Arteriovenous Malformations
AVMs: At a Glance
What it is: A brain arteriovenous malformation (AVM) is an abnormal tangle of blood vessels connecting arteries and veins in the brain.
How it affects people: Some AVMs cause no symptoms, but can cause neurological problems, seizures or serious bleeding (which can cause headaches).
Key concern: The risk of rupture, causing an intracranial haemorrhage and brain damage.
Diagnosis: Usually identified with imaging tests such as MRI, CT, or cerebral angiography.
Treatment options: Monitoring, sterotactic radiosurgery, endovascular techniques, or surgery depending on the AVM’s size, location, and risk of bleeding.
Outlook: With expert care, many AVMs can be safely monitored or treated, reducing the risk of complications in the long term.
What is an AVM?
An AVM is an abnormal connection between arteries and veins in the brain. Instead of flowing smoothly through tiny capillaries, blood passes directly from arteries to veins. This can increase pressure in the vessels and sometimes cause them to rupture, leading to bleeding in the brain.
AVMs affect the central nervous system, most commonly in the brain but sometimes in the spinal cord. Not all AVMs cause symptoms, and many are discovered incidentally during scans for other conditions.
Types of AVMs
AVMs are most often found in the brain but can also occur in the spinal cord. Types include:
Brain AVM: The most common form, affecting the arteries and veins inside the brain.
Spinal vascular malformations: These include spinal AVMs (within the spinal cord itself) and spinal dural arteriovenous fistulae (dAVF), where the abnormal connection is in the covering of the spinal cord.
AVM Symptoms
Common symptoms (unruptured AVM)
Most unruptured AVMs cause no symptoms and are discovered incidentally on scans done for other reasons. When symptoms do occur, they may include:
Seizures
Weakness or numbness in part of the body, vision problems and/or difficulty speaking
Emergency / red flag symptoms (ruptured AVM)
Sudden, severe headache
Nausea and vomiting
Seizures
Loss of consciousness
Sudden weakness or paralysis
Seek urgent medical attention or call 999 if you experience these symptoms.
Causes and Who Is at Risk
The cause of AVMs is not fully understood. Most are thought to be present from birth (a medical condition that is congenital) or develop early in childhood, though they are not usually inherited in families.
Health and Family Factors You Can’t Change
AVMs are slightly more common in men.
They are usually diagnosed in young adults but can be found at any age.
Rarely, AVMs may occur as part of other vascular malformations or inherited syndromes, such as hereditary haemorrhagic telangiectasia.
Having a risk factor does not mean you will definitely develop an AVM.
Reducing Your Risk
Because most AVMs are congenital, they cannot usually be prevented. However, you can reduce the risk of complications by:
Controlling high blood pressure
Avoiding smoking and heavy drinking
Having regular follow-up scans if you have been diagnosed with an AVM
Getting a Diagnosis
An AVM is usually diagnosed through specialist imaging tests, such as:
MRI scan: Provides detailed images of brain structure and blood flow.
CT scan: Can detect bleeding from a ruptured AVM.
Cerebral angiogram: A precise test using dye and X-ray to map blood vessels in the part of the brain.
These tests are highly accurate and allow a neurosurgeon or neurovascular surgeon to recommend the safest treatment option.
Treatment Options for AVMs
Treatment for AVM depends on the size, type, and location, as well as the patient’s overall health. Options may include:
Monitoring
In some cases, monitoring and symptom management may be the safest approach
Endovascular Embolisation
A procedure performed by an interventional neuroradiologist, in which a catheter delivers material to block abnormal blood flow.
Surgery
In some cases, the AVM may be removed through open cranial surgery (microsurgical resection).
Stereotactic Radiosurgery
A focused form of radiotherapy sometimes used to shrink or close off small AVMs in difficult locations.
Every patient’s case is carefully reviewed in collaboration with neuroradiology colleagues to ensure the best possible outcome. Mr Kailaya-Vasan, Consultant Neurosurgeon, specialises in neurovascular surgery and minimal access brain surgery, providing expert care for patients in London, across the UK, and internationally.
Living with an AVM
Many AVMs never rupture and can be managed safely with monitoring. When treatment is needed, modern techniques mean most patients recover well and can return to normal activities.
With early diagnosis and the right specialist care, outcomes are greatly improved. Under the care of a consultant neurosurgeon like Mr Kailaya-Vasan, treatment is carefully tailored to each patient, with a focus on safety, precision, and long-term wellbeing.
Book a consultation with Mr Ahilan Kailaya-Vasan
Receive a clear diagnosis and a tailored treatment plan from a leading consultant neurosurgeon. Appointments are available at top London hospitals, with remote options for international patients.
Seeking a second opinion?
If you have already received a diagnosis elsewhere, Mr Kailaya-Vasan can provide an independent review of your scans and medical notes, and explain the safest and most effective next steps.
FAQs about AVMs
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Most AVMs are not inherited, although in rare cases they may occur with genetic conditions such as hereditary haemorrhagic telangiectasia.
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No, AVMs cannot be prevented as most are congenital. However, controlling blood pressure and avoiding smoking and heavy drinking may reduce the risk of complications.
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Recovery depends on the type of treatment and whether the arteriovenous malformation (AVM) has ruptured. Patients treated for an unruptured AVM often return to normal life within weeks. If the AVM has ruptured, recovery may take longer and rehabilitation is often needed. Close follow-up helps to achieve the best outcomes and manage any side effects of treatment.
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No. Many AVMs may be safely monitored. Treatment is usually recommended if there is a higher risk of bleeding or if symptoms are causing problems.
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Seek emergency medical attention or call 999 if you experience a sudden, severe headache, seizures, or sudden neurological changes such as weakness, vision problems, or speech difficulties.
If you have any further questions, please get in touch.