Arteriovenous malformations
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Arteriovenous malformations (AVM) are an abnormal tangle of blood vessel that connect arteries and veins and impair normal blood flow and oxygen delivery. Although they can arise anywhere in your body, they mostly happen in your brain and spinal cord. Blood carrying oxygen from the heart to the brain is carried via arteries. The oxygen-depleted blood is then returned to the heart and lungs through veins.
The surrounding tissues may not receive adequate oxygen when an AVM interferes with this crucial process. Additionally, the abnormally tangled blood arteries that make up the AVM are prone to being damage and rupture, due to the pressure brought by the force of the blood flow. If the AVM ruptures in the brain, it may result in bleeding within brain (hemorrhage), which results in a stroke, or permanent brain damage.
AVMs have an unknown cause. They are rarely passed down among families. Once identified, a brain AVM can frequently be successfully treated to prevent complication.
Symptoms
Symptoms of an AVM may vary depending on where it is located. The most common site of AVM is found in the brain, which could results in brain hemorrhage. As a result of the surrounding tissue being interfere by AVMs, neurologic symptoms such as the following occur:
Brain AVM:
- Seizures
- Loss of consciousness.
- Headache, or dizziness.
- Muscle weakness, numbness, or tingling sensation.
- Paralysis.
- Nausea and vomiting.
- Impairment of balance, vision, memory and speech
- Mental confusion, hallucinations or dementia.
Spinal cord AVM:
- Back discomfort (abrupt onset and severe pain)
- Weakness in your legs, hips, and toes.
- Muscle weakness or paralysis due to affected nerves.
AVMs in other parts of the body: Depending on their size and the significance of the location, AVMs in other parts of the body (other than the brain and spine) may or may not cause symptoms. Typical general signs include:
- Shortness of breath or difficulty in breathing.
- Coughing up blood
- Abdominal pain.
- Lumps on the arms, legs, or trunk.
- Pain and swelling.
- Muscle weakness or paralysis.
- Tingling sensation or numbness.
- Open ulcers at the skin.
Congenital AVM: Symptoms of one type of AVM known as a vein of Galen defect which is a defect deep in the brain, start to show up at or soon after birth. An example of a sign is:
- Hydrocephalus: enlargement of the head due to fluid accumulate in the brain’s ventricles
- Swollen veins on the scalp
- Seizures
- Failure to thrive
- Congestive heart failure
If you have any of these symptoms, seek emergency medical attention immediately:
- Severe headaches
- Vision problems
- Seizure
- Weakness
- Changes in behavior or neurological function
Causes
AVMs develop when arteries and veins develop abnormal connections, although researchers are unsure what cause it to happen. Though most types are typically not inherited, some genetic modifications might be involved.
Risk factors
The following increases the risk to develop AVM are:
- Family history: At rare cases, it increases the risk to develop AVM if there are history of the condition within the family. However, most cases of AVM are not inherited. (1)
- Hereditary conditions: risk of AVM may be increased by some inherited disorders. These include Osler-Weber-Rendu syndrome and hereditary hemorrhagic telangiectasia (HHT).
Diagnosis
To diagnose an AVM, the doctor will be reviewing the patient’s history, perform a physical examination and several investigation to confirm an AVM.
AVM is frequently diagnosed using the following procedures:
- Cerebral angiography: This procedure, also known as an arteriography, involves injecting a contrast agent, a particular dye, into an artery. To make blood vessels more visible on X-rays, the dye enhances their structural details.
- Computerized tomography (CT): X-rays are used in CT scans to produce a more detailed images of the head, brain, or spinal cord that can help identify bleeding.
- Magnetic resonance imaging (MRI): A strong magnet and radio waves are used in an MRI to provide precise images of the tissues. Small changes in these tissues can be seen by an MRI.
- Magnetic resonance angiography (MRA): Is a type of magnetic resonance imaging (MRI) scan that uses to evaluate blood vessels and blood flow within the body.
- Doppler transcranial ultrasound: determines the rate of blood flow via your brain using sound waves.
Treatment
AVM treatment is based on the location of the abnormality, risk of AVM rupturing, your symptoms and general health. An AVM is occasionally checked for changes or problems using routine imaging procedures. An AVM’s requirement for therapy is determined by a number of variable factors, including:
- Bleeding
- Producing other symptoms besides bleeding
- Is located in a region of the brain that can be safely treated.
Medications
Medication can help with symptoms like back pain, headaches, and seizures.
Surgery
Surgery is the primary option of AVM treatment. If the risk of bleeding is high, the specialist might advise surgery. The AVM could be entirely eliminated through surgery. Surgical treatment is typically performed when an AVM is located in a location where removal by surgery can be accomplished with low risk of affecting healthy brain tissues.
- Endovascular embolization: is a type of surgery where specialist inserts a catheter into the arteries and then operates on the AVM. In order to restrict blood flow, a substance is injected to seal off portions of the AVM. To lessen the chance of complications, this could potentially be done prior to radiosurgery or brain surgery.
- Stereotactic radiosurgery: This method makes an AVM easier to be cured by using highly focused radiation beams that gradually shrink, scar, and constricting the blood flow to the AVM.
