Venous anomaly (DVA) seen by chance on a brain MRI

What the report words mean

Developmental venous anomaly (DVA). A group of small veins (medullary veins) that fan out like spokes and join one larger collecting vein, which drains into the normal veins of the brain. It drains normal brain tissue. (Meng 2014) Reviews call it the most common slow-flow vein malformation in the brain and an extreme variation of normal anatomy. (Hsu 2023)(Aoki 2016)
Venous angioma. An older name for the same thing. (Aoki 2016)
Caput medusae or "Medusa head". How the spoke-like veins look on the scan, often clearest after a contrast injection. (Meng 2014)(Hsu 2023)
Supratentorial or infratentorial. Above or below the tentorium, the sheet of tissue that separates the main brain from the cerebellum and brainstem at the back. In a Polish study, 73% were above it and the frontal lobe was the most common place. (Brzegowy 2021)
Signal change or FLAIR hyperintensity next to the DVA. A brighter area on some MRI sequences in the brain tissue the DVA drains. It was seen next to about 5% of DVAs in one study. (Brzegowy 2021) White matter spots elsewhere in the brain are covered on white matter changes on a brain MRI.
Associated cavernoma or cavernous malformation (CCM). A separate small cluster of leaky blood vessels in the area the DVA drains. See a nearby cavernoma below. (Meng 2014)(NHS cavernoma)

How common it is, by age and sex

How often a DVA is found depends on who is scanned and which MRI is used. In the Rhineland Study in Germany, which scanned 3589 people aged 30 and over (average age 55) from the general population, 89 people (2.5%) had a DVA. Women (2.4%) and men (2.6%) had it about equally often, and most people with one had only one. (Rhineland 2022) In a Norwegian study of 1006 adults aged 50 to 66, 4 (0.4%) had one. (HUNT MRI 2016)

Hospital studies find more. A Polish study of 6948 adult head MRIs found at least one DVA in 7.5%, and it was found less often in older age groups. (Brzegowy 2021) A review gives 2.6% to 6.4%. (Hsu 2023) In a review of 165,230 MRI reports in Beijing, 1.1% mentioned a DVA, and 51% of those people were men. (Meng 2014) A US study of 18,073 contrast MRIs found:

Share of people with a DVA on a contrast brain MRI, by age (Brinjikji 2017a)
Age	With a DVA
Under 1 year	1.5%
1 to 5	7.1%
6 to 17	9.6%
18 and over	9.6%

The authors suggest DVAs may form in early childhood rather than before birth. (Brinjikji 2017a)

Why most cause no symptoms

It drains normal brain. The veins do the same job as ordinary veins, just in an unusual pattern. (Meng 2014)(Aoki 2016)
Found by chance. In a Scottish population study of 93 adults first diagnosed with a DVA, 98% were found by chance, 1% with a bleed and 1% with a stroke. In 492 person-years of follow-up there were no bleeds or strokes. (Hon 2009)
Low bleeding rate. In studies that followed 422 people with a DVA, the bleeding rate after it was found ranged from 0% to 1.28% a year. (Hon 2009)
Symptoms are uncommon. A review says the overwhelming majority cause no symptoms, and that hospital case series probably overstate how often they do. (Hsu 2023)
Worry is real. See after an abnormal screening result.

How a nearby cavernoma changes things

A cavernoma is a cluster of abnormal blood vessels, usually in the brain or spinal cord, that looks like a raspberry on a scan and can leak blood. It often causes no symptoms, and many are found on an MRI done for another reason. (NHS cavernoma) Cavernomas affect about 16 to 50 in 10,000 people. People with the family form usually have several, and people with the non-inherited form usually have one. (MedlinePlus Genetics)

How often they come together. A cavernoma was found with the DVA in 4.1% of people with a DVA in a Polish study, 6.9% in a US study and 11.1% in a Beijing study. In the Beijing study, 2.2% of people without a DVA had a cavernoma. (Brzegowy 2021)(Brinjikji 2017b)(Meng 2014)
Age. In the US study, a cavernoma with the DVA was found in 0.8% of people with a DVA aged up to 10, 7.5% aged 21 to 30 and 11.6% over 70. The authors think these cavernomas form during life. (Brinjikji 2017b)
DVA features. In the Beijing study a cavernoma was more likely when 3 or more of the small veins showed in one MRI slice, when the DVA was below the tentorium, or when there was more than one DVA. (Meng 2014)
Bleeding. The NHS says a cavernoma that has never bled has an estimated chance of bleeding of under 1% a year, and one that has bled before has a chance of 4% to 25% a year, falling over time without further bleeds. Most bleeds are small. About 1 in 600 people in the UK has a cavernoma without symptoms. (NHS cavernoma)
Symptoms to know. The NHS lists seizures, headaches, dizziness, slurred speech, double vision, balance problems, weakness or numbness, and stroke, and says to get medical help as soon as possible if you have any of them for the first time. (NHS cavernoma)

