Embolization Treatment for Arteriovenous Malformations (AVMs) | Vascular Neurology of Southern California
The arteries are responsible for transporting oxygen-rich blood from the heart to the brain. As the blood flows, the arteries slow the blood by passing it through a series of progressively smaller networks of blood vessels, which end with the smallest blood vessels known as capillaries. Veins, on the other hand, carry the oxygen-depleted blood back to the lungs and heart.
A brain AVM (also known as an arteriovenous malformation) is a tangle of abnormal blood vessels connecting arteries and veins that disrupts this vital process. AVMs lack this supporting network of smaller blood vessels and capillaries and, instead, cause blood from the arteries to flow quickly to the veins, thus bypassing the surrounding tissues.
While AVMs occur most often in the brain or spine, they can develop anywhere in the body.
Although brain AVMs are rare and affect less than 1 percent of the population, and their cause is not clear, researchers believe they emerge during fetal development. People with them tend to be born with them, although they can occasionally form later in life. Rarely is there a tendency for AVMs to be genetically passed down within families.
Once diagnosed, the treatment of a brain AVM is often successful and prevents further complications, such as brain damage or stroke.
Dr. M. Asif Taqi is recognized as the leading neurointerventionalist in Southern California. As a quadruple-board certified neurointerventionalist, Dr. Taqi has extensive training and advanced expertise in treating brain AVMs. His first-hand understanding of the challenges presented by the neurovascular diagnosis of a brain AVM has earned him the reputation of being among California’s most respected neurointerventionalist.
Contact his team today to arrange your consultation in Thousand Oaks or West Hills, CA.
Symptoms, Causes, Complications, and Risk Factors of an AVM
Before moving on to embolization treatment for arteriovenous malformations, let’s briefly consider the symptoms a patient might experience as well as the possible causes, complications, and risks associated with AVMs.
Some patients with brain AVMs may experience signs and symptoms, which could include headaches or seizures. On the other hand, AVMs may only be detected during a brain scan for another health issue or after blood vessels rupture and cause hemorrhaging within the brain.
Because the arteries and veins in an AVM lack a supporting network of smaller blood vessels and capillaries, it is thought that most brain AVMs emerge while a fetus is still developing inside the uterus.
With the pressure applied by an AVM on the walls of the affected arteries and veins, they may become thin and weak and rupture, causing bleeding into the brain. This rush of blood starves brain tissues of oxygen, resulting in stroke-like symptoms.
If an AVM doesn’t burst, it may become more prominent and displace or compress portions of the brain leading to brain damage when brain tissue pushes up against the skull (hydrocephalus).
While anyone can be born with a brain AVM, being male or from a family with a history of AVMs can add to the risk of experiencing the condition.
What Are the Options for Treating AVMs?
Apart from embolization as described below, there are two other commonly applied surgical options for treating AVMs:
Generally known as resection, this option may be chosen if the brain AVM has hemorrhaged or is located in an area that can easily be reached via conventional brain surgery. Resection is usually performed when the AVM can be removed with little risk of hemorrhage or seizures.
Should an AVM be located in a deep region of the brain or carry a higher risk of complications, embolization, described below, might be the preferred treatment.
Mostly appropriate for small AVMs, this radiosurgery uses precisely focused radiation without an incision. SRS directs highly targeted beams of radiation at the AVM. As a result, the blood vessels become damaged, thus causing scarring with the blood vessels clotting off over some time.
What Is an AVM Endovascular Embolization?
Embolization treatment of an AVM is also known as Embolotherapy or Endovascular therapy. During the embolization, the patient typically remains conscious and is made comfortable with the help of the anesthesia team.
In some large brain AVMs, endovascular embolization may be used to reduce stroke-like symptoms by redirecting the blood flow back into healthy brain tissue.
Endovascular embolization is recognized as being less invasive than traditional surgery. While it may be performed as a standalone procedure, it is also frequently used prior to other surgical treatments to make those treatments safer by reducing the size of the AVM and the likelihood of bleeding.
By using X-ray imaging for guidance, a long, thin tube (catheter) is guided up the femoral artery in the groin into the area to be treated. Once in position, the catheter is moved into one of the arteries feeding blood into the AVM. An embolizing agent in the form of small particles, a glue-like substance, or some other material, is injected to block the artery and reduce blood flow into the AVM.
This embolizing agent rapidly hardens as it is injected into the AVM and results in the blocking of the blood flow through the AVM. When the blood flow passing through the AVM stops, there is no further risk of bleeding. It may be required for larger AVMs for the embolization to be repeated in stages where portions of the AVM are progressively blocked off. Until the entire AVM is completely closed off, there is still a risk of bleeding.
Throughout the process, the neurological team assesses the progress and once complete, a permanent agent is injected into the AVM, followed by the catheter being removed. The process is repeated for each vessel that feeds the AVM.
Patients usually spend the night in intensive care following the embolization procedure, where we will closely monitor them. Typically, patients can expect a three-night hospital stay for each embolization.
Patients treated by embolization will typically need to return for a follow-up angiogram or magnetic resonance angiogram (MRA). Usually, this is performed several months after the treatment. The results of these will show how much of the original AVM remains and if additional embolization is needed.
Depending on the severity of the AVM, patients usually require two or three embolizations at intervals of two to six weeks. Immediately after each discharge, they can resume their regular activities.
Mild headaches can be expected after the embolization, and this may be due to the blood vessels of the AVM clotting. Some nausea may result from some of the medicines that are prescribed.
Other possible side effects might include stroke-like symptoms such as weakness in one arm or leg, tingling, numbness, speech disturbances, and visual problems. The risk of AVM embolization remains regarding serious complications such as permanent stroke or death.
Can AVM embolization completely cure me?
Arteriovenous Malformation (AVM) embolization results in the reduced size of most AVMs. It is often recommended before the other forms of therapy and may not, in itself, be a complete cure.
What are the advantages of AVM Embolization?
- Embolization is very useful in reducing the size of the AVM in preparation for other forms of treatment.
- As an effective procedure to reduce the blood flow through the AVM just before surgery, an embolization facilitates the later removal of the AVM.
- AVM Embolization can be repeated and staged.
- No open surgical procedure is required.
- Short hospital stay.
What are the disadvantages of AVM embolization?
- The treatment can only be performed if the AVM consists of blood vessels that can be reached with the catheters.
- Multiple embolization sessions may be required.
- As a result of the treatment, there is a small chance of a stroke in about 1-3% of patients.
If you or a loved one have been given a diagnosis of an arteriovenous malformation (AVM), Southern California’s leading stroke prevention specialist and experienced neurointerventionalist, Dr. M. Asif Taqi, can help. Contact him or call (805) 242-4884 to schedule your appointment today.