What is an AVM or fistula?
An arteriovenous malformation (AVM) is an abnormal connection between arteries and veins that can involve the brain or spine. AVMs usually occur prior to birth or early childhood, and slowly develop over time. AVMs occur in less than 1% of the population. There is no known cause.
What are symptoms of an AVM?
An AVM may not cause symptoms unless it ruptures, resulting in bleeding in the brain or spine. However, about half of patients with AVMs do have symptoms without rupture. Those symptoms may include
Symptoms when bleeding occurs are similar to those of a ruptured aneurysm or stroke
- Seizures
- Whooshing or buzzing noise in the ear (pulsatile tinnitus)
- Progressive weakness or numbness
- Blurry, double or decreased vision
- Headache or dizziness
Symptoms when bleeding occurs are similar to those of a ruptured aneurysm or stroke
- Sudden severe headache
- Weakness, numbness, unsteadiness or paralysis
- Difficulty with speech or understanding
- Vision loss
How is an AVM diagnosed?
- History and physical examination
- MRA or CTA
- Catheter angiography
How is an AVM treated?
Treatment options are determined by the size, location and type of AVM, as well as the medical history of the patient. There are several ways that AVMs are treated. Some treatments are used together.
Embolization – This procedure treats the AVM from inside the blood vessels and usually involves accessing the large artery in the groin via a small skin nick, and tracking a catheter, or small plastic tube, from the groin to the arteries of the AVM in the brain or spine. From there, glue or a glue-like substance is injected into the abnormal blood vessels to plug up the malformation, with the goal of reducing the chance of bleeding. This procedure can be performed independently, or in conjunction with surgery. It is performed by an interventional neuroradiologist.
Surgery – A neurosurgeon removes a section of the skull to gain access to the AVM. The tangle of abnormal blood vessels is then clipped off and carefully removed. The skull bone is then replaced, and the scalp is closed with stitches.
Stereotactic radiosurgery or Gamma Knife – Focused beams of radiation are used to destroy the AVM. The radiation causes the blood vessels to slowly regress, a process that occurs over months and often years following treatment. Despite the name, the procedure does not require open surgery.
Embolization – This procedure treats the AVM from inside the blood vessels and usually involves accessing the large artery in the groin via a small skin nick, and tracking a catheter, or small plastic tube, from the groin to the arteries of the AVM in the brain or spine. From there, glue or a glue-like substance is injected into the abnormal blood vessels to plug up the malformation, with the goal of reducing the chance of bleeding. This procedure can be performed independently, or in conjunction with surgery. It is performed by an interventional neuroradiologist.
Surgery – A neurosurgeon removes a section of the skull to gain access to the AVM. The tangle of abnormal blood vessels is then clipped off and carefully removed. The skull bone is then replaced, and the scalp is closed with stitches.
Stereotactic radiosurgery or Gamma Knife – Focused beams of radiation are used to destroy the AVM. The radiation causes the blood vessels to slowly regress, a process that occurs over months and often years following treatment. Despite the name, the procedure does not require open surgery.