When a repeat scan or referral is suggested

A DVA on its own. A UK population study and review called the presentation and course of DVAs benign. (Hon 2009)
Some authors suggest a repeat MRI. The Beijing study authors advise follow-up MRI for every DVA to look for a cavernoma forming. (Meng 2014)
With a cavernoma. The NHS says to watch for new symptoms, which may be a sign of a bleed. Your doctor can advise what to do if you get new or worse symptoms and may suggest another brain scan. (NHS cavernoma)
Your doctor decides. Whether another scan or a referral is needed depends on your symptoms, the rest of the report and whether a cavernoma or other finding is mentioned.

The NHS says to call 999 (in the US, call 911) if you think you or someone else is having a stroke, or had stroke signs in the last 24 hours even if they stopped. Remember FAST: face drooping, arm weakness, speech problems, time to call 999 (in the US, call 911). (NHS, stroke symptoms) It also says to call 999 (in the US, call 911) if you think someone is having a seizure and it is the first time it has happened, or it lasts longer than is usual for them, or longer than 5 minutes if you do not know how long their seizures usually last. (NHS, epilepsy) Elsewhere, call your local emergency number.

Other things a brain scan may show

The same scan may mention other chance findings, each with its own page: a small brain aneurysm, white matter changes, a small meningioma, low-lying cerebellar tonsils or Chiari I, an arachnoid cyst and a pineal cyst.

Who it applies to

Adults told that a brain MRI or CT, done for something else, shows a developmental venous anomaly or venous angioma. Children, people already being seen for a cavernoma or a family history of cavernomas, and a scan done because of a bleed, seizure or new weakness are outside this page.

Routine age-based screening

A brain finding on a scan does not replace the routine screenings for your age. See screenings by age and gender.

Where they differ:

How common it is. A general population study found 2.5% of adults, (Rhineland 2022) hospital MRI studies found 7.5% and, with contrast, 9.6%, (Brzegowy 2021)(Brinjikji 2017a) and a review of MRI reports found 1.1%. (Meng 2014) Studies used different scanners, sequences and reasons for the scan.
Age. A US contrast MRI study found the same share in older children and adults, (Brinjikji 2017a) while a Polish study found it less often in older adults. (Brzegowy 2021)
How often a cavernoma comes with it. 4.1%, 6.9% and 11.1% in three studies. (Brzegowy 2021)(Brinjikji 2017b)(Meng 2014)
Follow-up. The Beijing study authors advise a repeat MRI for every DVA, (Meng 2014) while a UK population study and review found a benign course. (Hon 2009)

Your doctor decides what your result means for you.

Questions people ask

What is a developmental venous anomaly?

It is an unusual pattern of veins in the brain: a group of small veins that fan out like spokes and join one larger collecting vein. It drains normal brain tissue. It was previously called a venous angioma, and many experts see it as an extreme variation of normal anatomy rather than a disease. (Meng 2014) (Hsu 2023) (Aoki 2016)

How common is it?

It depends on the scan. A German population study of 3589 adults found one in 2.5%, a Polish study of 6948 adult head MRIs found 7.5%, and a US study of contrast MRIs found 9.6% of adults. Women and men had it about equally often in the German study. (Rhineland 2022) (Brzegowy 2021) (Brinjikji 2017a)

Does a DVA cause symptoms?

Almost always not. In a Scottish population study of 93 adults, 98% were found by chance, and there were no bleeds or strokes in 492 person-years of follow-up. Your doctor decides what your result means for you. (Hon 2009) (Hsu 2023)

Why does the report mention a cavernoma?

A cavernoma (cavernous malformation) is a small cluster of leaky blood vessels that is sometimes found next to a DVA. Studies found one with 4% to 11% of DVAs, more often in older people. A cavernoma can bleed, so a report usually says whether one is there. (Brzegowy 2021) (Brinjikji 2017b) (Meng 2014) (NHS cavernoma)

When should I get urgent help?

The NHS says to call 999 (in the US, call 911) if you think someone is having a stroke, using FAST: face drooping, arm weakness, speech problems, time to call. It also says to call 999 (in the US, call 911) for a first seizure or one lasting more than 5 minutes. (NHS, stroke symptoms) (NHS, epilepsy)