WHAT IS BRAIN AVM?
An arteriovenous malformation, AVM, is an abnormal connection between arteries and veins. It involves a defect in the blood vessel system thought to occur mostly during fetal development – but cases where and AVM has developed later in life have also been reported.1
Normally, arteries, blood vessels that carry oxygenated blood to the brain, are connected to the veins, blood vessels that drain oxygen-depleted blood away from the brain, through a system of small blood vessels known as capillaries2
However, in an AVM, such a capillary system is absent, and blood gets shunted from the arteries directly to the veins.2
This causes a high-flow system, which can lead to potentially life-threatening hemorrhage (bleeding),2 especially in young adults.3
The main purpose of treating AVM should be to prevent new or recurring hemorrhage.3
Normalblood vessels
blood vessels
IN A bAVM
AVM SYMPTOMS
In most cases of AVM, patients do not experience any symptoms.1
- However, in some affected patients, AVM can cause symptoms such as seizures and headaches.4
- Seizures can be total or partial and can involve a loss of control over movement, convulsions or even change in the level of consciousness.4 Headaches can differ considerably in intensity, duration and frequency.
- Sometimes, the headache may be linked to the site of the AVM. However,more frequently, it affects the entire head.4
- Some patients may experience neurological symptoms depending on the location of the AVM, such as:4
- Muscle weakness or paralysis in one part of the body
- Visual problems such as loss of a part of visual field Problem understanding or using language
- Abnormal sensations (numbness, tingling or spontaneous pain)
- Mental confusion
- Dementia
- Loss of coordination (gait disturbances)
- Difficulty carrying out tasks that need planning
- Inability to control eye movement
- Memory deficits
- Hallucination
An AVM can produce symptoms at any age, but usually they manifest in the age group of about 20–50 years.4
An AVM that does not produce symptoms by the age of about 50 years, may remain stable and not produce any symptoms at all.4
AVM TREATMENT OPTIONS
Monitoring:
If the risk of hemorrhage is low, an AVM can be monitored with no medical intervention.
Conventional Surgery:
Surgery involves removing the central parts of the AVM ensuring minimal damage to the surrounding tissues, and is usually an option when the AVM is relatively small, and located in an easily accessible part of the brain.1
Endovascular Technique (Pre-surgical or Pre-radiosurgical Embolization)
Embolization is a technique used for an AVM that is not easily accessible because it’s located deep inside the brain. In this process, your doctor inserts a long, thin tube (catheter) into a groin artery and threads it through blood vessels to your brain using X-ray imaging.4 Your surgeon positions the catheter in one of the feeding arteries to the AVM, and injects an embolizing agent – either solid or liquid – to block the artery and reduce blood flow into the AVM.
- Usually, embolization does not permanently eliminate an AVM – it’s used to reduce the blood flow through the AVM and facilitate its surgical removal through surgery or radiosurgery.
- Your doctor will decide which type of embolic material is best suited to your presurgical embolization procedure.
Szajner M, Roman T, Markowicz J, et al. Onyx® in endovascular treatment of cerebral arteriovenous malformations - a review. Pol J Radiol. 2013;78(3):35–41.
Nussbaum ES. Vascular malformations of the brain. Minn Med. 2013;96(5):40–43.
Kim H, Marchuk DA, Pawlikowska L, et al. Genetic considerations relevant to intracranial hemorrhage and brain arteriovenous malformations. Acta Neurochir Suppl. 2008;105:199–206.
Arteriovenous malformations and other vascular lesions of the central nervous system fact sheet. Available at: https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Arteriovenous-Malformation-Fact-Sheet. Accessed on: November 14, 2013.