Spinal arteriovenous malformation (AVM) is a tangle of blood vessels on, in or near the spinal cord. Without treatment, this rare condition can permanently damage the spinal cord.
Oxygen-rich blood usually enters the spinal cord through arteries, which branch into smaller blood vessels (capillaries). The spinal cord uses the oxygen from the blood in the capillaries. The blood then passes into veins that drain blood away from the spinal cord to the heart and lungs.
In a spinal AVM, the blood passes directly from the arteries to the veins and goes around the capillaries.
This change in blood flow means that the surrounding cells don't get the oxygen they need. The cells in the spinal tissue can weaken or die.
The tangled arteries and veins in a spinal AVM can also burst and cause bleeding in the spinal cord (hemorrhage). Sometimes, the AVM may grow over time as blood flow increases and presses on the spinal cord, leading to disability or other problems.
You might not know you have a spinal AVM unless you begin experiencing symptoms. The condition can be treated with surgery to stop or possibly undo some of the spinal damage.
Symptoms of spinal AVM can differ from person to person. Symptoms depend on where the AVM is found and how severe it is. Some people may not notice 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.
Symptoms may start suddenly or slowly. Symptoms usually include:
- Problems with walking or climbing stairs
- Numbness, tingling or sudden pain in the legs
- Weakness on one or both sides of the body
As the condition gets worse, you may have more symptoms including:
- Sudden, severe back pain
- Lack of feeling in the legs
- Difficulty urinating or having bowel movements
- Stiff neck
- Sensitivity to light
When to see a doctor
Make an appointment with your health care provider if you experience symptoms of spinal arteriovenous malformation.
The specific cause isn't known. Most spinal AVMs are present at birth (congenital), but others may happen later in life.
There are no known risk factors for spinal arteriovenous malformation. The condition occurs equally in men and women.
Without treatment, spinal arteriovenous malformation can cause disability that gets worse over time. This is from damage to the spinal cord and surrounding tissues. These problems may include:
- Difficulty 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 speed up spinal cord damage
Spinal arteriovenous malformations can be difficult to diagnose because the 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 caused by irregularly 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 the groin and guided to the spinal cord. Dye is injected into blood vessels in the 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 possible complications. The choice of treatment depends on the size, location and blood flow of your spinal AVM, the results of 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.
Pain-relieving medications may be used to reduce symptoms such as back pain and stiffness, but most spinal AVMs may eventually need surgery.
Surgery is usually needed to remove a spinal AVM from the surrounding tissue. There are three ways to remove spinal AVMs:
- Conventional surgery. In this procedure, a surgeon makes a cut in the skin to remove the AVM, taking care to avoid damaging the spinal cord and other surrounding areas. Surgery is usually done 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 radiologic 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 the leg and threaded to an artery in the spinal cord that is feeding the AVM. Small particles of a gluelike substance are injected to block the artery and reduce blood flow into the AVM. This procedure doesn't permanently destroy the AVM.
Your doctor may recommend endovascular embolization before other types of surgery to reduce the risk of bleeding during surgery or to shrink 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. Radiosurgery is most often used to treat small, unruptured AVMs.
Your doctor discusses with you the benefits and risks of surgery to remove your AVM. Because the AVM is so close to the spinal cord, spinal AVM surgery is a technically difficult and complex procedure that should be performed by an experienced neurosurgeon.
Preparing for an appointment
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 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 asking the questions you've prepared for your doctor, don't hesitate to ask other 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?