A healthy young adult suddenly notices that one hand feels weak and speech has become slurred. The symptoms improve within minutes, so it is tempting to blame fatigue. Brain imaging, however, may reveal an abnormal cluster of blood vessels. A brain arteriovenous malformation, or AVM, is uncommon, but it can first appear as a seizure, a stroke-like episode, or bleeding in the brain. Recognizing the warning signs early can protect both life and brain function.

What is a brain AVM?

In normal circulation, arteries carry oxygen-rich blood into a fine capillary network before the blood returns through veins. A brain AVM is an abnormal tangle in which arteries connect directly to veins and bypass that capillary cushion. The fast flow can place stress on thinner venous walls, while altered circulation may affect nearby brain tissue. An AVM is not a brain tumor and does not turn into cancer; in most people, the precise cause is unknown.[1,2]

Four warning patterns that deserve attention

Some AVMs remain silent for years and are discovered on a scan performed for another reason. In other people, the first sign is a brain hemorrhage. Symptoms vary with the location and size of the AVM and with whether bleeding has occurred.[1,2]

A sudden, severe headache: A headache unlike any previous headache, especially with vomiting, marked drowsiness, confusion, or loss of consciousness, may signal intracranial bleeding.[2]

A first seizure: A seizure may involve generalized shaking, but it can also appear as staring, loss of awareness, or repeated jerking of one side of the body.[2]

Stroke-like symptoms: Sudden facial droop, one-sided weakness or numbness, difficulty speaking, visual change, or loss of balance requires urgent assessment, even if it improves after a few minutes.[2]

Headache with neurological symptoms: Most headaches are not caused by an AVM. Concern rises when the headache pattern changes abruptly or is accompanied by weakness, altered sensation, or a seizure.[2]

What should a family member do?

Call emergency medical services immediately for a sudden severe headache, a first seizure, a change in consciousness, or new stroke-like symptoms. Note the time the person was last known to be well and when symptoms began. Do not drive the person yourself, offer food, water, or medication, or wait for symptoms to disappear. During a seizure, clear nearby hazards and protect the head. When the jerking stops, gently place the person on one side. Do not restrain the limbs and never put an object in the mouth.[4]

How is an AVM identified?

In an emergency, a computed tomography (CT) scan is often used first to look for bleeding. Magnetic resonance imaging (MRI) can show the AVM and its relationship to nearby brain tissue in greater detail. Cerebral angiography maps the feeding arteries, the abnormal vessel cluster, and the draining veins and is important when treatment is being planned. The appropriate tests depend on the clinical situation; not every person with a headache needs a full vascular workup.[1,3]

Does every AVM require open surgery?

No. The goal is to reduce the risk of future bleeding while preserving normal brain function. A multidisciplinary team weighs previous hemorrhage, symptoms, age and general health, AVM size and location, and the pattern of feeding and draining vessels. One treatment or a combination may be recommended.[1,3]

Microsurgical removal: The abnormal vessel cluster is removed through an operation. This may be suitable for selected AVMs that are relatively small, superficial, and safely accessible.[1,3]

Endovascular embolization: A thin catheter is guided through an artery from the wrist or groin to the AVM. An embolic material is delivered to reduce abnormal blood flow. Embolization is often used before another treatment, although its role varies by anatomy.[1,3]

Stereotactic radiosurgery: Precisely focused radiation is directed at the AVM without an open incision. The vessels close gradually, so follow-up remains necessary during the interval before obliteration.[1,3]

Observation and symptom control: When intervention may carry greater risk, careful imaging follow-up and medication for seizures or headaches may be the preferred plan.[1,3]

Frequently asked questions

Q: Does frequent headache mean that I have a brain AVM?

A: No. Headaches have many causes, and their location or intensity alone cannot diagnose an AVM. A sudden severe headache or a headache with a new neurological problem needs urgent evaluation.[2]

Q: Can an AVM be ignored if it causes no symptoms?

A: It should not be ignored, but immediate treatment is not automatic. For an unruptured AVM, clinicians compare the expected natural history with the risks and benefits of intervention, then make an individualized decision with the patient.[1,3]

An integrated treatment approach at Far Eastern Memorial Hospital

At Far Eastern Memorial Hospital, neurosurgery, neurovascular intervention, and radiation oncology can assess each vascular pattern and consider microsurgery, endovascular embolization, stereotactic radiosurgery, or a combined plan. During complex cerebrovascular operations, intraoperative fluorescence angiography may be used to visualize blood flow and help confirm how the abnormal vessels have been addressed.[5]