Spinal arteriovenous malformation
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Arteriovenous malformations (AVM) are abnormal connections between arteries and veins that form tangles of blood vessels. Although they can occur anywhere in the body, they are most commonly found in the brain and spinal cord. Some people with AVMs experience symptoms, while others only become aware of the condition after a brain bleed or other event.
Normally, oxygen-rich blood enters the spinal cord through arteries and flows into smaller blood vessels known as capillaries. The spinal cord uses the oxygen from the blood before it is drained away by veins to the heart and lungs. In spinal AVMs, however, blood flows directly from arteries to veins, bypassing the capillaries. This disrupts the delivery of oxygen to the surrounding cells, leading to tissue damage or cell death.
In addition to the lack of oxygen delivery, the tangled arteries and veins of spinal AVMs can also burst and cause bleeding in the spinal cord. Over time, the AVM may grow, causing increased blood flow and pressure on the spinal cord, leading to disability and other complications. Although some people may not experience symptoms, spinal AVM can be treated with surgery to prevent or reverse some of the damage caused by the condition.
Symptoms
Spinal AVM symptoms vary among individuals depending on the location and severity of the arteriovenous malformation, with some people remaining asymptomatic for many years or never experiencing symptoms. However, for others, the symptoms can be severe and even life-threatening. Most individuals tend to develop symptoms in their 20s, but approximately 20% of those diagnosed with spinal AVM are under 16 years of age.
Symptoms may appear gradually or sudden. Symptoms may include:
- Sudden, severe back pain
- Weakness or paralysis in the affected nerves of the body
- Difficulty in walking or climbing the stairs
- Numbness, tingling or sudden pain in the legs
- Difficulty urinating or bowel movements
- Headache
- Stiff neck
- Sensitivity to light
It is recommended to seek medical attention if the patient is experiencing any symptoms of the spinal AVM.
Causes
Arteriovenous malformations (AVM) are believed to be congenital, developing during pregnancy, and their exact cause is unknown. Although rare cases have been linked to head trauma or certain infections, the majority of AVM are not associated with any particular risk factor. Additionally, hereditary factors are only believed to play a role in a small number of cases, with AVM typically not running in families.
Risk factors
While no specific risk factors for spinal arteriovenous malformation (AVM) have been identified, the condition typically affects younger individuals between the ages of 20 and 40, with those between the ages of 40 and 50 being particularly prone to experiencing symptoms.
Diagnosis
Due to the symptoms being similar to those of other spinal disorders, such as spinal stenosis, multiple sclerosis, spinal dural arteriovenous fistula, and spinal cord tumors, diagnosing spinal arteriovenous malformations can be challenging.
- Physical examination: The healthcare provider will discuss symptoms and perform a physical examination, occasionally listening for a bruit, which is the sound of rapid blood flow caused by an AVM in arteries and veins.
- Imaging test:
- Magnetic resonance imaging (MRI): which uses strong magnets and radio waves, can generate precise pictures of the spinal cord and help identify an AVM-related tumor with irregularly linked blood vessels.
- Angiography: A tiny tube (catheter) is placed into an artery in the groin and directed to the spinal cord during an angiography. To make the blood vessels in the spinal cord visible during X-ray imaging, dye is injected into them. Angiography is utilized to locate and characterize the blood vessels responsible for the AVM.
- Ultrasound: use sound waves to create images.
Treatment
The treatment for spinal AVM aims to lessen symptoms and prevent possible complications by using a combination of approaches. The choice of treatment is based on factors such as the size, location, and blood flow of the spinal AVM, the results of the neurological exam, and the patient’s overall health. The objective of the treatment is to reduce the risk of hemorrhage and halt or prevent the worsening of disability and other symptoms associated with spinal AVM.
- Medication: Painkillers may be used to ease symptoms including back pain and stiffness, but surgery may eventually be required for the majority of spinal AVMs.
- Surgery: Surgical removal is necessary to access the surrounding tissue in cases of spinal AVM. There are three different methods for removing AVMs in the spine:
- Conventional surgery: The operation involves making a skin incision to remove the AVM while ensuring that the spinal cord and adjacent structures are not damaged. Generally, surgery is performed on small AVMs located in easily accessible areas of the spinal cord.
- Endovascular embolization: Endovascular embolization is a radiologic procedure that aims to decrease the chances of hemorrhage and other complications related to spinal AVMs. A catheter is used to insert small particles of a gluelike substance into an artery in the spinal cord that is supplying blood to the AVM, which blocks the artery and reduces blood flow into the AVM but does not destroy it permanently. Doctors may suggest endovascular embolization before other types of surgery to lessen the risk of bleeding during surgery or to shrink the AVM to enhance the surgery’s efficacy.
- Radiosurgery: Involves the application of focused radiation directly to the arteriovenous malformation (AVM) to obliterate its blood vessels. Gradually, the affected blood vessels disintegrate and shut off. This technique is typically employed to manage unruptured AVMs that are small in size.
The medical team discusses the advantages and disadvantages of AVM removal surgery with the patient. Since the AVM is located close to the spinal cord, spinal AVM surgery is a technically demanding and complex procedure that should be performed only by an experienced neurosurgeon.
