An AVM is a tangle of abnormal blood vessels. Normally blood is pumped from the heart at a high pressure through arteries until it

reaches small vessels called capillaries. 

As the blood flows through the capillaries they join the veins, which return the blood to the heart and lungs. AVM’s disrupt this blood flow process. They can occur anywhere in the body and AVM’s that occur in the brain are known as cerebral AVM’s. They are of special concern because of the damage they cause when they bleed.

The cause of an AVM is not known but they are thought to develop during pregnancy or soon after birth. AVM’s are not inherited or infectious and do not spread to other parts of the body.

Symptoms differ in each individual, varying upon where the AVM is.

Headaches and seizures are the most common symptom of a cerebral AVM. Other symptoms include muscle weakness, coordination

problems, dizziness, visual disturbance and abnormal sensations, such as numbness, tingling or pain. Some AVMs go undetected and are only recognised through other investigations and therefore may not shown any signs or symptoms. Others may be detected once the AVM has caused a problem.

AVMs can damage the brain or spinal cord by three different ways.

1. By reducing the amount of oxygen needed by the brain. The amount of oxygen that is delivered to the brain and spinal cord is altered due to the abnormal flow of blood through the arteries and veins. Because of this, the oxygen which is required by brain tissue is starved.
2. By causing bleeding into the surrounding tissues. Bleeding can occur from the force of the blood flowing though the thin blood vessels. The blood vessel wall may balloon (aneurysm) and are at risk of bursting. Depending upon the location of the AVM and the amount it bleeds depends upon the severity of problems caused. If a large enough volume of blood escapes from an AVM into the surrounding brain, this can result in a stroke or possible death.
3. AVMs can also cause significant problems as they can press or move parts of the brain or spinal cord.

Future risks

AVMs are not predictable. Some investigations may show a higher or lower risk of complications. Your doctor will advise you on the most suitable precautions.

Medication can help to ease symptoms such as headache, back pain,seizures etc. 

There are several treatment options available but treatment will depend on the size and location of the AVM. You will be advised on the most suitable option

Embolisation

Embolisation involves injecting liquid glue or coils into the AVM using a catheter to block the flow of blood through the AVM.

Radiation/Stereotactic Surgery

This is also known as Gamma Knife Surgery, which involves narrow x-ray beams being focused on the AVM

Surgery

Surgery is used to remove the AVM under a general anaesthetic.

Observation

Observation may be recommended if the neurosurgeon feels that other treatment can not be offered safely.  

Treatment is offered to prevent brain injury, however there is currently no treatment which exists that can repair damage already caused by an AVM. Seizures may continue and patients with neurological problems will still be likely to have problems after treatment, although improvement can occur.

You can download the information on this page as a PDF leaflet.pdf