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Dural arteriovenous fistulas, what they are, how they’re graded and treated in the UK.

An acquired shunt between dural arteries and venous sinuses. Most are treatable - and the presence of cortical venous reflux is the number that changes the plan.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Editorial team

    Written by our editorial team from the UK sources listed on each page.

  • 02

    Sourced from guidance

    Checked against national and specialist neurointerventional standards you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK practice for dAVF, including Cognard and Borden grading and endovascular first-line care.

Key facts

Dural arteriovenous fistulas at a glance.

The essentials, in plain English - what a dAVF is, where it sits and why grading changes everything.

  • What it is

    An acquired abnormal shunt between meningeal arteries and a dural venous sinus or cortical vein - not a true tangle of vessels like an AVM.

  • How common

    Around 10 to 15 per cent of intracranial vascular malformations - uncommon overall, most often diagnosed in adults aged 40 to 60.

  • What causes it

    Often idiopathic - but trauma, prior dural sinus thrombosis, previous cranial surgery or infection can trigger new shunts.

  • Where it sits

    Transverse-sigmoid sinus in about half of cases, then cavernous sinus, superior sagittal sinus, tentorial, anterior cranial fossa and spinal.

  • Why grading matters

    Cognard and Borden systems both hinge on cortical venous reflux - the single strongest predictor of bleeding.

  • First-line care

    Endovascular embolisation in a specialist neurointerventional centre, with microsurgery and radiosurgery reserved for selected cases.

Why this guide matters

A rare diagnosis with a specific playbook.

dAVF is uncommon enough to be missed in general clinics and specific enough to have a clear specialist pathway. The three points below shape everything else on this page.

  • Cortical venous reflux is the risk

    Fistulas that drain into cortical veins carry a real annual bleeding risk - which is why grading is central to every plan.

  • Angiography is still the gold standard

    MRI and CT angiography raise the question - digital subtraction angiography answers it and guides treatment.

  • Endovascular care is first-line

    Most dAVF are cured by a specialist neurointerventional procedure - surgery and radiosurgery play targeted roles.

How the diagnosis is made

From first symptom to a clear plan.

The steps a UK neurology, stroke or neurointerventional team will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and neurological exam

    Pulsatile tinnitus, red or protruding eye, new headache, seizure or focal deficit - the pattern points to the likely location.

  2. 02

    Assessing

    Baseline MRI and MRA

    Brain and, where symptoms suggest, spinal MRI look for flow voids, engorged pial veins, venous congestion oedema and cord signal change.

  3. 03

    Assessing

    CT angiography

    Adds bony detail around the skull base and sinuses and helps map arterial feeders before formal angiography.

  4. 04

    Confirming

    Digital subtraction angiography

    DSA is the gold standard - it maps every feeder, the venous drainage pattern and whether cortical venous reflux is present.

  5. 05

    Confirming

    Cognard and Borden grading

    The team classifies the shunt so risk of bleeding, seizure and progressive deficit can be weighed against treatment risk.

  6. 06

    Preparing

    Neurointerventional MDT

    A specialist team of interventional neuroradiology, neurosurgery and, for spinal cases, spinal surgery agrees the plan with you.

  7. 07

    Preparing

    Pre-treatment planning

    Anaesthetic review, imaging fusion and consent - including the specific risks of embolisation, microsurgery or radiosurgery.

Typical timeline: from first scan to specialist plan within weeks in a commissioned centre.

Symptoms

What a dAVF actually feels like.

A benign fistula without cortical venous reflux can be almost silent. An aggressive one can present as a stroke, seizure or rapidly worsening deficit.

  • Pulsatile tinnitus

    A whooshing sound in time with the heartbeat - classic for a transverse-sigmoid dAVF and often the first clue.

  • Red or protruding eye

    Proptosis, chemosis and painful eye movement point to a cavernous-sinus dAVF (see carotid-cavernous fistula).

  • Headache

    New, persistent or worsening headache - especially with venous hypertension features on imaging.

  • Seizures

    Focal or generalised seizures can be the first presentation when cortical venous reflux is present.

  • Intracranial haemorrhage

    A ruptured cortical vein or aneurysmal venous pouch causes subarachnoid or intraparenchymal bleeding - a medical emergency.

  • Focal neurological deficit

    Weakness, sensory change, visual loss or speech disturbance - from venous congestion or bleeding.

  • Cognitive decline or dementia

    Chronic venous hypertension can cause a reversible dementia picture - worth considering in atypical rapid cognitive decline.

  • Myelopathy (spinal dAVF)

    Progressive leg weakness, sensory level and bladder or bowel change - spinal dAVF is easily missed and treatable.

Treatment

How dural arteriovenous fistulas are treated in the UK.

Observation for the lowest-grade lesions, endovascular embolisation for most - with microsurgery and radiosurgery for selected cases.

  • Observation

    Low-grade Cognard I fistulas without cortical venous reflux can be watched, with imaging follow-up and symptom review.

  • Endovascular embolisation

    First-line for most dAVF - transarterial Onyx or nBCA and transvenous coiling by a specialist neurointerventional team (see /treatments/endovascular-embolisation/).

  • Microsurgical disconnection

    Selective open surgery to disconnect the cortical venous reflux - used for anterior cranial fossa, tentorial and some spinal fistulas.

  • Stereotactic radiosurgery

    Gamma Knife for surgically inaccessible or residual disease - takes months to work (see /treatments/gamma-knife-radiosurgery/).

