Makindo Medical Notes

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.