Spinal arteriovenous malformation (AVM) is a rare, abnormal tangle of blood vessels on, in or near the spinal cord. Without treatment, 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 the oxygen from the blood in your capillaries. The oxygen-depleted blood then passes into veins that drain blood away from your spinal cord to your heart and lungs.

In a spinal AVM, the blood passes directly from your arteries to your veins, bypassing the capillaries.

This disruption in blood flow deprives the surrounding cells of vital oxygen and causes cells in your spinal tissues to deteriorate or die.

The arteries and veins in a spinal AVM can also rupture and cause bleeding in the spinal cord (hemorrhage). Sometimes, the AVM may enlarge over time as blood flow increases and compress the spinal cord, leading to disability or other complications.

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.

Symptoms of spinal AVM vary greatly from person to person depending on the severity and location of the AVM. Some people may not develop noticeable symptoms for many years, if at all. Others may experience symptoms that are debilitating or life-threatening.

Symptoms usually develop when people are in their 20s, although almost 20% of people diagnosed with spinal AVM are under the age of 16.

The emergence 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:

• Sudden, severe back pain
• Lack of feeling in the legs
• Difficulty urinating or moving your bowels
• 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. Most spinal AVMs are present at birth (congenital), but others may occur later in life.

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

Untreated, spinal arteriovenous malformation can lead to progressive disability by damaging the spinal cord and surrounding tissues. 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

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 will likely recommend tests to help rule out other causes of your symptoms, including:

• Magnetic resonance imaging (MRI), which uses powerful magnets and radio waves to create detailed images of your spinal cord. A spinal MRI can identify a mass resulting from abnormally connected blood vessels associated with AVM.

• Angiography, which is usually needed to determine the location and characteristics of the blood vessels involved in the AVM.

  In an angiography, 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.

Treatment for spinal AVM may involve a combination of approaches to lessen symptoms as well as reduce the risk of potential complications. The choice of treatment will depend on the size, location and blood flow of your spinal AVM, your neurological exam, and your overall health.

The goal of spinal AVM treatment is to reduce the risk of hemorrhage and stop or prevent the progression of disability and other symptoms.

Medication

Pain-relieving medications may be used to reduce symptoms such as back pain and stiffness, but most spinal AVMs will eventually require surgery.

Surgery

Surgery is usually needed to remove a spinal AVM from the surrounding tissue. There are three ways to remove the spinal AVM:

• Conventional surgery. In this procedure, a surgeon makes an incision to remove the AVM, taking care to avoid damaging the spinal cord and other surrounding areas. Surgery is usually performed when the AVM is fairly small and in an area of the spinal cord that's easy to reach.

• Endovascular embolization. Endovascular embolization is a minimally invasive radiological procedure used to reduce the risk of hemorrhage and other complications associated with spinal AVMs.

  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. It doesn't permanently destroy the AVM.

  Your doctor may recommend endovascular embolization before conventional surgery to reduce the risk of bleeding during surgery or to reduce the size of the AVM so that surgery is more successful.

• Radiosurgery. This procedure uses radiation focused directly on the AVM to destroy the blood vessels of the malformation. Over time, those blood vessels break down and close up. Radiosurgery is most often used to treat small, unruptured AVMs.

Your doctor will discuss the benefits and risks of surgery to remove your AVM. The close proximity of the AVM to the spinal cord means spinal AVM surgery is a technically difficult and complex procedure that should be performed by an experienced neurosurgeon.

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 discuss in more detail. 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?