Arteriovenous Malformations (AVMs) Symptoms & Causes in Children

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How common are AVMs?

AVMs are relatively rare birth defects. They occur approximately once in every 500 births.

What are the symptoms of AVMs?

AVMs often appear as a stain on the child's skin at birth which enlarges in childhood and adolescence.AVMs develop before birth. Usually an AVM is seen as an innocent stain on your child’s skin at birth; often they begin to enlarge in childhood and adolescence.

  • Intracranial (within the head) AVMs have no visible symptoms. However, they may cause headaches or sudden bleeding into the brain.
  • AVMs outside the brain appear more slowly with color changes, then bleeding and persistent pain.

In time, if the blood flow through an AVM is excessive, your child’s heart can become overworked.

AVMs can occur in any organ in the body. They occur most frequently in the parts of the body below (in order of frequency):

  • Head
  • Limbs
  • Trunk
  • Internal organs

AVM LegIn infancy and childhood, the blush of an AVM can be mistaken for hemangioma (the most common tumor in babies).

  • The AVM becomes obvious as signs of fast blood flow appear. The skin becomes a darker red or purple color, nearby veins enlarge a mass appears beneath the stain, and there is local warmth.

What problems are associated with AVMs?

Hereditary hemorrhagic telangiectasia (HHT) — A fairly common familiar vascular disorder. Children with HHT can develop AVMs in the lungs, brain, and gastrointestinal track.

Parkes Weber syndrome — In this disorder, several AVMs plus overgrowth of a limb combine to put extra strain on the heart.

Our research collaborators have identified a gene that is changed in about one half of the patients with this syndrome.
  • Wyburn-Mason syndrome (also called Bonnet-Dechaume-Blanc syndrome) — A rare combination of a vascular abnormality in the retina and an AVM in the brain.
It’s sometimes accompanied by a facial capillary stain and/or overgrowth on one side of the body.
  • Cobb syndrome — The combination of a cavernous malformation (fragile arteries/veins) of the skin with an AVM of the spinal cord.

What causes AVMs?

We don’t really know. They are believed to be caused by a mistake in the formation of the normal connections between arteries, veins and capillaries that occurs during early embryonic life.

No known food, medication, or activity during pregnancy can cause an AVM. 

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