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Health condition · Clinically reviewed

CNS vascular malformations, AVM, cavernoma, DVA, dAVF, vein of Galen and spinal lesions.

Six different lesions, one specialist pathway. A plain-English guide to how brain and spine vascular malformations are diagnosed and treated in the UK.

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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

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BNSS, BSNR and peer-reviewed neurovascular sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK neurovascular practice including Gamma Knife, endovascular embolisation and genetic testing.

Key facts

CNS vascular malformations at a glance.

The six main types, the imaging that identifies them and the genetic conditions that group them into families.

  • What it is

    A family of abnormal blood vessels in the brain or spinal cord. Six main types, each with its own risk profile and treatment path.

  • AVM

    Arteriovenous malformation. Arteries feed directly into veins with no capillary bed. Graded Spetzler-Martin I to V.

  • Cavernoma

    Cavernous malformation. A raspberry-like cluster of dilated capillaries. Annual haemorrhage risk of around 0.5 to 1.5 per cent.

  • DVA

    Developmental venous anomaly. Usually incidental, benign and a normal drainage variant. Not to be resected.

  • dAVF

    Dural arteriovenous fistula. Pulsatile tinnitus and haemorrhage risk when cortical veins drain the shunt.

  • Genetics

    CCM1, CCM2, CCM3 for familial cavernoma. ENG and ACVRL1 for HHT. RASA1 for CM-AVM. PIK3CA for related overgrowth.

Why this guide matters

Different lesions, different plans.

The name of the lesion matters. Treatment for a DVA is not treatment for an AVM. Getting the diagnosis right is the whole game.

  • Not all lesions need treatment

    DVAs and capillary telangiectasias are usually benign incidental findings. Resecting a DVA can cause a venous infarct.

  • MRI first, angiography if needed

    MRI with MRA and SWI characterises most lesions. DSA is reserved for AVM and dAVF where treatment planning requires it.

  • A neurovascular MDT is essential

    Complex AVM, dAVF, spinal and paediatric cases belong at specialist centres with combined neurosurgery, interventional neuroradiology and radiosurgery on hand.

How the diagnosis is made

From first symptom to a specialist plan.

The steps a UK neurologist, neurosurgeon or interventional neuroradiologist will normally follow.

  1. 01

    Assessing

    History and neurological exam

    Headache, seizure, focal deficit, pulsatile tinnitus or an incidental scan finding. A careful exam sets the direction.

  2. 02

    Assessing

    MRI with MRA and SWI

    First-line imaging. Characterises the lesion type and picks up old haemosiderin on susceptibility-weighted sequences.

  3. 03

    Assessing

    CT and CTA if acute

    For sudden severe headache, suspected haemorrhage or emergency planning. Fast and widely available.

  4. 04

    Confirming

    Digital subtraction angiography

    DSA is the gold standard for AVM and dAVF. Maps feeders, drainage and haemodynamics for treatment planning.

  5. 05

    Confirming

    Neurovascular MDT review

    Every complex case is discussed at a specialist centre by neurosurgery, interventional neuroradiology and radiation oncology.

  6. 06

    Family

    Genetic testing where indicated

    CCM1, CCM2, CCM3 for familial cavernoma. HHT gene panel for suspected hereditary haemorrhagic telangiectasia. RASA1 for CM-AVM.

  7. 07

    Family

    Family screening and HHT workup

    Cascade testing for relatives. Contrast echo, CT chest and hepatic imaging where HHT is suspected. EEG for seizures.

Typical timeline: urgent for haemorrhage, planned for incidental findings.

Symptoms

How these lesions declare themselves.

From an incidental scan finding to a life-changing bleed, the presentation depends on the lesion type and its location.

  • Incidental finding

    Many DVAs, capillary telangiectasias and small cavernomas are picked up on scans done for another reason.

  • Headache

    Sudden severe headache raises concern for haemorrhage. Chronic headache alone is rarely due to a vascular malformation.

  • Seizure

    A common presentation of cortical cavernoma and AVM. Requires EEG and antiepileptic medication.

  • Focal neurological deficit

    Weakness, numbness, speech or vision change. Reflects the location of the lesion or a bleed.

  • Intracerebral or subarachnoid haemorrhage

    The feared complication of AVM, cavernoma and high-risk dAVF. An emergency needing neurosurgical assessment.

  • Pulsatile tinnitus

    A whooshing sound in time with the pulse is a classic dAVF symptom, especially near the transverse or sigmoid sinus.

  • Neonatal high-output cardiac failure

    The presentation of vein of Galen malformation. Needs urgent transfer to a specialist paediatric neurovascular centre.

  • Red flag - thunderclap headache

    Sudden worst-ever headache with vomiting or reduced consciousness is a 999 emergency.

Treatment

How these lesions are treated in the UK.

Observation, microsurgery, radiosurgery, embolisation or a combination. Chosen at a neurovascular MDT and matched to the lesion.

  • Observation

    Small, incidental and low-risk lesions - DVA, capillary telangiectasia, some cavernomas - are watched with interval MRI rather than treated.

  • Microsurgical resection

    Open neurosurgery for accessible AVM, symptomatic cavernoma or high-grade dAVF. Curative when complete.

  • Stereotactic radiosurgery

    Gamma Knife or CyberKnife for AVM and select cavernomas. Vessels obliterate over two to three years with millimetre precision.

