Cerebral Arteriovenous Malformation

Arteriovenous malformation

Definition: Congenital abnormality consisting of a nidus of abnormal dilated tortuous arteries and veins with closely packed pathologic vessels. Results in shunting of blood from arterial to venous side without intermediary capillary bed.

Histopathology: Arteries have thin wall (no elastica, small amount muscularis); gliotic cerebral parenchyma between vessels.

Age: 80% by end 4th decade; 20%<20yrs.

Clinical: headache, seizure, mental deterioration; progressive hemispheric neurologic deficit (50%); ictus from acute intracranial haemorrhage (50%).

Classification: This lesion is Spetzler Grade 2: scoring 1 for size <3cm; 1 for position in eloquent cortex; 0 for superficial drainage.

Site: 90% supratentorial (commonest parietal); 10% infratentorial

Supply: pial branches ICA, dural branches ECA

Angiography: 1. dilated afferent and efferent vessels with a racemose tangle (bag of worms), 2. av shunt into at least 1 early draining vein, 3. negative angiogram may imply thrombosis or compression by haematoma.

Treatment: 1. conventional surgery, 2. endovascular embolization, 3. radiosurgery

Complications: 1. haemorrhage- bleed on venous side/ ruptured aneurysm. 2. infarct

Prognosis: 10% mortality; 30% morbidity; 2-3% yearly chance of bleeding (increases to 6% in year following 1st bleed, and to 25% in year following 2nd bleed).

References: 1) Dähnert W. Radiology Review Manual, 5th edition, Lippincott, Williams & Wilkins, 2003. 2) National Institutes of Health

Credit: Dr Marina-Portia Anthony