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Health > Conditions > A > Arterio-venous malformation (AVM)                          Arterio-venous malformation (AVM)An arterio-venous malformation, or AVM, is a rare condition which affects less than one per cent of people. It happens when the blood vessels which carry oxygen-rich blood (arteries) become tangled with the vessels which take the blood back to your heart and lungs (veins). Many AVMs are never spotted and do not cause any symptoms. However, if the tangle of blood vessels is in your brain or backbone then they can have an impact on your health. What causes an AVMand who can get it?Normally, arteries and veins are connected by a web of smaller and smaller vessels (capillaries) which slow down your blood and take oxygen deep into your muscles and organs. Experts think an AVM forms when these capillaries are missing and blood flows very quickly from your arteries straight into your veins. The arteries and veins within an AVM do not work normally, which means they do not transport blood and oxygen to or from an organ. AVMs range from millimetres to more than 6.5 centimetres (2.5 inches) in size. It is not known at the moment what causes AVMs and why certain patients develop abnormal blood vessels and others don’t. It seems that they are not passed on from parents to children and they are not infectious, so you can not catch an AVM off someone who already has one. What are the signs and symptoms of an AVM?Many AVMs are never spotted and do not cause any symptoms. If you have any sign at all it is likely to be a headache or possibly a seizure. In rare cases there can be more serious symptoms, especially if the AVM is pressing on the brain or spine. There is also a risk that one of the vessels will burst and bleed (Haemorrhage). In that case symptoms can include:
How is it normally diagnosed and treated?Often, AVMs are never diagnosed because they don’t cause any symptoms. Sometimes they are found by accident when you are being treated for something else. If a doctor suspects you have an AVM they can look for it with a brain scan or a type of X-ray called an angiogram. As for treatment, the doctor has to carefully evaluate the risks and benefits of treatment for your AVM before choosing how to tackle the AVM. Firstly, medicines can be used to help symptoms like headaches, back pains and seizures. To actually remove or stop the blood supply to the AVM, however, you will need surgery. There are 3 main surgical choices:
The first option, endovascular embolisation, means guiding a tiny tube through your blood vessels and into the AVM. Once there, glue or small metal coils are used to stop the blood flowing through the AVM and block off the abnormal vessels. During conventional surgery the AVM is removed in an operation. Radiosurgery involves aiming a beam of radiation at the AVM. The blood vessels will eventually close up over a time period of two-three years. It is safe to remove the abnormal vessels within the AVM, since they do not have any functions. But surgeons have to be careful not to affect the normal vessels of the brain. This is why not all treatments are suitable in every case. Doctors will need to carefully evaluate your tests before they offer any treatment. Sometimes, treatment might not be necessary at all or too risky. In that case regular check-ups will be carried out. When should I seek medical help?If you have regular headaches or unexplained seizures then it is best to ask for help from your doctor. Looking forwardMany people live with AVMs but there are risks, the biggest of which is bleeding. If the AVM bleeds in the brain it can cause brain damage, so it is important to discuss treatment options with your doctor.
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