An arteriovenous malformation (AVM) is a blood vessel disorder, that hampers blood flow and oxygen circulation. The arteries carry oxygen-rich blood from the heart to the brain and other vital organs. Whereas veins drain deoxygenated blood back to the lungs and heart. An arteriovenous malformation hinders this crucial process, and the adjacent tissues may not get adequate oxygen. Further, as the tangled blood vessels in an AVM do not function well, they become weak and rupture. If an AVM in the brain ruptures, it can result in bleeding in the brain, (haemorrhage) stroke, or brain damage. The exact cause of AVM is not clear and very rarely hereditary. Prompt diagnosis can help in treating AVM successfully and prevent or lessen the risk of complications.
Arteriovenous Malformation

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Symptoms

The symptoms of an AVM differ based on the region it’s affected. Mostly the initial symptoms appear after the bleeding develops. Besides bleeding symptoms can include:

  • Loss of neurological function
  • Headaches
  • Nausea and vomiting
  • Seizures
  • Loss of consciousness

Other possible symptoms include:

  • Muscles weakness
  • Paralysis in one region of the body
  • Loss of coordination
  • Difficulty performing tasks that require proper execution
  • Weakness in the lower extremities
  • Back pain
  • Dizziness
  • Vision problems
  • Problems with speech
  • Numbness, tingling or sudden pain
  • Memory loss
  • Hallucinations
  • Confusion
  • Children and adolescents may have problems with learning or behaviour

A type of AVM called a vein of Galen defect may cause symptoms that develop at or shortly after birth. A vein of Galen is located deep inside the brain and signs include:

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Causes

Arteriovenous malformations result from the development of irregular links between arteries and veins, but medical experts are not clear why this occurs. Certain genetic mutations may play a role; however, most types are not inherited.

Risk Factors

In very rare cases, a family history of AVMs can increase risk, but most types of AVMs are not genetically caused. Certain hereditary conditions can elevate the risk, and these include hereditary haemorrhagic telangiectasia, which is also called Osler-Weber-Rendu syndrome.

Complications

Bleeding and seizures are the most common complications. If left untreated, the bleeding can result in significant neurological damage and may be life-threatening.

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Diagnosis

The physician will completely evaluate the symptoms and do a physical examination to diagnose AVM. Also, the physician may listen for a sound called a bruit, which is a whooshing sound caused by fast blood flow via the arteries and veins of an AVM. Bruit can impede a person hearing or sleep or can even cause emotional issues.

Some of the tests commonly used to help diagnose AVM include:

Cerebral Angiography is also called arteriography, this procedure uses a special dye (contrast agent) that is injected into an artery.

CT scan provides detailed images of the head, brain or spinal cord and helps show bleeding.

CT angiography (CTA) is an imaging technique where a special dye aid to locate an AVM that is bleeding.

MRI uses potent magnets and radio waves to get detailed images of the tissues. This scan can identify even small changes in the tissues.

 Treatment

Generally, the treatment of AVM depends on where it is found, and the symptoms. Determine whether an AVM requires treatment involves several factors including: 

  • If the patient is bleeding
  • Have symptoms other than bleeding
  • It is located in a part of the brain that can safely receive treatment

Medications

Medications are prescribed that can help manage symptoms such as seizures, headaches and back pain.

Surgery

The chief mode of treatment for AVM is surgery. The doctor recommends surgery if there is a high risk of bleeding and surgery may help to remove AVM completely. Generally, surgery is done when the AVM is in an area where the surgeon can remove the AVM with minimal risk of causing major damage to the brain tissues.