An arteriovenous malformation (AVM) is a congenital lesion which comprises an abnormal collection of blood vessels, where arterial blood flows directly into the draining veins without the normally intervening capillaries. AVMs appear as a "tangle" of blood vessels and most commonly occur in the brain or spinal cord.

Symptoms ​

Presenting symptoms include:

• Bleeding: 50% of patients with AVMs will present with a hemorrhage
• Seizures: 25% of patients have this as their presenting symptom
• Pressure on the surrounding brain resulting in stroke like symptoms
• Headaches
• The risk of hemorrhage from an AVM is estimated to be about 2 to 4 percent per year.

Diagnosis

Arteriovenous malformation can be diagnosed on a computed tomography (CT) or magnetic resonance imaging (MRI) scan.

They may be diagnosed incidentally or after hemorrhage.

After detection of an AVM, further evaluation needs to be carried out by cerebral angiography. This will give further information regarding the structure of the AVM, the contributing and drainage vessels which will influence treatment decisions.

AVMs are graded by the Spetzler-Martin grading system. This is based on points allocated based on the size, location and pattern of blood flow of the AVM.

The grading ranges from 1 to 5. The higher the grading, the greater the difficulty of treatment.

Treatment Options

• Conservative management and observation
• Endovascular embolisation combined with surgical excision
• Stereotactic radiosurgery

The factors involved in treatment include:

• Age of patient
• The current clinical condition of the patient
• Risks of surgery
• Morphology and location of the AVM