AVM Stroke: Can an Arteriovenous Malformation Cause a Stroke?

An AVM stroke can be a life-threatening emergency. The effects and treatment depend on whether the AVM has bled, where it is located, its size and vascular anatomy, and how much brain tissue has been affected. Prompt diagnosis and treatment are important because bleeding can cause permanent brain injury or death.

This guide explains how an AVM can cause a stroke, the symptoms of an AVM hemorrhage, how doctors diagnose and treat AVMs, and what to expect during AVM stroke recovery.

An AVM is an abnormal connection between arteries and veins. Under normal circumstances, arteries carry oxygen-rich blood toward the brain. The blood then passes through tiny vessels called capillaries before entering the veins and returning to the heart.

Capillaries help slow blood flow and allow oxygen and nutrients to reach surrounding brain tissue.

With an AVM, this normal capillary network is absent. Instead, blood flows directly from arteries into veins through a tangled collection of abnormal vessels. The unusually rapid flow can place stress on the vessel walls and affect oxygen delivery to nearby brain tissue.

Brain AVMs are relatively rare. Some are discovered incidentally during brain imaging, whereas others are identified after symptoms such as seizures, headaches, neurological problems, or bleeding have occurred.

The exact cause of most brain AVMs is not known. Many are believed to form during early vascular development, although they are sometimes associated with an inherited condition such as hereditary hemorrhagic telangiectasia.

A stroke occurs when part of the brain is damaged because its blood supply is interrupted or a blood vessel bleeds.

There are 2 major types:

• Ischemic stroke: A blood vessel supplying the brain becomes blocked, reducing or stopping blood flow.
• Hemorrhagic stroke: A blood vessel ruptures and blood leaks into the brain or the surrounding spaces.

AVMs are particularly associated with hemorrhagic stroke. If the abnormal vessels rupture, blood can accumulate within brain tissue or in the spaces surrounding the brain. The blood can damage nearby cells and increase pressure inside the skull.

In some cases, an AVM can also interfere with normal blood flow and contribute to neurological problems that resemble stroke symptoms.

Yes. As outlined above, an AVM in the brain can cause a stroke, most commonly by rupturing and hemorrhaging.

When an AVM ruptures, blood can enter the brain tissue, producing an intracerebral hemorrhage. It can also bleed into the subarachnoid space surrounding the brain. Either type of bleeding can cause sudden neurological symptoms and requires emergency medical attention.

Rupturing is not the only way an AVM can affect the brain. The abnormal blood flow associated with some AVMs can reduce oxygen delivery to surrounding tissue or place pressure on nearby brain structures, which can contribute to neurological symptoms including weakness, numbness, seizures, headaches, speech difficulties, or problems with coordination.

Hemorrhagic stroke from an AVM occurs when one or more abnormal vessels rupture.

The bleeding itself can injure brain cells. In addition, accumulated blood can compress surrounding tissue and increase pressure within the skull. Depending on where the hemorrhage occurs, a person can develop problems with movement, sensation, speech, vision, balance, consciousness, or other neurological functions.

The annual risk of bleeding from an untreated brain AVM is often estimated at about 2% to 3%, although the risk varies considerably among individuals. Previous hemorrhage is an important risk factor for future bleeding. Other characteristics, such as certain patterns of venous drainage and the AVM’s location and vascular anatomy, can also influence risk.

An AVM is associated much more strongly with hemorrhagic stroke than with conventional ischemic stroke.

However, abnormal blood flow through an AVM can sometimes affect the blood supply to surrounding brain tissue, which, in some patients, can contribute to reduced oxygen delivery and neurological deficits that may resemble stroke symptoms.

Because the symptoms of ischemic and hemorrhagic stroke can overlap, imaging is essential. Doctors cannot reliably determine the type or cause of a stroke from symptoms alone.

Symptoms of an AVM stroke can develop suddenly when the malformation bleeds. Possible symptoms include the following:

• Sudden, severe headache
• Nausea or vomiting
• Weakness or numbness, particularly on one side of the body
• Difficulty speaking or understanding speech
• Vision changes or vision loss
• Difficulty walking or maintaining balance
• Confusion or altered consciousness
• Seizures
• Loss of consciousness
• Problems with coordination or movement

Some people with a brain AVM experience symptoms before a hemorrhage, such as recurrent headaches or seizures. Others have no warning symptoms and discover the AVM only after it bleeds or during brain imaging performed for another reason.

Any of the above symptoms should always be treated as a medical emergency.

An AVM contains abnormal vessels that do not have the same structure as normal arteries and veins. In them, blood flows directly from arteries into veins, bypassing the normal capillary network. This unusual circulation can place significant pressure and stress on the abnormal vessels. Over time, weakened vessels may rupture and cause bleeding.

