Arteriovenous Fistulas
An arteriovenous fistula (AVF) is an abnormal connection between an artery and a vein that allows blood to flow directly from the high-pressure arterial system into the venous system without passing through the normal network of small blood vessels called capillaries.
Arteriovenous fistulas can occur in different areas of the body, including the brain and spinal cord. Dural arteriovenous fistulas (dAVFs) are a type of AVF that develop in the protective coverings of the brain or spinal cord, called the dura. These abnormal connections can affect normal blood flow and may vary in their symptoms and effects depending on their location and characteristics.
Some arteriovenous fistulas may be discovered during imaging performed for another reason, while others may cause neurological symptoms or other complications.
Common Symptoms
Symptoms of an arteriovenous fistula can vary depending on its location, blood flow pattern, and whether surrounding tissues are affected.
Possible symptoms may include:
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Headaches
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Pulsing or whooshing sounds in the ears (pulsatile tinnitus)
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Vision changes
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Seizures
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Numbness, weakness, or changes in sensation
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Difficulty with balance or coordination
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Changes in memory, thinking, or other neurological functions
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Back pain or weakness in the legs (in some spinal AVFs)
Some arteriovenous fistulas may not cause noticeable symptoms and may be found during diagnostic imaging.
Risk Factors and Causes
The exact cause of many arteriovenous fistulas is not always known. Unlike many arteriovenous malformations (AVMs), some dural arteriovenous fistulas may develop later in life.
Potential factors associated with arteriovenous fistulas may include:
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Abnormal blood vessel development: Some AVFs may be related to differences in how blood vessels form.
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Previous blood clots: Certain dural AVFs may be associated with changes in venous blood flow, including venous sinus thrombosis.
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Head injury or trauma: Trauma may contribute to the development of some fistulas.
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Previous surgery or procedures: Certain medical procedures may affect blood vessels and contribute to abnormal connections.
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Age-related vascular changes: Some types of AVFs are more commonly identified in adults.
The development of an arteriovenous fistula is not typically related to lifestyle choices, and many occur without a clear cause.
How Can Arteriovenous Fistulas Be Treated?
Treatment for an arteriovenous fistula depends on factors such as its location, blood flow characteristics, symptoms, and the surrounding structures involved.
Treatment approaches may include:
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Monitoring and imaging follow-up: Some fistulas may be evaluated over time depending on their characteristics.
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Endovascular embolization: A minimally invasive procedure that uses specialized materials to block abnormal blood flow through the fistula.
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Microsurgical treatment: In some cases, surgery may be performed to disconnect or remove the abnormal connection.
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Stereotactic radiosurgery: A focused radiation treatment that may be considered for certain vascular abnormalities.
A specialist can review imaging studies and evaluate the specific characteristics of an arteriovenous fistula to discuss available treatment approaches.