: 👁️ chemosis, proptosis, bruit, reduced vision.
- Transverse/sigmoid sinus: 👂 pulsatile tinnitus, headaches, seizures, stroke-like episodes.
- Vertebral artery/posterior fossa: 🌀 cerebellar or brainstem symptoms from venous congestion.
📑 Classification
💡 Prognosis depends on presence of cortical venous reflux → high risk of haemorrhage and neuro deficits.
🔎 Clinical Features
- May be asymptomatic or cause chronic headache (dural pain fibre irritation).
- Seizures, bruit, headaches, stroke-like events are common presentations.
- Raised ICP, ICH, or SAH ➝ in severe cases.
🧪 Investigations
- Gold standard = Digital Subtraction Angiography (DSA).
- CTA/MRA may show venous congestion, dilated cortical veins, vasogenic oedema.
- Key finding: early venous filling from external carotid artery branches.
💉 Management
- Annual bleed risk <5% (higher with cortical venous reflux).
- Options:
- 🟢 Conservative (stable, low-risk lesions).
- 🟡 Endovascular embolisation (N-butyl cyanoacrylate, Onyx).
- 🔴 Surgery (disconnection of fistula, venous sinus occlusion) if embolisation not feasible.
