By Mayo Clinic Staff

Spinal arteriovenous malformation (AVM) is a rare, abnormal tangle of blood vessels on, in or near the spinal cord. Untreated, spinal AVM can permanently damage your spinal cord.

Oxygen-rich blood normally enters your spinal cord through arteries, which branch into smaller blood vessels (capillaries). Your spinal cord uses oxygen from the blood in your capillaries, and this oxygen-depleted blood then passes into veins that drain blood from your spinal cord to your heart and lungs. In a spinal AVM, your blood passes directly from your arteries to your veins, bypassing capillaries.

This disruption in blood flow causes cells in your spinal tissues to deteriorate or die. The arteries and veins in a spinal AVM can rupture, which results in bleeding in the spinal cord (hemorrhage). Sometimes, the AVM enlarges and compresses the spinal cord.

Spinal AVM can go undiagnosed unless you begin experiencing signs and symptoms. The condition can be treated with surgery to halt or possibly reverse some of the spinal damage.

Most people with spinal AVM experience few if any significant symptoms.

When symptoms do occur, they vary depending on the severity and location of the AVM. These symptoms usually appear when people are in their 20s, although almost 20 percent of people diagnosed with spinal AVM are under the age of 16.

The onset of symptoms may be sudden or gradual. Symptoms typically include:

  • Problems with walking or climbing stairs
  • Numbness, tingling or sudden pain in your legs
  • Weakness on one or both sides of your body

As the condition progresses, additional symptoms may include:

  • Lack of feeling in the legs
  • Difficulty urinating or moving your bowels
  • Lower back pain
  • Headache
  • Stiff neck
  • Sensitivity to light

When to see a doctor

Make an appointment with your doctor if you experience signs and symptoms of spinal arteriovenous malformation.

The specific cause isn't known. Spinal AVM was previously thought to be present from birth (congenital), but researchers are no longer sure that is the case.

There are no known risk factors for spinal arteriovenous malformation. The condition occurs equally in men and women.

Untreated, spinal arteriovenous malformations can lead to progressive disability. Specific complications may include:

  • Problems with moving (motor deficits)
  • Pain, tingling and numbness (sensory deficits)
  • Spinal column deformity
  • Bulging blood vessel (aneurysm)
  • High blood pressure in the veins (venous hypertension), which can cause fluid accumulation (edema) and tissue death due to lack of oxygen (spinal cord infarction)
  • Hemorrhage, which can accelerate spinal cord damage

You may be referred to a doctor who specializes in disorders of the brain and nervous system (neurologist).

What you can do

  • Write down your symptoms, including any that may seem unrelated to the reason why you scheduled the appointment.
  • Make a list of all your medications, vitamins and supplements.
  • Write down your key medical information, including other conditions.
  • Write down key personal information, including any recent changes or stressors in your life.
  • Write down questions to ask your doctor.

Questions to ask your doctor

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need?
  • What treatments are available, and what types of side effects can I expect?
  • I have other health conditions. How can I best manage these conditions together?
  • Should I restrict my activities?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to go over points you want to spend more time on. You may be asked:

  • Have you experienced problems with walking or had weakness in your legs?
  • Have you had numbness, tingling or pain in your legs?
  • Have you had headaches or back pain?
  • When did you begin experiencing these symptoms? Have they been continuous or occasional?
  • Do your symptoms worsen when you exercise?

Spinal arteriovenous malformations can be difficult to diagnose because signs and symptoms are similar to those of other spinal conditions, such as spinal dural arteriovenous fistula, spinal stenosis, multiple sclerosis or a spinal cord tumor.

Your doctor is likely to recommend:

  • MRI, which can identify a mass resulting from abnormally connected blood vessels.
  • Angiography, which is usually needed to determine the location and characteristics of the blood vessels involved in the AVM. A thin tube (catheter) is inserted into an artery in your groin and guided to your spinal cord. Dye is injected into blood vessels in your spinal cord to make them visible under X-ray imaging.

Surgery is usually needed to remove a spinal AVM from surrounding tissue.

Before surgery, your doctor may recommend endovascular embolization. This is a procedure to reduce the chance of bleeding during surgery or reduce the size of the AVM so that surgery is more successful.

In endovascular embolization, a catheter is inserted into an artery in your leg and threaded to an artery in your spinal cord that is feeding your AVM. Small particles of a glue-like substance are injected to block the artery and reduce blood flow into the AVM.

If the AVM can't be completely removed surgically, your doctor may recommend radiation therapy to shrink the lesion.

  • Experience. Each year, Mayo Clinic specialists treat more than 40 people with this rare condition.
  • Imaging expertise. Mayo Clinic has radiologists who specialize in neurological disorders. These specialists have experience distinguishing between spinal arteriovenous malformations and other spinal lesions.
  • Surgical technique. Often, a combination of treatments can provide the best treatment results. Mayo has neurosurgeons with experience in surgical and other techniques for treating spinal arteriovenous malformations.
  • New ideas. Mayo Clinic researchers are working to improve diagnosis and treatment of spinal arteriovenous malformations. You have access to the expertise of Mayo's clinician-researchers.

Mayo Clinic in Rochester, Minn., ranks No. 1 for neurology and neurosurgery in the U.S. News & World Report Best Hospitals rankings. Mayo Clinic in Scottsdale, Ariz., and Mayo Clinic in Jacksonville, Fla., are ranked among the Best Hospitals for neurology and neurosurgery by U.S. News & World Report. Mayo Clinic also ranks among the Best Children's Hospitals for neurology and neurosurgery.

Mayo Clinic works with hundreds of insurance companies and is an in-network provider for millions of people. In most cases, Mayo Clinic doesn't require a physician referral. Some insurers require referrals or may have additional requirements for certain medical care. All appointments are prioritized on the basis of medical need.

Specialists in neurology at Mayo Clinic in Arizona diagnose and treat adults with spinal arteriovenous malformations.

For appointments or more information, call the Central Appointment Office at 800-446-2279 (toll-free) 8 a.m. to 5 p.m. Mountain Standard Time, Monday through Friday or complete an online appointment request form.

Specialists in neurology at Mayo Clinic in Florida diagnose and treat adults with spinal arteriovenous malformations.

For appointments or more information, call the Central Appointment Office at 904-953-0853 8 a.m. to 5 p.m. Eastern time, Monday through Friday or complete an online appointment request form.

Specialists in neurology at Mayo Clinic in Minnesota diagnose and treat adults and children with spinal arteriovenous malformations.

7 a.m. to 6 p.m. Central time, Monday through Friday

See information on patient services at the three Mayo Clinic locations, including transportation options and lodging.

Clinical trials are research studies that test new ways to detect, prevent or treat disease. Mayo Clinic conducts more than 3,000 clinical trials and research studies each year and often coordinates national clinical trials with other medical centers.

Learn more about clinical trials and whether Mayo Clinic may be conducting a clinical trial related to your condition or procedure.

Mayo Clinic researchers are working to improve diagnosis and treatment of spinal arteriovenous malformations. Specific efforts involve imaging techniques to differentiate spinal AVM from other spinal conditions, and techniques for successful embolization of spinal AVM .

Read more about Mayo's research in neurology and neurosurgery.

See a list of publications by Mayo Clinic doctors on spinal arteriovenous malformations on PubMed, a service of the National Library of Medicine.

April 25, 2014