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Dural Arteriovenous Fistula

Summary

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  • Abnormal connection between dural arteries and venous sinuses or cortical veins
  • Presents with pulsatile tinnitus, headache, or intracranial haemorrhage
  • Diagnosed by catheter angiography; treated with endovascular embolisation or surgery

Pathophysiology

  • Acquired lesions resulting from:
    • Venous sinus thrombosis
    • Trauma
    • Surgery
    • Hypercoagulable states
  • Classified by Cognard or Borden systems based on venous drainage pattern
  • Increased risk of intracranial haemorrhage with cortical venous drainage

Demographics

  • Incidence: 0.15-0.29 per 100,000 person-years
  • Peak age: 50-60 years
  • Slight female predominance
  • Higher incidence in postmenopausal women and pregnancy

Diagnosis

  • Clinical presentation:
    • Pulsatile tinnitus
    • Headache
    • Intracranial haemorrhage
    • Seizures
    • Neurological deficits
  • Bruit on auscultation over mastoid or orbit
  • Catheter angiography: gold standard for diagnosis and classification

Imaging

  • CT:
    • Nonspecific findings
    • May show dilated vessels, venous sinus thrombosis, or haemorrhage
  • CT angiography:
    • Demonstrates abnormal arterial feeders and early venous filling
    • Limited in detecting small fistulas
  • MRI:
    • Flow voids representing enlarged vessels
    • T2 hyperintensity in white matter (venous congestion)
    • Susceptibility-weighted imaging: prominent cortical veins
  • MR angiography:
    • Time-of-flight and contrast-enhanced techniques
    • Shows abnormal arterial feeders and early venous filling
  • Catheter angiography:
    • Definitive diagnosis and classification
    • Identifies arterial feeders, fistula location, and venous drainage pattern

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  • A 60-year-old patient presented with headache.
  • An MRI on admission showed a dilated vessel in the posterior fossa with a rim of oedema within the cerebellum.
  • Immediately after the MRI, the patient's headache worsened and an CTA showed haemorrhage around the dural arteriovenous fistula that was supplied by the PICA.

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  • A 60-year-old patient presented with headache and ataxia.
  • The arterial phase of the DSA showed an abnormal vessel arising from the PICA draining into a dilated vein.

Treatment

  • Conservative management for low-risk fistulas (Cognard type I, IIa)
  • Endovascular embolisation:
    • First-line treatment for most cases
    • Transarterial or transvenous approach
    • Materials: coils, liquid embolic agents (Onyx, n-BCA)
  • Microsurgical resection:
    • Reserved for complex cases or endovascular failures
    • Direct exposure and disconnection of fistula
  • Stereotactic radiosurgery:
    • Adjunctive treatment or for small, surgically inaccessible fistulas
    • Delayed occlusion (1-3 years)
  • Follow-up imaging:
    • MRI/MRA or catheter angiography to assess treatment response and recurrence

Differential diagnosis

Differential Diagnosis Differentiating Feature
Arteriovenous Malformation Lacks direct arterial-venous shunting; has intervening nidus
Cavernous Malformation Lacks arterial feeders; characteristic "popcorn" appearance on MRI
Venous Angioma Single large draining vein; no arterial component
Capillary Telangiectasia Enhances on MRI but no flow voids; no arterial feeders
Pial Arteriovenous Fistula Located in brain parenchyma, not dural space
Tumour (e.g., meningioma) Solid mass effect; different enhancement pattern
Cerebral Aneurysm Focal dilatation of artery; lacks abnormal arteriovenous shunting
Moyamoya Disease Bilateral steno-occlusive changes; characteristic "puff of smoke" appearance
Sinus Thrombosis Filling defect in dural sinus; lacks arterial feeders
Sturge-Weber Syndrome Leptomeningeal angiomatosis; calcifications; usually in children