Cerebral arteriovenous malformation (AVM) often causes no signs or symptoms until the AVM ruptures, resulting in bleeding in the brain.

A cerebral arteriovenous malformation is an abnormal connection between arteries and veins in the brain that's present at birth (congenital). Arteriovenous malformations, which appear as tangles of normal or dilated blood vessels, can occur in any part of the brain. The cause isn't clear.

In most people with arteriovenous malformation bleeding is the first symptom, but some may experience:

• seizures
• a whooshing sound (bruit) that can be heard on examination of the skull with a stethoscope
• pulsing noise in the head (pulsatile tinnitus)
• headache
• progressive weakness or numbness.

When bleeding into the brain occurs, signs and symptom can be similar to a stroke and may include:

• sudden, severe headache
• weakness or numbness
• vision loss
• difficulty speaking
• inability to understand others
• severe unsteadiness.

A bleeding AVM is life-threatening and requires emergency medical attention.