Overview of Arteriovenous Malformation Treatment
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Arteriovenous malformations (AVMs) are abnormal artery to vein connections resulting in a tangle of blood vessels. Most individuals do not experience symptoms until an AVM ruptures. Fortunately, AVMs can be cured primarily through surgery, radiosurgery, endovascular embolization or a combination of the above.
The decision of whether to treat an AVM is complicated and based on several factors. In this article, we provide an overview of the treatment options available. Visit the links provided to read more detailed information about each treatment option.
AVM Treatment Options
Fortunately, AVMs can be cured with surgery. Surgery involves complete removal of the AVM and rerouting of blood flow to normal vessels. AVM surgery is one of the most challenging operations in neurosurgery and requires a neurosurgeon with extensive experience and technical expertise.
Endovascular embolization and radiosurgery are two other treatment modalities that can also be used to cure an AVM, though they have a lower cure rate than surgery. Typically, endovascular embolization is used in combination with surgery to help facilitate easier and complete surgical removal. Radiosurgery may be used if surgery is deemed too risky, though has a treatment latency period of several years before the AVM can be cured or eliminated.
Endovascular embolization is a minimally invasive procedure that involves inserting a thin flexible tube (catheter) in a blood vessel at the arm or leg, then advancing it up to the blood vessels in the brain. Once directed to a vessel of the AVM, the operator injects a glue that rapidly solidifies and can block blood flow to the AVM.
In radiosurgery, targeted beams of radiation are aimed at the AVM with the goal of causing scarring over time that will eventually block off all blood flow to the AVM, effectively removing it from normal circulation. This process can take several years. Until full closure two to three years after treatment, the AVM is still at risk for rupture.
There are no medications to treat an AVM directly, though pain medications and anti-seizure medications may be used to manage symptoms as needed. Research on potential medications is underway, though currently surgery, endovascular embolization, and radiosurgery will be the main forms of treatment.
When to Treat an AVM?
The decision to treat an AVM or simply observe it over time depends on whether the AVM was discovered before or after rupture, and whether symptoms are present. Described below are the different possible situations.
AVM Found Incidentally Before Rupture
Determining whether to treat an AVM found incidentally requires knowledge about the risk of rupture when the AVM goes untreated. Every year, an AVM is estimated to have a 2 – 4% risk of rupture. Cumulatively, the lifetime rupture rate can be estimated using the formula 105 – patient age. A younger patient has a larger risk of AVM rupture over the course of their lifetime when compared to an older patient.
However, this convenient formula does not consider other factors specific to the AVM that may increase your risk for rupture. AVMs with associated aneurysms and an AVM located deeper within the brain may have an elevated annual risk for rupture. Thus, curative treatment such as surgery or radiosurgery may be more favorable in these cases.
The risks of AVM rupture must be weighed against the risks of developing lasting or permanent neurological deficits due to and after treatment. Smaller AVMs that are located closer to the surface of the brain are easier to remove and are associated with the best outcomes after surgery. Treatment is thus most favorable for cases where the patient is young, and the AVM is small and superficial.
AVM Causing Symptoms Before Rupture
In addition to the considerations described above, a patient experiencing symptoms attributed to the AVM itself (without rupture) may have more reason to undergo treatment. These symptoms (excluding rupture and associated severe headaches), may be chronic pulsatile headaches, weakness, or numbness, and/or other neurological symptoms.
If an AVM is too large or too deep within the brain to be safely surgically removed, endovascular embolization or radiosurgery may be attempted. In palliative endovascular embolization, glue is injected into the largest of the abnormal vessels to try to limit blood flow to the AVM as much as possible.
A ruptured AVM is a life-threatening condition that requires immediate medical attention. Individuals with a ruptured AVM may experience a sudden and severe headache, loss of consciousness, and neurologic changes due to subarachnoid hemorrhage or more frequently a blood clot in the brain (intracerebral hemorrhage). Although most individuals survive, 30 – 50% of patients may be left with mild to severe neurologic impairments and require rehabilitation.
Upon rupture, the AVM bleeds but does not go away on its own. In fact, after rupture, the risk of another rupture is increased and a discussion of surgery, endovascular embolization, and/or radiosurgery ensues. Due to the elevated risk of another bleed, interventional treatment becomes more favorable, though the risks of treatment in the context of your overall health and presence of other medical conditions must still be considered.
A patient’s age, health, and AVM characteristics (including ruptured or not) all play a role in determining whether treatment is appropriate, and what exactly the treatment will entail. The risks of treatment must be weighed against the risk of AVM rupture, with each being influenced by other factors such as the surgeon’s experience and expertise, and AVM size and location. This can be a lot to digest. A comprehensive evaluation and discussion with a neurosurgeon of appropriate expertise are critical to plan the best path forward.
- AVM treatment options include surgery, endovascular embolization, and/or radiosurgery.
- Surgery provides the highest cure rates and may be used with other treatment options to facilitate safe and complete AVM removal.
- Determining the appropriate treatment plan requires consideration of many factors related to the risk of rupture without treatment, and risk of poor outcomes with treatment.