Arteriovenous Malformations

Arteriovenous Malformations (AVMs) are abnormal clusters of vessels (the nidus) located within the brain (or occasionally spine) through which blood passes rapidly without supplying the brain tissue.  The propensity for these AVMs to develop is probably present at birth but grow over time.

Arteriovenous Malformations


AVMs can present in several ways.  Most commonly they present when they bleed, caused by rupture of the tiny vessels within the nidus. Other presentations include seizures or headaches, which in both cases would have led to an MRI scan on which the diagnosis is made.

Click here to learn more about Paediatric AVMs.


Once diagnosed by MRI scan, most patients will need a catheter angiogram to investigate the AVM and its nidus and other features fully. This procedure is performed as a day case under local anaesthetic, with a long catheter being passed from the artery at the top of the leg to take x-ray pictures of the brain arteries.

Decision making about the treatment options of AVMs of the brain and spine is complex and depend on numerous factors such as whether it has bled, the future risk of bleeding, the size and other angiographic features of the AVM and the patient’s age/medical history.

Four options exist for treatment of brain AVMs:

  • Endovascular embolisation. Insertion of small catheters into the brain arteries to inject a liquid to block up the abnormal connections.
  • Open surgery to remove the AVM. This is the most definitive method to treat AVMs, and is often combined with a pre-operative embolisation to tackle deeper and more difficult to reach sections to make the subsequent surgery easier.
  • Stereotactic radiosurgery. The use of high dose concentrated radiation treatment to gradually shrink the AVM.  This is effective at treating many AVMs but is limited by the slow effect (often over 2 or 3 years).
  • No treatment, and continue to observe the AVM often with serial MRI scans.

All treatment modalities are present at The National Hospital for Neurology and Neurosurgery. Most patients find a combined consultation with Dr Adam Rennie and a Consultant Neurosurgeon useful in the decision making process. In addition all cases are fully discussed in the NHNN neurovascular multidisciplinary meeting.