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Dural Arteriovenous Malformations


Learning objectives

  • What is a Dural arteriovenous malformation/fistula
  • Role as a cause of ICH and SAH
  • Management of Dural arteriovenous malformation/fistula

Introduction

  • A Dural AV Fistula is a shunt from a dural artery (meningeal or occipital) to a dural venous channel
  • These are acquired deficits not congenital like AVMS and potential cause of ICH and SAH
  • 10 % of all intracranial AVMS. Most common in females > males

Aetiology

  • Causes include head injury, open surgery and Cerebral venous sinus thrombosis.
  • These "fistulae" are extra axial direct connections between arterial flow and dural venous sinuses.
  • The result is flow, shunting, pressure effects and venous congestion and haemorrhage.
  • They lie within the dura mater most commonly with the transverse sinus
  • Carotid-cavernous sinus shunts cause chemosis and scleral injection and an audible bruit.
  • Lesions without cortical venous reflex almost never cause neurological deficits

Sites

  • Cavernous sinus behind the eye: chemosis, reduced acuity, bruit, swelling of the eye.
  • Transverse/sigmoid sinus behind ear: pulsating noise (tinnitus). Stroke like symptoms, seizure like activity, headaches.
  • Vertebral artery

Classification

Clinical

  • Possibly asymptomatic, Dural pain fibres can lead to headache.
  • Seizures, bruits, headaches, stroke like episodes
  • Signs of increased intracranial pressure and bleeding.

Investigations

  • Diagnosis is by Angiography - CTA/MRA/DSA. There is usually localised venous congestion with dilated cortical veins and vasogenic oedema. Angiography demonstrated early venous filling with arterial supply from external carotid artery branches.

Management

  • Annual bleed risk is difficult to determine but felt to be less than 5% per annum.
  • Treatment options include conservative, endovascular embolisation using N-butyl-cyanoacryalate glue or other substance or surgery.
Last updated: 18/11/2018

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