What Are Intracranial Venous Malformations? The Brain Veins Most People Never Need to Treat
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer
An intracranial venous malformation is an unusually large vein in the brain that usually still works normally. Most cause no symptoms and are found by accident during brain imaging, though some cause headaches, seizures or dizziness. CT, MRI, MRA and MRV diagnose it. It usually needs no treatment, and medicines can help symptoms such as headaches or seizures. [1] [2]
What the research says
Bleeding is mostly linked to associated malformations. A systematic review of 9 studies on developmental venous anomalies (the term doctors also use) that coexist with a dural arteriovenous fistula found that most patients presented with bleeding (56%), and that the fistula was the treatment target in every case, with 78% completely occluded. The authors note that venous anomalies with arteriovenous shunts seem to have a worse clinical picture than isolated ones. (Agosti et al., Front Surg, 2023)
Most are benign and only uncommonly symptomatic. A state-of-the-art review describes developmental venous anomalies as the most common slow-flow venous malformation in the brain, notes that most are benign and that uncommonly they become symptomatic, and advises a systematic imaging approach when they do. (Hsu and Krings, AJNR Am J Neuroradiol, 2023)
What is an intracranial venous malformation?
An intracranial venous malformation is a vein in the brain that is unusually large. "Intracranial" simply means inside the skull. These larger veins are not likely to cause symptoms or affect how the veins work. They carry blood as veins normally do, just with a bigger size than usual. [1]
Some people have an intracranial venous malformation that is never diagnosed and never causes symptoms. Sometimes they are found by accident during a brain imaging test for another condition, and they usually do not require treatment. [1]
What are the symptoms?
Intracranial venous malformations may never cause symptoms. If one does, symptoms may include the following. [1]
Possible symptom | What you might notice |
|---|---|
Headaches | Pain in the head that may be new or unusual for you |
Seizures | Sudden episodes of abnormal brain activity |
Dizziness | Feeling unsteady, lightheaded or off balance |
Nausea and vomiting | Feeling sick to your stomach, sometimes with vomiting |
Muscle weakness or paralysis | Reduced strength in a muscle or an inability to move it |
Loss of coordination | Difficulty moving smoothly or keeping your balance |
Vision troubles | Problems with eyesight |
Difficulty speaking | Trouble finding words or getting them out clearly |
Memory problems | Difficulty remembering things you could before |
These symptoms overlap with many far more common conditions, so they do not point to a venous malformation on their own, and only imaging tests can show one. Seek medical attention if you have any of these symptoms, not because they most likely point to this condition, but because they deserve an explanation. [1]
What causes intracranial venous malformations?
Experts do not understand what causes them. Certain genetic changes might play a role, and the malformations may form during fetal development, before birth. Some types are not inherited at all and are acquired later in life, possibly after an injury to the central nervous system (the brain and spinal cord). [1]
Having a family history of intracranial venous malformations can increase your risk, but most types are not inherited. Certain hereditary conditions that affect blood vessels can also increase the risk. [1]
Hereditary condition | What it involves |
|---|---|
Hereditary hemorrhagic telangiectasia | A condition that affects blood vessels and can cause abnormal vessel formation |
Sturge-Weber syndrome | A condition that affects the skin and the blood vessels of the brain |
Klippel-Trenaunay syndrome | A condition that affects blood vessels, skin and soft tissues |
Most intracranial venous malformations appear in people with none of these risk factors.
How are intracranial venous malformations diagnosed?
Because you may not have symptoms, your healthcare team might find the condition during testing for other neurological problems. Imaging tests that can show it include: [2]
Imaging test | What it does |
|---|---|
CT scan | A series of X-rays creates detailed cross-sectional images of the blood vessels and the brain. Dye is sometimes injected into a vein for greater detail, which is called a CT angiogram or CT venogram |
MRI | Magnetic and radio waves create detailed 3D images of your blood vessels and brain. A contrast dye is sometimes injected to look at the brain tissue differently and evaluate the blood vessels |
MRA | Magnetic resonance angiography is an MRI that focuses on the arteries and shows how blood flows through the blood vessels in the brain |
MRV | Magnetic resonance venogram is an MRI that focuses on the veins |
The MRV is the test most directly matched to this condition because it looks specifically at the veins, but doctors often order more than one type of scan to get a complete picture of the brain's blood vessels.
How are intracranial venous malformations treated?
