What Are Arteriovenous Malformations (AVMs)?

What Are Arteriovenous Malformations (AVMs)?

Arteriovenous malformations (AVMs) are abnormal tangles of the blood vessels that carry oxygen-rich blood throughout the body, disrupting blood flow and oxygen circulation. AVMs occur when a group of blood vessels is formed incorrectly during development before birth. In an AVM, arteries, and veins are connected directly and not through normal capillaries (small blood vessels). The causes of AVMs are unknown.

AVMs can occur anywhere in the body. AVMs that occur in the brain or spinal cord are the most likely to cause significant disability or long-term effects. Brain or spinal AVMs may not be diagnosed until they cause symptoms, which can be significant, as alterations of blood flow to the brain or spinal cord can result in seizures, numbness, and weakness.

Bleeding and hemorrhages are the most serious risk associated with AVMs. These are rare but can result in permanent neurologic disability or even death. AVMs can be treated successfully to alleviate symptoms and reduce or prevent the risk of complications.

Types of Vascular Malformations


“Vascular malformations” is a general term referring to blood vessel abnormalities that can be either congenital (present at birth) or acquired (develops throughout one’s life). They can cause functional or cosmetic problems.

Aside from arteriovenous malformations — tangles of blood vessels that cause abnormal connections between arteries and veins, disrupting blood flow and oxygen circulation — there are several other types of vascular malformations, including:

  • Cavernous malformations are clusters of abnormal small and larger blood vessels in the brain or spinal cord that may cause bleeding. They may not cause any symptoms, but sudden symptoms including severe headache, seizure, weakness in arms or legs, vision problems, and others require immediate medical attention.
  • Venous malformation (VMs) result from veins that have developed abnormally and may enlarge over time. Symptoms of VMs depend on the location within the body and can be painful and sensitive.
  • Hemangioma is a common birthmark that is made of extra blood vessels in the skin. It is a benign (non-cancerous) growth. Most hemangiomas appear during the first weeks of life and grow fast for the first few months then begin to shrink slowly. By age 10, many hemangiomas disappear or can hardly be noticed.
  • Dural AV fistula (dAVFs) are abnormal, direct connections between arteries and veins. These may occur in the brain, spinal cord, or other areas of the body. Dural AVFs typically occur later in life.

Symptoms, risks, potential complications, and treatments will vary depending on the type of vascular malformation.


Signs & Symptoms of AVMs


Many people with AVMs have no initial symptoms. Symptoms of AVMs depend on the location within the body. Signs and symptoms of AVM may include:

  • Bleeding
  • Headache
  • Seizures
  • Buzzing or rushing sound in the ears
  • Changes in vision
  • Facial paralysis
  • Drooping eyelids
  • Problems speaking
  • Difficulties with memory or thinking
  • Changes in the sense of smell
  • Backache
  • Numbness, pain, or tingling in the body
  • Muscle weakness
  • Dizziness
  • Loss of consciousness
  • Problems with balance or coordination

Complications & Risks

Complications & Risks

AVMs come with several risks and complications. These are rare but can be quite serious. AVM complications and risks may include:

  • Hemorrhagic stroke is caused by weakened blood vessels that rupture and bleed into the brain. This is a rare but serious complication of AVMs and can be fatal.
  • Hydrocephalus refers to a buildup of cerebrospinal fluid (CSF) in unruptured brain AVMs.
  • Seizures can also occur as a result of AVMs.
  • Developmental delays may occur in children with AVMs.
Get Care

Trust NewYork-Presbyterian for Arteriovenous Malformation Care

At NewYork-Presbyterian, our board-certified physicians and neurologists can help to guide you through diagnosis and treatment for arteriovenous malformations.

Learn more about arteriovenous malformations (AVM) care, the Neurology and Neurosurgery program at NewYork-Presbyterian, and treatments for neurological conditions. Call us today to schedule an appointment.