An arteriovenous malformation is a vascular anomaly characterized by an abnormal link between arteries and veins within the body and is often a congenital disorder. Though it can involve arteries and veins of any part of the body, it occurs mostly in the brain and spinal cord. AVM can also occur due to hereditary hemorrhagic telangiectasia.
Prevalence and Course of AVM
The prevalence of this disease is not high; with the rate being calculated around 0.01%. This rate can however range from 0.01 to 0.51%. This condition is long-standing since its symptoms are non-specific. This means the disease progresses while the patient is asymptomatic or shows no symptoms. With the invention of imaging technologies, it is possible to detect AVM earlier on. An earlier detection allows for a shortened duration of the illness.
Description of AVM
AVM was first identified by the work of Luschka, Virchow and Emmanuel in the 1800’s. With normal arteriovenous functioning, the blood flows easily without any hurdle from the arteries to the veins. Normal arteries are meant to carry oxygenated blood while veins deoxygenated blood.
When arteriovenous malformations occur, the normal process is altered markedly; the dampening effects of the capillaries are lost and results in the formation of a tangled mass called a nidus which is devoid of capillaries. Capillaries are responsible for the removal of carbon dioxide and for the delivery of nutrients to cells. This function is diminished when the arteries are malformed. Arteries become thin and fragile and a whooshing type of sound from them can be heard through a stethoscope. This type of sound is called a bruit.
Symptoms of Arteriovenous Malformation
AVM is an asymptomatic disease, meaning patients experience no symptoms. It becomes evident on a post mortem or as an incidental finding in the search of other diseases. The symptoms of AVM include loss of coordination of body movement, movement difficulties, and speech problems, loss of memory, dizziness, recurrent bleeding, visual disturbances, numbness and tingling type of sensations. When intracranial haemorrhaging occurs, symptoms of a headache and seizures occur. Neurologic deficit is also common.
When To See a Doctor
It is essential to see a doctor as soon as the symptoms occur; even though the symptoms themselves may not show in AVM, it is advisable to have any possible symptoms checked out as soon as possible.
Diagnosing AVM
As AVM can develop in different parts of the body, the whole body should be examined in order to detect the condition.
Computed tomography angiography (CTA) is the best method to visualize the condition. Computed tomography angiography checks for structural abnormalities of arteriovenous malformations and also the presence or absence of aneurysms, blockages of venous outflow and even patterns of venous drainage. AVM can also be detected with the use of computerized tomography (CT scan), catheter angiography, magnetic resonance angiography (MRA) or magnetic resonance imaging (MRI).
Treatment for AVM
In cases of AVM in the brain, the risk for haemorrhaging is high. AVM needs to be addressed by surgical manipulation. Radiosurgery or embolization may be performed. In some patients both can be performed. A complete eradication of the arteriovenous malformation is the aim of treatment, as partial elimination appears to offer little or no safety from haemorrhages. Other treatment for AVM includes symptomatic treatments.
Risk Factors
AVM increases the chance of developing a further disease. It is also genetic with a family history of AVM and a history of bleeding or recurrent types predisposing one to developing AVM.
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