They are not usually treated because they rarely cause symptoms. If you have symptoms such as headaches, your healthcare professional might prescribe medicines. [2]
Rarely, people with an intracranial venous malformation have seizures or bleeding in the brain (a brain hemorrhage). These are usually caused by other vascular malformations that can be found with a venous malformation. Seizures are typically treated with medicines. Some hemorrhages require surgery, but many can be treated with medical management and observation in a hospital. [2]
Situation | What usually happens |
|---|---|
No symptoms | No treatment is usually needed |
Headaches or other symptoms | Medicines may be prescribed |
Seizures (rare) | Usually treated with medicines; often linked to another vascular malformation found alongside |
Brain hemorrhage (rare) | Some require surgery; many are treated with medical management and hospital observation |
Preparing for a doctor's appointment
Make an appointment if you have symptoms that worry you. If your healthcare professional thinks you might have an intracranial venous malformation, you may be referred to a neurologist or neurosurgeon. Before the visit, ask whether you need to do anything in advance, write down your symptoms (including ones that seem unrelated), key personal information such as major stresses or recent life changes, and every medicine, vitamin and supplement you take with doses. Consider bringing a family member or friend. Useful questions include: What other causes could explain my symptoms? What tests are needed to confirm the diagnosis? What are my treatment options, with pros and cons? What results can I expect? What follow-up should I expect? Your doctor may ask when your symptoms began, whether they are continuous or occasional, how severe they are, and what makes them better or worse. [2]
Talk with a healthcare professional. If you have headaches, seizures, vision changes or any new neurological symptom, see a doctor and ask what testing could explain it and what, if anything, needs follow-up. For more evidence-based health guides, visit Rinnit.com.
Frequently Asked Questions
What is an intracranial venous malformation?
An intracranial venous malformation is a vein in the brain that is unusually large. "Intracranial" means inside the skull. These larger veins usually work normally, are not likely to cause symptoms and rarely need treatment. Doctors also call them developmental venous anomalies.
Does everyone with one know they have it?
No. Some people have an intracranial venous malformation that is never diagnosed and never causes symptoms. Many are found by accident during a brain imaging test done for another condition.
What symptoms can it cause?
Most people never have symptoms. If symptoms occur, they may include headaches, seizures, dizziness, nausea and vomiting, muscle weakness or paralysis, loss of coordination, vision troubles, difficulty speaking and memory problems. Because these overlap with many other conditions, only imaging can confirm the cause.
What causes intracranial venous malformations?
Experts do not understand the exact cause. Certain genetic changes might play a role, and the malformations may form during fetal development. Other types are not inherited and are acquired later in life, possibly after an injury to the central nervous system.
Are they inherited?
A family history can increase your risk, but most types are not inherited. Hereditary hemorrhagic telangiectasia, Sturge-Weber syndrome and Klippel-Trenaunay syndrome can also increase the risk.
How are they diagnosed?
Intracranial venous malformations are found with imaging tests: a CT scan, an MRI, an MRA (an MRI focused on the arteries) and an MRV (an MRI focused on the veins). Doctors often use more than one scan to see the brain's blood vessels fully.
How are they treated?
Most do not need treatment because they rarely cause symptoms. If headaches occur, medicines may be prescribed. Rarely, seizures or brain hemorrhage happen, usually because of another vascular malformation found alongside the venous malformation.
What kind of doctor treats this?
You may be referred to a neurologist or neurosurgeon, doctors who specialize in diseases that affect the brain and nervous system.
Can a venous malformation cause a brain bleed?
Rarely. Seizures or bleeding in the brain in people with a venous malformation are usually caused by other vascular malformations that can be found alongside it. Some hemorrhages need surgery, but many are treated with medical management and observation in a hospital.
When should I see a doctor?
Seek medical attention if you have symptoms such as new headaches, seizures, weakness, vision changes or trouble speaking. They do not usually mean a venous malformation, but they deserve an explanation.
References
Mayo Clinic Staff. Intracranial venous malformations - Symptoms and causes. Mayo Clinic. September 20, 2024. https://www.mayoclinic.org/diseases-conditions/intracranial-venous-malformations/symptoms-causes/syc-20353336
Mayo Clinic Staff. Intracranial venous malformations - Diagnosis and treatment. Mayo Clinic. September 20, 2024. https://www.mayoclinic.org/diseases-conditions/intracranial-venous-malformations/diagnosis-treatment/drc-20353337
Agosti E, et al. Developmental venous anomaly associated with dural arteriovenous fistula: Etiopathogenesis and hemorrhagic risk. Front Surg. 2023;10:1141857. PMID 37025268. https://doi.org/10.3389/fsurg.2023.1141857
Hsu CC, et al. Symptomatic Developmental Venous Anomaly: State-of-the-Art Review on Genetics, Pathophysiology, and Imaging Approach to Diagnosis. AJNR Am J Neuroradiol. 2023;44(5):498-504. PMID 36997285. https://doi.org/10.3174/ajnr.A7829
Medical disclaimer
This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
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