What is an arteriovenous malformation (AVM)?
An arteriovenous malformation (AVM) is a congenital disorder (present from birth) characterized by a complex, tangled web of arteries and veins in which there is a short circuit and high pressure due to arterial blood flowing rapidly in the veins. An AVM may occur in the brain, brainstem or spinal cord. The most common symptoms of an AVM include hemorrhaging (bleeding), seizures, headaches and neurological problems such as paralysis or loss of speech, memory or vision. AVMs that bleed can lead to serious neurological problems and sometimes death. Still, some people have AVMs that never cause problems.
Why do AVMs form?
It’s not clear why AVMs form, but researchers believe that these tangles of vessels are present from birth. Several rare genetic diseases are associated with AVMs.
Is an AVM a serious health risk?
An AVM can cause hemorrhaging (bleeding) both into the brain and around the brain, seizures, headaches and neurological problems such as paralysis or loss of speech, memory or vision. AVMs that bleed can lead to serious neurological problems and sometimes death.
A wide range of studies are being conducted to explore the complex mechanisms of normal brain development. Knowledge gained from these studies provides the foundation for understanding how problems can occur, offering hope for new means to treat and prevent congenital disorders including AVMs.
Dural Fistulae/Dural arteriovenous malformations/Dural Shunts (DAVS)
Dural fistulae, dural AVMs and dural shunts (DAVS) all refer to a rare type of disease in which there is an abnormal short circuit between arteries and veins in the dura (leathery covering) over the brain and spine. While the cause of these diseases remains poorly understood, the way the disease causes problems for a patient has become clearer, mostly relating to the increasing pressure in the veins of the dura and over the brain itself. Dural shunts can cause several problems, including bleeding or ischemic strokes resulting from congested veins, or decreased or even ceased functioning of the brain or spinal cord from general venous congestion.
Are brain DAVS a serious health risk?
Dural shunts are complex in their effects, ranging from almost no risk to being seriously life threatening. Therefore, not all need to be treated aggressively. Some dural shunts have characteristics that make them more likely to rupture and cause strokes – at rates even higher than those of brain aneurysms. For this reason, dural shunts need to be thoroughly evaluated. Dural shunts with aggressive characteristics have a pattern of blood flow that puts a tremendous amount of flow into fragile, small veins on the surface of the brain, which can burst or create so much congestion that the brain no longer gets the blood flow it needs.
Vascular disorders of the spine
Vascular disorders of the spine are a rare type of disease in which there is an abnormal short-circuit between arteries and veins occurring either in or around the spinal cord. They may either be similar to AVMs, which cause bleeding problems, or to DAVS, which cause congestion that can back up blood flow and lead to the spinal cord ceasing to function.
Peripheral AVMs, Hemangiomata & Lymphangiovenous malformations
Peripheral AVMs, hemangiomata and lymphangiovenous malformations are unusual, diverse diseases of the peripheral vasculature that occur when there is either a short circuit between the arteries and veins (peripheral AVM) or when there is a malformation of the veins or lymphatic vessels, resulting in pooling of either blood or lymphatic fluid (hemangiomata and lymphatic and venous malformations).
Cleveland Clinic offers percutaneous sclerotherapy for these various diseases, in which an agent is injected via a needle that clots off the vessel and causes the lesion to scar and close.