Several characteristics can affect the likelihood of hemorrhage:

• Whether the AVM has bled previously
• Its location in the brain
• Its size and vascular structure
• The pattern of venous drainage
• Whether an associated aneurysm is present
• Other individual characteristics identified through angiography and imaging

Not every AVM is at the same risk of bleeding. Research has identified previous hemorrhage as one of the most consistent predictors of future bleeding, whereas other risk factors vary among studies and patient groups.

When a person arrives at the hospital with possible stroke symptoms, doctors first need to determine whether the brain is bleeding and, if so, identify the cause.

A CT scan is often used quickly to detect acute bleeding. MRI can provide more detailed information about brain tissue and the AVM. Vascular imaging, including CT angiography, magnetic resonance angiography, and/or conventional cerebral angiography, might then be used to define the abnormal blood vessels.

A cerebral angiogram is particularly valuable when doctors are planning treatment because it can show the arteries feeding the AVM, the abnormal vascular tangle, and the veins draining it.

The medical team might also evaluate the location and size of the hemorrhage, pressure within the skull, neurological function, and other factors that could affect treatment.

An AVM hemorrhage requires immediate hospital care, often in a specialized stroke or neurosurgical center.

The initial goal is to stabilize the patient, control complications from the bleeding, protect the brain, and determine whether and when the AVM itself should be treated.

Emergency care may include:

• Supporting breathing and circulation
• Monitoring neurological status
• Managing blood pressure appropriately
• Treating seizures when they occur
• Monitoring and controlling pressure inside the skull
• Treating complications associated with the hemorrhage

The specific approach depends on the location and severity of the bleeding and the patient’s overall condition.

Not every brain hemorrhage requires immediate removal of the blood. Treatment depends on the size and location of the hemorrhage, the degree of pressure on the brain, the patient’s neurological condition, and the underlying AVM.

In selected cases, neurosurgery may be necessary to remove blood, relieve pressure, or address the AVM itself.

Doctors must balance the urgency of treating the hemorrhage against the risks of operating on an abnormal blood-vessel network. A ruptured AVM may ultimately require definitive treatment to reduce the risk of another hemorrhage.

During the acute phase, clinicians focus on limiting secondary brain injury, which can involve careful management of blood pressure, oxygenation, body temperature, seizures, fluid balance, and intracranial pressure. The patient may be monitored closely in an intensive care setting when the hemorrhage is severe.

Once the patient is stabilized, specialists determine whether the AVM should be removed, blocked, treated with focused radiation, or monitored.

The goal of definitive AVM treatment is generally to eliminate or significantly reduce the abnormal vascular connection and prevent future bleeding. However, treatment is not automatically appropriate for every AVM.

Doctors consider the patient’s age and health, whether the AVM has previously bled, its size and location, its vascular anatomy, and the risks of treatment compared with the risk of leaving it untreated.

Microsurgery involves opening the skull and surgically removing the AVM. This surgery might be an option when the AVM is relatively accessible and can be removed without causing unacceptable damage to important brain structures. For appropriately selected AVMs, surgery can provide immediate removal of the abnormal vessels.

However, brain surgery carries risks, including bleeding, infection, seizures, stroke, neurological deficits, and other complications. The decision requires detailed imaging and evaluation by an experienced cerebrovascular neurosurgical team.

Endovascular embolization is a treatment performed from inside the blood vessels. A specialist guides a catheter through the vascular system toward vessels feeding the AVM. Materials are then used to reduce or block blood flow through selected abnormal vessels.

Embolization is sometimes used as a stand-alone treatment, but it is also frequently used as part of a broader treatment strategy. For example, it can reduce the size or blood flow of an AVM before microsurgical removal or radiosurgery.

Whether embolization can eliminate an AVM depends on its anatomy. In some cases, additional treatment is required.

Stereotactic radiosurgery uses highly focused radiation directed at the AVM. Unlike conventional surgery, it does not require a large surgical incision. The radiation damages the abnormal blood vessels, which gradually scar and close over time.

Radiosurgery might be considered for smaller AVMs or AVMs located in an area in which traditional surgery would be particularly risky. The AVM does not disappear immediately; closure can take months or, in some cases, several years. During this period, the risk of hemorrhage could persist.

Some patients require a combination of treatments, such as embolization followed by surgery or radiosurgery.

AVM stroke recovery varies substantially from person to person. Some people recover relatively well after a small hemorrhage, while others experience long-term disabilities after a major brain bleed.

Recovery depends on several factors:

• Amount of bleeding
• Location of the hemorrhage
• Areas of the brain that were injured
• Patient’s age and general health
• How quickly emergency treatment was provided
• Any complications such as seizures or increased intracranial pressure
• Extent of neurological impairment after the stroke

Rehabilitation might begin in the hospital once the patient is medically stable.

Depending on the individual’s needs, rehabilitation can include the following:

• Physical therapy to improve strength, mobility, balance, and coordination
• Occupational therapy to improve daily activities and independence
• Speech and language therapy for communication and swallowing difficulties
• Cognitive rehabilitation for memory, attention, planning, or other thinking problems
• Psychological support for emotional and behavioral changes after brain injury

Recovery can continue for months or longer. Progress is often gradual, and the amount of improvement cannot be predicted from the diagnosis alone.

