Symptoms of AVMs

AVMs often do not cause any clinical problems until they rupture. AVMs can cause symptoms either by bleeding (rupturing), pressing on the brain or spinal cord, or by reducing the amount of oxygen reaching the brain tissue.

Symptoms might include the following:

Headaches

Some people with AVMs experience headaches, while others never do. When headaches occur, they are often similar to migraines and can sometimes happen at the back of the head. Having headaches does not mean that the AVM is more likely to bleed. The risk of bleeding depends mainly on features seen on brain scans, not on whether headaches are present.

Treatment for an AVM is usually focused on reducing the risk of bleeding. If headaches remain the main issue, they are often treated in the same way as other types of headache, with medicines and lifestyle measures tailored to the individual.

Bleeding

Brain AVMs may cause bleeding into the brain (haemorrhage), causing sudden, severe headaches, confusion, nausea, vomiting, and may lead to a loss of consciousness.

Seizures

Seizures are bursts of abnormal brain activity that can affect behaviour, movement, sensation, and awareness, ranging from brief staring to severe convulsions.

Focal seizures begin in one area of the brain and may or may not impair awareness, sometimes progressing to convulsions. Generalised seizures involve the whole brain, causing loss of consciousness, spasms, or convulsions, and include absence, tonic-clonic, atonic, and myoclonic types.

Convulsions are uncontrolled movements, often with stiffening, jerking, and loss of consciousness. In AVMs, seizures arise when the malformation disrupts normal electrical activity.

Neurological Symptoms

These depend on the location of the AVM and can include muscle weakness or paralysis in one part of the body, a loss of coordination (ataxia) that can lead to such problems as gait disturbances, difficulties carrying out tasks that require planning, memory deficits, dizziness, visual disturbances such as a loss of part of the visual field, difficulties with speech (dysarthria), and abnormal sensations such as numbness, tingling, or spontaneous pain (paresthesia or dysesthesia).