Cerebral 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
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