The AVM itself also needs follow-up. If treatment has not eliminated the malformation, additional treatment or monitoring may be necessary.

An AVM itself cannot always be prevented because the exact cause of most brain AVMs is unknown.

However, once an AVM has been diagnosed, doctors can evaluate whether treatment could reduce the risk of future hemorrhage. Treatment decisions are individualized because interventions themselves carry risks.

People diagnosed with an AVM should follow their specialist’s recommendations for imaging and follow-up. Managing overall cardiovascular health, taking prescribed medications correctly, and following medical advice are also important.

No home treatment can repair a brain AVM. People should not delay specialist evaluation because they feel well; some AVMs cause few or no symptoms before bleeding occurs.

Seek emergency medical care immediately if you or someone else develops symptoms that could indicate an AVM stroke or another type of stroke.

Warning signs include:

• Sudden severe headache
• Sudden weakness or numbness
• Facial drooping
• Difficulty speaking or understanding speech
• Sudden vision problems
• Sudden loss of balance or coordination
• A seizure
• Confusion
• Loss of consciousness
• Sudden nausea or vomiting accompanied by neurological symptoms

Do not wait to see whether symptoms improve. Brain hemorrhage is a medical emergency, and rapid evaluation can help doctors identify the cause and begin appropriate treatment.

It is particularly important to seek immediate care for a person known to have a brain AVM who develops a sudden severe headache, seizure, weakness, confusion, or other abrupt neurological symptoms.

When an arteriovenous malformation (AVM) causes bleeding or stroke, timely evaluation by an experienced cerebrovascular neurosurgeon is essential. Dr. Aaron Cohen-Gadol is a board-certified neurosurgeon with expertise in the surgical treatment of complex brain vascular conditions, including cerebral AVMs. He evaluates each patient individually to determine the AVM’s size, location, bleeding risk, and relationship to critical areas of the brain. Based on these factors, he can help patients understand whether microsurgical resection or another treatment approach may be appropriate.

There is no single survival rate that applies to every AVM stroke. Prognosis depends on several factors including the amount and location of bleeding, neurological status, age and general health, complications, and how quickly treatment is provided.

A hemorrhagic stroke caused by an AVM can be life-threatening, and the American Stroke Association notes that the risk of death from an AVM-related bleed varies depending on the circumstances of the hemorrhage.

For an individual patient, the treating medical team is in the best position to estimate prognosis, because they can evaluate the patient’s imaging and neurological condition.

An AVM most commonly causes a hemorrhagic stroke, which happens when the abnormal blood vessels rupture and bleed into the brain or the surrounding spaces. AVMs can also produce neurological symptoms without an obvious hemorrhage because abnormal blood flow can affect oxygen delivery or nearby brain structures.

No. An AVM and a brain aneurysm are different types of blood-vessel abnormalities. An AVM is a tangled network of abnormal vessels connecting arteries and veins without the normal capillary network; an aneurysm is a localized bulge or weakened area in the wall of a blood vessel.

However, an AVM can sometimes be associated with an aneurysm, which may affect the overall risk assessment and treatment plan.

There is no standard recovery time for an AVM stroke. Some people can make significant improvements over weeks or months, while others require longer-term rehabilitation and may have permanent neurological problems.

Recovery depends largely on the severity and location of the hemorrhage, the brain functions affected, complications, and the person’s response to rehabilitation.

Even after the initial hospitalization, recovery might need to continue for many months. Follow-up care is also important for determining if the AVM has been treated and if additional treatment or monitoring is necessary.

A brain AVM can cause an AVM stroke, most commonly when the abnormal blood vessels rupture and produce a hemorrhagic stroke. An AVM can also interfere with normal blood flow and cause other neurological symptoms.

The symptoms of an AVM hemorrhage can appear suddenly and include severe headache, weakness, numbness, speech or vision problems, seizures, confusion, and/or loss of consciousness. Because these symptoms can indicate life-threatening brain bleeding, emergency medical evaluation is essential.

Diagnosis typically involves CT or MRI along with vascular imaging to understand the AVM’s structure. Treatment might include microsurgical removal, endovascular embolization, stereotactic radiosurgery, or a combination of approaches. For some patients, careful monitoring alone could be appropriate when the risks of intervention outweigh the expected benefits.

AVM stroke recovery times also vary widely. Rehabilitation can help people regain movement, communication, cognitive abilities, and independence after a brain hemorrhage, but the outcome depends on the severity and location of the injury and the individual’s response to treatment.

Anyone diagnosed with a brain AVM should discuss their individual hemorrhage risk and treatment options with a neurologist, neurosurgeon, or other cerebrovascular specialist. The best approach depends on the specific anatomy of the AVM rather than on a single treatment being appropriate for everyone.