The risk of stroke is reduced if AVM not treated

New research has shown that people with the condition arteriovenous malformation (AVM), which causes blood vessels in the brain to tangle, have a better outcome if only their symptoms are treated and not the AVM itself.

A team of doctors looked at the long-term outcome of patients with the condition, which is caused by abnormal connections between the arteries and veins in the brain. They found that, over a 12 year period, patients who chose not to be treated for their condition were less likely to have a stroke or die from related causes. These patients were also less likely to suffer sustained disability compared with those who opted for an intervention to treat the tangles.

This is the first study to compare the risks and benefits of treatment for AVM in the long term. The findings build on previous research that reported an increased risk of stroke in the first three years after treatment for AVM.

AVM affects around 1 in 2000 people. Although most people with the condition can lead relatively normal lives, they live with the risk that the tangles can burst and bleed into the brain at any time, causing a stroke. Around one in every hundred AVM patients suffers a stroke each year.

In some cases doctors can surgically remove the tangle or block the blood vessels involved to reduce the risk of bleeding. However, treatment can sometimes increase the chances that the tangle will burst and bleed into the brain, resulting in a stroke.

Professor Rustam Al-Shahi Salman, MRC Senior Clinical Fellow at the University of Edinburgh and a consultant neurologist, said: "Many patients feel that living with AVM is like living with a time bomb in your head that could explode at any time. Patients and their doctors face difficult choices when deciding whether or not to pursue treatment. We have found that, for most people whose AVM has not caused a bleed, the risks of treatment exceed the risks of leaving it alone over 12 years."

The study was led by researchers at the University of Edinburgh and is published in the Journal of the American Medical Association.

A group of veins and arteries with abnormal connections between the two. Full medical glossary
A fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. Full medical glossary
A doctor who specialises in disorders of the nervous system. Full medical glossary
Any sudden neurological problem caused by a bleed or a clot in a blood vessel. Full medical glossary
A specialist in the treatment of diseases of the urinary tract, the channels that carry urine from the kidneys to the outside of the body. Full medical glossary
A blood vessel that carries blood towards the heart. Full medical glossary
Relating to the veins. Full medical glossary