  • Combined modality

    Embolisation followed by surgery or radiosurgery for complex fistulas where a single technique is unlikely to cure the shunt.

  • Spinal dAVF care

    Usually cured by targeted embolisation or a short open disconnection - early treatment protects the cord.

  • Rehabilitation

    Neuro-rehab supports recovery after haemorrhage, cognitive change or myelopathy (see /treatments/acquired-brain-injury-rehab/).

  • Symptom control

    Anti-seizure medication, headache management and eye care where relevant - alongside definitive treatment planning.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your neurologist or neurointerventional team knows your imaging and history and can tell you which parts apply to you. If in doubt, get seen.

  • British Society of Neuroradiologists. Standards for neurointerventional practice.

  • Society of British Neurological Surgeons. Guidance on cerebrovascular disease.

  • NHS England. Specialised neurosciences service specifications (adult neurosurgery and interventional neuroradiology).

  • European Stroke Organisation. Guideline on management of intracranial dural arteriovenous fistulas.

Red flags

When a dAVF needs urgent attention.

Some presentations are emergencies. These are the situations that shouldn’t wait - and where a neurointerventional opinion is needed fast.

  • Sudden thunderclap headache

    A ruptured dAVF can cause subarachnoid haemorrhage - call 999 for the worst headache of life.

  • New focal deficit

    Sudden weakness, speech disturbance or visual loss needs emergency assessment for haemorrhage or venous infarction.

  • First-ever seizure

    A new seizure in an adult always needs imaging - a dAVF is one of the vascular causes to consider.

  • Progressive leg weakness

    Ascending weakness, sensory level and bladder change suggest a spinal dAVF - urgent MRI of the whole cord.

  • Rapid cognitive decline

    A rapidly worsening dementia picture with venous hypertension imaging features is a dAVF until proven otherwise.

  • Painful red proptotic eye

    Suggests a cavernous-sinus fistula - needs urgent ophthalmology and neurointerventional review.

  • Cortical venous reflux

    Any Cognard IIb or higher grade fistula is a treat-not-watch situation - the annual bleeding risk is significant.

  • Pregnancy

    A known dAVF in pregnancy needs a joint plan with obstetrics, anaesthetics and neurointervention before delivery.

  • Anticoagulation

    Any new bleeding on anticoagulation with a known or suspected fistula is a neurosurgical emergency.

Living with it

A treatable diagnosis, with a clear pathway.

Four things that make the biggest difference after diagnosis - one specialist team, follow-up scans, prompt reporting of new symptoms, and time for rehab.

A quiet reminder

Continuity of team matters as much as the procedure.

A single centre keeping your imaging, grading and follow-up under one roof will spot a change earlier than a scattered set of appointments.

  1. 01 Team

    Stay under one specialist centre

    UK dAVF care sits in commissioned neurointerventional centres - keep your follow-up in one place so scans and grading stay consistent.

  2. 02 Imaging

    Turn up for follow-up scans

    Even a cured fistula deserves interval MRI and, at intervals, angiography - a small number recur or a new shunt develops elsewhere.

  3. 03 Symptoms

    Report new symptoms early

    New tinnitus, headache pattern change, eye symptoms or focal weakness after treatment always warrant an urgent call to your team.

  4. 04 Recovery

    Give rehab time

    After haemorrhage, seizure or myelopathy, structured neuro-rehab makes a measurable difference - it is a marathon, not a sprint.

Frequently asked

Everything we get asked about dAVF.

Quick answers on grading, angiography, embolisation and long-term follow-up.

  • What is a dural arteriovenous fistula?

    It is an acquired abnormal connection between arteries that supply the dura (the tough covering around the brain and spinal cord) and the veins or venous sinuses that drain it. Blood shortcuts through the fistula instead of following the normal capillary route, and that abnormal flow is what causes symptoms.

  • Is a dAVF the same as a brain AVM?

    No. A brain arteriovenous malformation (AVM) is a congenital tangle of vessels inside the brain tissue. A dAVF is an acquired shunt on the dural surface, without a nidus of abnormal vessels in the brain itself. They look and behave differently and are treated by the same specialist teams but with different techniques.

  • What causes a dAVF?

    Most are idiopathic - no clear trigger is found. Known triggers include previous dural venous sinus thrombosis, head injury, previous cranial surgery and, occasionally, infection. Once the fistula forms, venous hypertension and abnormal remodelling drive further change.

  • Why does cortical venous reflux matter so much?

    When a fistula drains into cortical veins on the brain surface, those thin-walled veins face arterial pressure they were never built for. That raises the risk of intracranial haemorrhage, seizures, focal deficit and progressive venous hypertension - which is why any fistula with cortical venous reflux is usually treated rather than watched.

  • How is a dAVF treated?

    Most dAVF are cured by endovascular embolisation - either through an artery using a liquid embolic like Onyx, or through a vein using coils. Some fistulas need selective microsurgical disconnection, and stereotactic radiosurgery is a good option when surgery is difficult and the risk of bleeding is not immediate. The right combination is agreed by a specialist neurointerventional MDT.

  • Can a dAVF come back after treatment?

    Yes, though most are curable in one or two procedures. A small proportion recur, and rarely a new shunt develops in a different location, particularly after prior sinus thrombosis. That is why long-term follow-up with MRI, and sometimes angiography, is part of standard care.

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