Arteriovenous Malformation

What is an arteriovenous malformation (AVM)?

An AVM is a tangled mesh of abnormal blood vessels directly connecting arteries to veins in the brain. AVMs form accidentally prior to birth. An AVM can form almost anywhere in the brain, brainstem, or spinal cord, but they are most common in the main cerebral hemispheres. An AVM near or on the outer surface of the brain can cause bleeding there (a subarachnoid haemorrhage); if deeper, it can cause bleeding inside the brain itself (intracerebral haemorrhage) – forms of haemorrhagic stroke. (See Stroke)

The haemorrhage may be large or small, and depending on the extent and location of the bleed, damage to brain tissues may be fatal or disabling, or relatively slight. AVMs occur in approximately 3 of every 10,000 people.

They appear rarely in several generations of the same family, and are more common in men. Bleeding from an AVM most often occurs between the ages of 10 and 30.

Symptoms

The most common symptoms of AVM (as those of haemorrhagic stroke) are:

• Sudden and severe headache, which may be localised or general, or resemble migraine headache in some cases
• Vomiting occurring with headache
• Vision changes, including decreased, double or blurred vision
• Seizures (fits)
• Muscle weakness in any part of the body
• Decreased sensation in any part of the body
• Sleepiness, lethargy, disorientation, irritability
• Stiff neck

A bleeding AVM is a medical emergency and requires immediate hospitalisation. If you or someone else is having these symptoms, call 000 (in Australia) immediately.

Treatment

The goal of treatment is to prevent further complications by limiting bleeding, controlling seizures and, if possible, removing the AVM.

The main types of treatment are;

• Open brain surgery,
• Endovascular treatment (a minimally invasive operation where a glue-like material is delivered into the diseased vessel, thus blocking it – this technique is called embolisation)
• Radiosurgery – focusing radiation on the diseased vessel.

Often, these treatments will be used in combination.

Outlook

AVMs that haemorrhage can lead to serious neurological problems and sometimes death. However, some people have AVMs that never cause problems. The expected outcome varies. Approximately 10% of cases which have haemorrhage as the first symptom are fatal. Seizures and neurologic changes may be permanent or may resolve with treatment.

Possible complications which may occur are:

• Intracerebral haemorrhage
• Subarachnoid haemorrhage
• Seizures
• Permanent neurologic changes such as paralysis or sensory problems
• Numbness of a part of the face or body
• Vision changes
• Language difficulties
• Persistent headache
• Hydrocephalus (A build-up of fluid in and around the brain and spinal cord)

Appropriate treatment will assist in full or partial recovery from most of these complications.

Recent Research Grants

2019 – Novel agents for the targeting of abnormal blood vessels in the brain to prevent stroke – Dr Lucinda McRobb – Read more >

2018 – Thrombotic nanodisks to block abnormal blood vessels in brain – Dr Zhenju Zhao – Read more >

2016 – Radiation-induced markers for vascular targeting of brain AVM tissues – Dr Zhenju Zhao – Read more >

Further information and support

Information

• Darren “Muddy” Laycock: The Impact of AVM | Read story
• Cerebral arteriovenous malformation (MedlinePlus) | Read article

Support

• National Stroke Foundation (with information on support services throughout Australia) | http://www.strokefoundation.org.au
• AVM Support Group Australia (Facebook) | https://www.facebook.com/groups/223195371615860/

Reviewed by Professor Nicholas Dorsch, Department of Neurosurgery, Westmead Hospital