  • Endovascular embolisation

    Catheter delivery of Onyx or coils to occlude AVM feeders, dAVF shunts or vein of Galen malformations. Often staged.

  • Combined multimodal treatment

    Complex AVMs may need embolisation to shrink the nidus, then surgery or radiosurgery. Planned at neurovascular MDT.

  • Antiepileptic medication

    For seizure control before, during and after definitive treatment. Adjusted to the lesion location and patient factors.

  • Blood pressure control

    Tight BP management reduces rebleeding risk and is essential after any haemorrhagic event.

  • Neurorehabilitation

    After a bleed or surgery - physiotherapy, occupational therapy, speech and language therapy and neuropsychology.

What this guide is based on

The sources behind every claim on this page.

UK national guidance, specialist society standards and patient charities, 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, neurosurgeon or interventional neuroradiologist knows your scans and history. If in doubt, ask them.

  • NICE. Suspected neurological conditions: recognition and referral (NG127).

  • British Society of Neuroradiologists (BSNR). Guidance on cerebral angiography and neurointervention.

  • Society of British Neurological Surgeons (SBNS). Standards for neurovascular surgery.

  • Cavernoma Alliance UK. Patient information on cerebral cavernous malformations.

  • HHT UK. Hereditary haemorrhagic telangiectasia diagnosis and screening.

Red flags

When to act, and act fast.

Most vascular malformations are managed calmly over weeks. These situations are not - they need immediate attention.

  • Thunderclap headache

    Sudden worst-ever headache with vomiting, neck stiffness or reduced consciousness is a 999 emergency for suspected subarachnoid haemorrhage.

  • New focal deficit

    Sudden weakness, numbness, speech loss or visual change needs immediate hyperacute stroke assessment.

  • First seizure

    A first-ever seizure warrants an urgent brain scan and neurology review to look for a structural cause.

  • Neonatal heart failure with head bruit

    A neonate in high-output cardiac failure with a cranial bruit needs urgent transfer for suspected vein of Galen malformation.

  • Pulsatile tinnitus with bruit

    Pulsatile tinnitus, especially with an audible bruit, should be investigated for dAVF - not dismissed as benign.

  • Rapidly progressive myelopathy

    Progressive leg weakness, sensory level and bladder change may indicate a spinal dAVF - an imaging emergency.

  • Known cavernoma with recurrent bleeds

    Two or more symptomatic haemorrhages from the same lesion is an accepted indication for surgical resection.

  • Family history of stroke in the young

    A family history of unexplained young stroke or multiple cavernomas warrants genetic counselling.

  • HHT with cerebral symptoms

    Any neurological symptom in a person with HHT needs brain and spine MRI to look for AVM and telangiectasia.

Living with it

A long game, with the right team.

Whether the plan is observation or an intervention, four things make the biggest difference year to year.

A quiet reminder

A named specialist team is worth the referral.

Ask which neurovascular MDT is looking after you and how to contact them between appointments.

  1. 01 Observation

    Interval MRI is a plan

    Watching a stable, low-risk lesion with scheduled scans is active management, not neglect. Turn up to every appointment.

  2. 02 Lifestyle

    Blood pressure and lifestyle

    Keep BP well controlled, avoid smoking and drink within limits. These are the modifiable levers for haemorrhage risk.

  3. 03 Support

    Charities exist for a reason

    Cavernoma Alliance UK, HHT UK and the Brain and Spine Foundation offer information, peer support and second opinions.

  4. 04 Family

    Genetics is a family conversation

    If a hereditary syndrome is confirmed, cascade testing and reproductive counselling are open to relatives who want them.

Frequently asked

Everything we get asked about CNS vascular malformations.

Quick answers on AVM, cavernoma, DVA, dAVF, vein of Galen and spinal lesions.

  • What is a CNS vascular malformation?

    It is an umbrella term for abnormal blood vessels in the brain or spinal cord. The main types are AVM, cavernoma, developmental venous anomaly, capillary telangiectasia, dural arteriovenous fistula and vein of Galen malformation. Each has a different risk profile and treatment path.

  • Do all vascular malformations need treatment?

    No. Developmental venous anomalies and most capillary telangiectasias are benign, incidental and left alone. Small unruptured cavernomas and low-grade AVMs are often watched. Symptomatic or high-risk lesions are treated by a specialist neurovascular team.

  • What is the risk of bleeding from a cavernoma?

    The annual haemorrhage risk is around 0.5 to 1.5 per cent for an unruptured lesion, and higher after a first bleed or in the brainstem. Familial cavernomatosis and CCM3 mutations carry a higher lifetime risk.

  • What treatments are used for an AVM?

    Microsurgical resection, stereotactic radiosurgery with Gamma Knife or CyberKnife, and endovascular embolisation with Onyx. Complex AVMs often need a combination, planned at a neurovascular MDT.

  • Where are these treated in the UK?

    Specialist neurovascular centres including Queen Square, King's, Cambridge, Oxford, Newcastle, Sheffield, Manchester, Bristol, Leeds, Edinburgh and Glasgow. Neonatal vein of Galen work is centred on Great Ormond Street, Alder Hey and Bristol.

  • Is genetic testing offered?

    Yes, where the clinical picture suggests a familial syndrome. Panels include CCM1, CCM2 and CCM3 for familial cavernoma, ENG and ACVRL1 for HHT and RASA1 for CM-AVM. NHS Genomic Medicine Services coordinate testing and cascade screening.

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