Arteriovenous Malformations - Symptoms and Treatment

A cerebral arteriovenous malformation is a birth defect in which there is an abnormal connection between the arteries and veins in the brain. The arteries carry blood rich with oxygen from the lungs, and the veins carry blood back to the heart for recirculation. Each vessel is normally separate and travels in its own pathway. In an AVM, the blood vessels are tangled together and do not travel in their own path. Much like a small ball of string, the vessels are wrapped around each other. Most people with neurological AVMs experience few, if any, significant symptoms. The malformations tend to be discovered only incidentally, usually either at autopsy or during treatment for an unrelated disorder. But for about 12 percent of the affected population (about 36,000 of the estimated 300,000 Americans with AVMs), these abnormalities cause symptoms that vary greatly in severity. Seizures and headaches are the most generalized symptoms. AVMs also can cause a wide range of more specific neurological symptoms that vary from person to person, depending primarily upon the location of the AVM. Such symptoms may include muscle weakness or paralysis, loss of coordination, difficulties carrying out tasks that require planning, dizziness, visual disturbances, problems using or understanding language, abnormal sensations (such as numbness, tingling, or spontaneous pain), memory deficits, mental confusion, hallucinations, or dementia.

Arteriovenous malformations (AVMs) are defects of the circulatory system that are generally believed to arise during embryonic or fetal development or soon after birth. The genetic transmission patterns of AVM (if any) are unknown, and AVM is not generally thought to be an inherited disorder unless in the context of a specific hereditary syndrome . Normally, the arteries in the vascular system carry oxygen-rich blood at a relatively high pressure. Structurally, arteries divide and sub-divide repeatedly, eventually forming a sponge-like capillary bed . Blood moves through the capillaries, giving up oxygen and taking up waste products from the surrounding cells. Capillaries successively join together, one upon the other, to form the veins that carry blood away at a relatively low pressure. The heart acts to pump blood from the low pressure veins to the high pressure arteries. In the case of an AVM, there is an absence of capillaries in this "circuit." As a result, the vessels of an AVM have rather abnormal flow patterns that may be harmful, especially if a particular AVM has a high amount of blood flow or high pressures. This is a particularly serious problem in instances where AVMs involve parts of the central nervous system (the brain, spinal cord and their respective coverings, specifically the dura).

Causes of Arteriovenous Malformations

The common Causes of Arteriovenous Malformations :

• Most AVMs are not inherited with the exception of a condition called H.H.T. An AVM is not a cancer, and does not spread to other parts of the body.
• Cerebral arteriovenous malformations occurs in less than 1% of people. Although the condition is present at birth, symptoms may occur at any age. Hemorrhages occur most often in people aged 15-20, but can also occur later in life. Some patients harboring an AVM also have a cerebral aneurysm.
• In a small minority of cases, cerebral AVMs are associated with other inherited disorders, such as the Osler-Weber-Rendu syndrome (ie, hereditary hemorrhagic telangiectasia), Sturge-Weber disease, neurofibromatosis, and von Hippel-Lindau syndrome.
• The cause of cerebral arteriovenous malformation (AVM) is unknown. The condition occurs when, in the brain, one or more blood vessels develop in which the arteries connect directly to the veins, without having the normal capillaries between them.
• Arteriovenous malformations vary in their size and location within the brain.

Symptoms of Arteriovenous Malformations

Some common Symptoms of Arteriovenous Malformations :

• Muscle weakness.
• Dizziness.
• Difficulty speaking or understanding language.
• Sudden, severe back pain.
• Memory loss .
• Difficulty thinking or mental confusion.
• Loss of sensations (hearing, taste, or touch).
• Visual disturbances.

Treatment of Arteriovenous Malformations

• A narrow x-ray beam is focused on the AVM such that a high dose is concentrated on the AVM with a much lower dose delivered to the rest of the brain.
• Treatment of AVM may involve surgery to remove the bundle of vessels.
• The definitive treatment for AVMs is either surgery or focused irradiation therapy.
• The patient may not be able to eat at first, so an intravenous line will be inserted into a vein to give plenty of fluid. Medications for pain, sedation and a stool softener likely will be given.
• Arteriovenous Malformations is important to get plenty of rest, so the patient may be in a darkened room and should try to keep as quiet and comfortable as possible.
• Radiosurgery or Stereotactic Radiotherapy.